U.S. patent application number 09/879752 was filed with the patent office on 2002-03-07 for polymer matrix electroluminescent materials and devices.
Invention is credited to Marrocco, Matthew L. III, Motamedi, Farshad J..
Application Number | 20020028347 09/879752 |
Document ID | / |
Family ID | 22785611 |
Filed Date | 2002-03-07 |
United States Patent
Application |
20020028347 |
Kind Code |
A1 |
Marrocco, Matthew L. III ;
et al. |
March 7, 2002 |
Polymer matrix electroluminescent materials and devices
Abstract
Photoluminescent and electroluminescent compositions are
provided which comprise a matrix comprising aromatic repeat units
and a luminescent metal ion or luminescent metal ion complex.
Methods for producing such compositions, and the electroluminescent
devices formed therefrom, are disclosed.
Inventors: |
Marrocco, Matthew L. III;
(Rancho Cucamonga, CA) ; Motamedi, Farshad J.;
(San Dimas, CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
350 WEST COLORADO BOULEVARD
SUITE 500
PASADENA
CA
91105
US
|
Family ID: |
22785611 |
Appl. No.: |
09/879752 |
Filed: |
June 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60211108 |
Jun 12, 2000 |
|
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|
Current U.S.
Class: |
428/690 ;
252/301.16; 252/301.35; 252/301.36; 257/102; 257/103; 313/504;
313/506; 428/323; 428/917 |
Current CPC
Class: |
H01L 51/5016 20130101;
C08G 61/124 20130101; C09K 11/06 20130101; H05B 33/14 20130101;
H01L 51/5036 20130101; C08G 61/10 20130101; C08K 3/24 20130101;
C08L 79/04 20130101; H01L 51/0039 20130101; Y10T 428/25 20150115;
H01L 51/0004 20130101; H01L 51/0038 20130101; H01L 51/0089
20130101; H01L 51/5234 20130101; C08G 2261/1523 20130101; C09K
2211/145 20130101; H01L 51/5012 20130101; C08G 2261/12 20130101;
C09K 2211/1416 20130101; C09D 165/00 20130101; H01L 51/0035
20130101; C08G 61/125 20130101; C09K 2211/1466 20130101; H01L
51/5206 20130101; C09K 2211/1425 20130101; C08G 61/122 20130101;
C08G 2261/95 20130101; C09D 5/24 20130101; H01L 2251/306 20130101;
H01L 51/56 20130101; C09D 5/22 20130101; H01L 51/5072 20130101;
C08G 2261/312 20130101; C08G 73/22 20130101; H01L 51/0043 20130101;
C08G 61/126 20130101; C09D 165/02 20130101; C08G 2261/52 20130101;
C08G 61/12 20130101; C08L 65/00 20130101; C09K 2211/182 20130101;
C08G 73/18 20130101; H01L 51/5008 20130101; H01L 51/5056
20130101 |
Class at
Publication: |
428/690 ;
428/917; 428/323; 313/504; 313/506; 252/301.16; 252/301.35;
252/301.36; 257/102; 257/103 |
International
Class: |
H05B 033/14; C09K
011/06; C09K 011/08 |
Claims
What is claimed is:
1. A composition comprising a polymer comprising repeat units
selected from the group consisting of: 13where R is independently
selected from H, D, F, alkoxy, aryloxy, alkyl, aryl, alkyl ketone,
aryl ketone, alkylester, arylester, amide, carboxylic acid,
fluoroalkyl, fluoroaryl, polyalkalene oxy, any two of the R groups
may be bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, and q is
0-6, A and B are independently selected from the group consisting
of --O--, --S--, --NR.sub.1--, and --CR.sub.1R.sub.2--,
--CR.sub.1R.sub.2CR.sub.3R.sub.4--, --N.dbd.CR.sub.1--,
--CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and --(CO)-- where
R.sub.1-R.sub.4 are H, D, F, alkyl, aryl, alkyleneoxy,
polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and fluoroaryl, two
of the R groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is
0-5, q is 0-6, and r is 0-7, and E is selected from the group
consisting of O, NH, and S; and one or more luminescent metal ions
or luminescent metal ion complexes.
2. The composition of claim 1, wherein the luminescent metal ion or
luminescent metal ion complex comprises a lanthanide metal ion.
3. The composition of claim 1, wherein the polymer is a
copolymer.
4. The composition of claim 1, wherein the polymer is a dendritic
or hyperbranched polymer.
5. The composition of claim 1, wherein said polymer comprises
repeat units of structure II.
6. The composition of claim 1, wherein the luminescent metal ion or
luminescent metal ion complex comprises cerium.
7. The composition of claim 1, wherein the luminescent metal ion or
luminescent metal ion complex comprises europium.
8. The composition of claim 1, wherein the luminescent metal ion or
luminescent metal ion complex comprises terbium.
9. The composition of claim 1, wherein the polymer is a
copolymer.
10. The composition of claim 9, wherein one of the repeat units has
structure II.
11. The composition of claim 10, wherein for one of the repeat
units having structure II q is 0, A is --CR.sub.1R.sub.2--, and
R.sub.1 and R.sub.2 are alkyl.
12. The composition of claim 11, wherein a second repeat unit has
structure II, wherein q is 0, A is --CR.sub.1R.sub.2--, and R.sub.1
and R.sub.2 are independently selected from the group consisting of
H, D, F, alkyl, aryl, alkyleneoxy, polyalkyleneoxy, alkoxy,
aryloxy, fluoroalkyl, and fluoroaryl.
13. The composition of claim 1, wherein the luminescent metal ion
or luminescent metal ion complex is present as part of an inorganic
solid.
14. The composition of claim 13, wherein the inorganic solid is a
nanosized powder with physical dimensions in the 1 to 1000
nanometer range.
15. The composition of claim 14, wherein the inorganic solid is a
semiconductor.
16. The composition of claim 15, wherein the semiconductor is a
II-VI semiconductor.
17. The composition of claim 1, wherein the luminescent metal ion
or luminescent metal ion complex comprises a metal ion selected
from the group consisting of chromium, manganese, iron, cobalt,
molybdenum, ruthenium, rhodium, palladium, silver, tungsten,
rhenium, osmium, iridium, platinum, gold, and uranium.
18. An electroluminescent device comprising the composition of
claim 1.
19. The composition of claim 13, wherein the inorganic solid is a
semiconductor.
20. The composition of claim 19, wherein the semiconductor is a
II-VI semiconductor.
21. The composition of claim 1 having emission bands of 20 nm or
less.
22. The composition of claim 1 having emission bands of 10 nm or
less.
23. The composition of claim 1 having emission bands of 5 nm or
less.
24. The composition of claim 1 having emission bands of 3 nm or
less.
25. The composition of claim 1, wherein the luminescent metal ion
or luminescent metal ion complex comprises a polarizable
ligand.
26. The composition of claim 25, wherein the polarizable ligand is
selected from the group consisting of: 14
27. The composition of claim 25, wherein the polarizable ligand is
part of a polymer chain.
28. The composition of claim 27, wherein the polymer chain is a
conjugated polymer chain.
29. The composition of claim 1, wherein the polymer is a
crosslinked polymer.
30. The composition of claim 1, wherein the polymer is an
oligomer.
31. The composition of claim 1, wherein the polymer is a branched
polymer.
32. The composition of claim 1, wherein the polymer is a block
co-polymer.
33. The composition of claim 1, wherein the polymer is a random
co-polymer.
34. The composition of claim 1, wherein the polymer is a graft
co-polymer.
35. The composition of claim 1, wherein the conjugation length of
the polymer is controlled with non-aromatic spacer groups.
36. The composition of claim 35, wherein the spacer groups are
selected from the group consisting of --O--, --S--, --NR--,
--CR.sub.1R.sub.2--, (CH.sub.2).sub.n--, --(CF.sub.2).sub.n--,
ester, and amide.
37. The composition of claim 35, wherein the conjugation length is
between 2 and 50 conjugated rings.
38. The composition of claim 35, wherein the conjugation length is
between 3 and 10 conjugated rings.
39. The composition of claim 36, wherein the conjugation length is
between 3 and 6 conjugated rings.
40. An electroluminescent device comprising the composition of
claim 1.
41. The electroluminescent device of claim 40, wherein the polymer
is a crosslinked polymer.
42. An electroluminescent device comprising: a first electrode; one
or more charge transport materials; and an electroluminescent layer
comprising the composition of claim 1 and a second electrode.
43. The electroluminescent device of claim 42, wherein one or both
of said electrodes is a transparent electrode.
44. The electroluminescent device of claim 42, wherein one or both
of said electrodes comprises tin oxide or doped tin oxide.
45. The electroluminescent device of claim 42, wherein one of the
charge transport materials is a hole transport material provided as
a distinct layer.
46. The electroluminescent device of claim 42 comprising two
layers; a first layer comprising a hole transport material, and the
electroluminescent layer which comprises an electron transport
material.
47. The electroluminescent device of claim 42, wherein an electron
transport material is provided as a distinct layer.
48. The electroluminescent device of claim 42 comprising two
layers; a first layer comprising an electron transport material,
and the electroluminescent layer which comprises a hole transport
material.
49. The electroluminescent device of claim 42 comprising three
layers, the electroluminescent layer sandwiched between a layer of
electron transport material and a layer hole transport
material.
50. The electroluminescent device of claim 49, wherein the layers
are not distinct, but graded.
51. The electroluminescent device of claim 42 comprising a hole
transport material and an electron transport material both of which
are graded in the electroluminescent layer.
52. The electroluminescent device of claim 42, wherein the emission
bands are 20 nm or less.
53. The electroluminescent device of claim 42, wherein the emission
bands are 10 nm or less.
54. The electroluminescent device of claim 42, wherein the emission
bands are 5 nm or less.
55. The electroluminescent device of claim 42, wherein the emission
bands are 3 nm or less.
56. The electroluminescent device of claim 42, wherein the
electroluminescent layer comprises a nanosized powder with physical
dimensions in the 1 to 1000 nanometer range.
57. The electroluminescent device of claim 42, wherein the turn-on
voltage is less than 15V.
58. The electroluminescent device of claim 42, wherein the turn-on
voltage is less than 10V.
59. The electroluminescent device of claim 42, wherein the turn-on
voltage is less than 5V.
60. An electroluminescent composition comprising: an aromatic
hydrocarbon matrix; and a lanthanide metal complex having an
aromatic ligand.
61. The composition of claim 60, wherein said aromatic ligand has a
diaryl group.
62. The composition of claim 60, wherein said aromatic ligand has a
two ring fused ring group.
63. The composition of claim 60, wherein said aromatic ligand has a
triaryl group.
64. The composition of claim 60, wherein said aromatic ligand has a
three ring fused ring group.
65. The composition of claim 60, wherein said aromatic ligand has a
polyaryl group.
66. An electroluminescent device comprising the composition of
claim 60.
67. An electroluminescent device comprising: a first electrode; one
or more charge transport layers; and an electroluminescent layer
comprising the compoition of claim 60 and a second electrode.
68. The electroluminescent device of claim 67, wherein one or both
of said electrodes is a transparent electrode.
69. The electroluminescent device of claim 67, wherein one or both
of said electrodes comprises tin oxide or doped tin oxide.
70. The electroluminescent device of claim 67, wherein one of the
layers is a hole transport layer.
71. The electroluminescent device of claim 67, wherein one of the
layers is a hole transport layer and another of the layers is a
mixed layer comprising a luminescent material and an electron
transport material.
72. The electroluminescent device of claim 67, wherein one of the
layers is an electron transport layer.
73. The electroluminescent device of claim 67, wherein one of the
layers is an electron transport layer and another of the layers is
a mixed layer comprising a luminescent material and a hole
transport material.
74. The electroluminescent device of claim 67, wherein one of the
layers is a hole transport layer, another of the layers is a
luminescent layer, and another of the layers is an electron
transport layer.
75. The electroluminescent device of claim 73, wherein the mixed
layer is graded.
76. A composition comprising a polarizable matrix comprising
discrete molecules and a luminescent lanthanide metal ion.
77. The composition of claim 76, wherein the polarizable matrix is
a long arm spiro compound.
78. The composition of claim 76, wherein the polarizable matrix is:
15
79. A composition comprising a polymer comprising the repeat unit:
16where R is independently selected from H, D, F, Cl, Br, I alkoxy,
aryloxy, alkyl, aryl, alkyl ketone, aryl ketone, alkylester,
arylester, amide, carboxylic acid, fluoroalkyl, fluoroaryl,
polyalkalene oxy, any two of the R groups may be bridging, m is
0-2, n is 0-3, o is 0-4, p is 0-5, and q is 0-6, A and B are
independently selected from the group consisting of --O--, --S--,
--NR.sub.1--, and --CR.sub.1R.sub.2--,
--CR.sub.1R.sub.2CR.sub.3R.sub.4--, --N.dbd.CR.sub.1--,
--CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and --(CO)-- where
R.sub.1-R.sub.4 are H, D, F, alkyl, aryl, alkyleneoxy,
polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and fluoroaryl, two
of the R groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is
0-5, q is 0-6, and r is 0-7, and E is selected from the group
consisting of 0, NH, and S, and one or more luminescent metal ions
or luminescent metal ion complexes, wherein said polymer has a
molecular weight of greater than about 30,000 Daltons.
80. The composition of claim 79, wherein said polymer has a
molecular weight greater than about 50,000 Daltons.
81. The composition of claim 79, wherein said polymer has a
molecular weight greater than about 60,000 Daltons.
82. The composition of claim 79, wherein said polymer has a
molecular weight greater than about 100,000 Daltons.
83. The composition of claim 79, wherein said polymer has a
molecular weight greater than about 150,000 Daltons.
84. The composition of claim 79, wherein said polymer has a
molecular weight greater than about 200,000 Daltons.
85. The composition of claim 79, wherein said polymer has an
inherent viscosity of at least 1.8 dL/g.
86. The composition of claim 79, wherein said polymer has an
inherent viscosity of at least 4.2 dL/g.
87. The composition of claim 79, wherein o is 1, and R is selected
from the group consisting of --(C.dbd.O)NR.sub.1R.sub.2, --benzoyl,
--NR.sub.1R.sub.2, --OR.sub.1, --CHR.sub.1R.sub.2, -phenyl,
-naphthyl, and -2-benzoxazole, and R.sub.1 and R.sub.2 are as
defined above.
88. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal in complex comprises a lanthanide metal
ion.
89. The composition of claim 79, wherein the polymer is a
copolymer.
90. The composition of claim 79, wherein the polymer is a dendritic
or hyperbranched polymer.
91. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex comprises cerium.
92. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex comprises europium.
93. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex comprises terbium.
94. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex is present as part of an inorganic
solid.
95. The composition of claim 94, wherein the inorganic solid is a
nanosized powder with physical dimensions in the 1 to 1000
nanometer range.
96. The composition of claim 94, wherein the inorganic solid is a
semiconductor.
97. The composition of claim 96, wherein the semiconductor is a
II-VI semiconductor.
98. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex comprises a metal ion selected
from the group consisting of chromium, manganese, iron, cobalt,
molybdenum, ruthenium, rhodium, palladium, silver, tungsten,
rhenium, osmium, iridium, platinum, gold, and uranium.
99. An electroluminescent device comprising the composition of
claim 79.
100. The composition of claim 95, wherein the inorganic solid is a
semiconductor.
101. The composition of claim 95, wherein the semiconductor is a
II-VI semiconductor.
102. The composition of claim 101 having emission bands of 20 nm or
less.
103. The composition of claim 101 having emission bands of 10 nm or
less.
104. The composition of claim 79 having emission bands of 5 nm or
less.
105. The composition of claim 79 having emission bands of 3 nm or
less.
106. The composition of claim 79, wherein the luminescent metal ion
or luminescent metal ion complex comprises a polarizable
ligand.
107. The composition of claim 106, wherein the polarizable ligand
is selected from the group consisting of: 17
108. The composition of claim 106, wherein the polarizable ligand
is part of a polymer chain.
109. The composition of claim 118, wherein the polymer chain is a
conjugated polymer chain.
110. The composition of claim 79, wherein the polymer is a
crosslinked polymer.
111. The composition of claim 79, wherein the polymer is an
oligomer.
112. The composition of claim 79, wherein the polymer is a branched
polymer.
113. The composition of claim 79, wherein the polymer is a block
co-polymer.
114. The composition of claim 79, wherein the polymer is a random
co-polymer.
115. The composition of claim 79, wherein the polymer is a graft
co-polymer.
116. The composition of claim 79, wherein the conjugation length of
the polymer is controlled with non-aromatic spacer groups.
117. The composition of claim 116, wherein the spacer groups are
selected from the group consisting of --O--, --S--, --NR--,
--CR.sub.1R.sub.2--, (CH.sub.2).sub.n--, --(CF.sub.2).sub.n--,
ester, and amide.
118. The composition of claim 116, wherein the conjugation length
is between 2 and 50 conjugated rings.
119. The composition of claim 116, wherein the conjugation length
is between 3 and 10 conjugated rings.
120. The composition of claim 116, wherein the conjugation length
is between 3 and 6 conjugated rings.
121. An electroluminescent device comprising: a first electrode;
one or more charge transport layers; and an electroluminescent
layer comprising the composition of claim 79 and a second
electrode.
122. The electroluminescent device of claim 121, wherein one or
both of said electrodes is a transparent electrode.
123. The device of claim 121, wherein one or both of said
electrodes comprises tin oxide or doped tin oxide.
124. The device of claim 121, wherein one of the charge transport
material is a hole transport material provided as a distinct
layer.
125. The device of claim 121 comprising two layers; a first layer
comprising a hole transport material and the electroluminescent
layer.
126. The device of claim 121, wherein an electron transport
material is provided as a layer.
127. The device of claim 121 comprising two layers; a first layer
comprising an electron transport material and the
electroluminescent layer additionally comprising a hole transport
material.
128. The device of claim 121 comprising three layers; the
electroluminescent layer sandwiched between a layer of electron
transport material and a layer hole transport material.
129. The device of claim 128, wherein the layers are not distinct,
but are graded.
130. The electroluminescent device of claim 121 comprising a hole
transport material and an electron transport material both of which
are graded in the electroluminescent layer.
131. The electroluminescent device of claim 121, wherein the
emission bands are 20 nm or less.
132. The electroluminescent device of claim 121, wherein the
emission bands are 10 nm or less.
133. The electroluminescent device of claim 121, wherein the
emission bands are 5 nm or less.
134. The electroluminescent device of claim 121, wherein the
emission bands are 3 nm or less.
135. The electroluminescent device of claim 121, wherein the
electroluminescent layer comprises a nanosized powder with physical
dimensions in the 1 to 1000 nanometer range.
136. The electroluminescent device of claim 121, wherein the
turn-on voltage is less than 15V.
137. The electroluminescent device of claim 121, wherein the
turn-on voltage is less than 10V.
138. The electroluminescent device of claim 121, wherein the
turn-on voltage is less than 5V.
139. A composition comprising a polymer of the structure:
R--polarizable ligand --R.paren close-st.Y.paren close-st.; and one
or more luminescent metal ions or metal ion complexes, wherein R is
independently selected from H, D, F, Cl, Br, I, alkoxy, aryloxy,
alkyl, aryl, alkyl ketone, aryl ketone, alkylester, arylester,
amide, carboxylic acid, fluoroalkyl, fluoroaryl, polyalkalene oxy,
any two of the R groups may be bridging, and Y is a polymer repeat
unit.
140. The composition of claim 139, wherein the luminescent metal
ion or luminescent metal ion complex comprises a metal ion selected
from the group consisting of chromium, manganese, iron, cobalt,
molybdenum, ruthenium, rhodium, palladium, silver, tungsten,
rhenium, osmium, iridium, platinum, gold and uranium.
141. The composition of claim 139, wherein the polarizable ligand
is selected for the group consisting of: 18
142. The composition of claim 139, wherein Y is selected from the
group consisting of: 19where R on the Y repeat unit(s) is
independently selected from H, D, F, Cl, Br, I, alkoxy, aryloxy,
alkyl, aryl, alkyl ketone, aryl ketone, alkylester, arylester,
amide, carboxylic acid, fluoroalkyl, fluoroaryl, polyalkalene oxy,
any two of the Y repeat unit R groups may be bridging, m is 0-2, n
is 0-3, o is 0-4, p is 0-5, and q is 0-6, A and B are independently
selected from the group consisting of --O--, --S--, --NR.sub.1--,
and --CR.sub.1R.sub.2--, --CR.sub.1R.sub.2CR.sub.3R.sub.4--,
--N.dbd.CR.sub.1--, --CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and
--(CO)-- where R.sub.1-R.sub.4 are H, D, F, Cl, Br, I, alkoxy,
aryloxy, alkyl, aryl, alkyleneoxy, polyalkyleneoxy, alkoxy,
aryloxy, fluoroalkyl, and fluoroaryl, two of the R groups may be
bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, q is 0-6, and r
is 0-7, and E is selected from the group consisting of O, NH, and
S.
143. A composition comprising a polymer comprising repeat units
selected from the group consisting of: 20where R is independently
selected from H, D, F, Cl, Br, I, alkoxy, aryloxy, alkyl, aryl,
alkyl ketone, aryl ketone, alkylester, arylester, amide, carboxylic
acid, fluoroalkyl, fluoroaryl, polyalkalene oxy, any two of the R
groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, and
q is 0-6, A and B are independently selected from the group
consisting of --O--, --S--, --NR.sub.1--, and --CR.sub.1R.sub.2--,
--CR.sub.1R.sub.2CR.sub.3R.sub.4--- , --N.dbd.CR.sub.1--,
--CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and --(CO)-- where
R.sub.1-R.sub.4 are H, D, F, alkyl, aryl, alkyleneoxy,
polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and fluoroaryl, two
of the R groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is
0-5, q is 0-6, and r is 0-7, and E is selected from the group
consisting of O, NH, and S; and one or more luminescent metal ions
or luminescent metal ion complexes.
144. The composition of claim 143, wherein said polymer has a
molecular weight greater than about 50,000 Daltons.
145. The composition of claim 143, wherein said polymer has a
molecular weight greater than about 60,000 Daltons.
146. The composition of claim 143, wherein said polymer has a
molecular weight greater than about 100,000 Daltons.
147. The composition of claim 143, wherein said polymer has a
molecular weight greater than about 150,000 Daltons.
148. The composition of claim 143, wherein said polymer has a
molecular weight greater than about 200,000 Daltons.
149. The composition of claim 143, wherein said polymer has an
inherent viscosity of at least 1.8 dL/g.
150. The composition of claim 143, wherein said polymer has an
inherent viscosity of at least 4.2 dL/g.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a related to provisional patent
application No. 60/211,108, filed Jun. 12, 2000, entitled POLYMER
MATRIX ELECTROLUMINESCENT MATERIALS AND DEVICES, the entire
disclosure of which is expressly incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to photoluminescent and
electroluminescent compositions comprising a matrix comprising
aromatic repeat units and a luminescent metal ion or a luminescent
metal ion complex. The invention also relates to method for making
such compositions and electroluminescent devices using such
compositions.
BACKGROUND OF THE INVENTION
[0003] Many types of luminescent devices exist, including a number
of all solid state devices. Solid state devices are preferable over
incandescent or fluorescent bulbs in that they are lighter; more
compact, can be made smaller, and can have higher efficiency.
Examples of solid state luminescent devices are light emitting
diodes (LEDs), such as gallium arsenide or silicon carbide LEDs,
organic light emitting diodes (OLEDs), such as OLED displays being
marketed by Uniax Corporation and CDT Ltd., and doped zinc sulfide
devices that have been marketed for a number of years, for example
by GE(t as Limelite.TM. nightlights, and American Tack and
Hardware, Co. Inc., (Monsey, N.Y.) as Nitelite.TM. nightlights. Any
of these devices can be fabricated into arrays to represent numbers
or letters, or pictures.
[0004] Of the various luminescent devices and displays the OLEDs
are the newest and least mature technology. OLEDs typically consist
of a thin film structure comprising a transparent electrode,
usually indium doped tin oxide (ITO) on a glass or plastic support
layer, the ITO optionally coated with polyaniline or
poly(ethylenedioxythiophene) (PEDOT), one or more organic
containing layers, typically a hole conducting layer, for example,
of a triphenylamine derivative, a luminescent layer, for example, a
polyphenylenevinylene derivative or a polyfluorene derivative, an
electron conducting layer, for example, an oxadiazole derivative,
and a second electrode, for example, calcium, magnesium, aluminum,
and the like.
[0005] The advantages of the OLED devices are, lightweight,
potentially low cost (although this has yet to be demonstrated
commercially), the ability to fabricate thin film, flexible
structures, wide viewing angle, and high brightness. The
disadvantages of OLEDs are short device lifetimes, increasing
voltages when operated in a constant current mode, and broad
spectral widths. The efficiency of OLEDs is limited by the nature
of the excited state of organic molecules. Typically, both the
singlet and triplet excited states are populated during the
operation of an OLED. Unfortunately, only decay from the singlet
state produces useful light. Decay from the triplet state to a
singlet ground state is spin forbidden and therefore slow, giving
non-radiative processes more time to take place. Because the
triplet state is three-fold degenerate and the singlet state is not
degenerate; three quarters of the excited electrons enter the
triplet state and produce little or no light.
[0006] An additional disadvantage of OLEDs is the relatively short
lifetime of the excited state of organic molecules. In a display
application each pixel is scanned 10 to 100 times every second,
typically 60 times every second. It is desirable for the light from
the pixel to decay on about the same time scale. If the pixel
decays too slowly each subsequent image will be scanned over the
not yet faded previous image, and the image will blur. If the pixel
decays too quickly, there will be a noticeable flicker.
[0007] There is a need for a solid state device that is not limited
by the short lifetimes of OLEDs. The short life of OLEDs is
suspected to arise from the decomposition or alteration of the
organic layers during operation.
[0008] There is also a need for electroluminescent devices that
have stable I-V characteristics making the associated electronics
simpler.
[0009] There is also a need for electroluminescent devices with
pure color characteristics that are more amenable to color
displays. For color television, monitors, and the like, red, blue,
and green devices with exacting color are required.
[0010] There is also a need for electroluminescent devices with
higher efficiency, not limited by decay from non-luminescent
triplet states.
[0011] There is also a need for electroluminescent devices with
phosphorescent decay times in the appropriate range for scanned
displays and passive displays.
SUMMARY OF THE INVENTION
[0012] In one aspect, the present invention is directed to a
polymer composition comprising repeat units selected from the group
consisting of: 1
[0013] where R is independently selected from H, D, F, Cl, Br, I,
alkoxy, aryloxy, alkyl, aryl, alkyl ketone, aryl ketone,
alkylester, arylester, amide, carboxylic acid, fluoroalkyl,
fluoroaryl, polyalkalene oxy, any two of the R groups may be
bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, q is 0-6, r is
0-7, A and B are independently selected from the group consisting
of --O--, --S--, --NR.sub.1--, and --CR.sub.1R.sub.2--,
--CR.sub.1R.sub.2CR.sub.3R.sub.4--, --N.dbd.CR.sub.1--,
--CR.sub.1.dbd.CR.sub.2-, --N.dbd.N--, and --(CO)-- where
R.sub.1-R.sub.4 are H, D, F, Cl, Br, I, alkyl, aryl, alkyleneoxy,
polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and fluoroaryl, two
of the R groups may be bridging, and E is selected from the group
consisting of O, NH, and S, and one or more fluorescent metal
ions.
[0014] In another aspect, the invention is directed to an
electroluminescent device comprising the composition set forth
above. In one embodiment, the electroluminescent device comprises a
first electrode, one or more charge transport layers, an
electroluminescent layer comprising the composition set forth above
and a second electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These and other features, aspects, and advantages of the
present invention will be more fully understood when considered
with respect to the following detailed description, appended
claims, and accompanying drawings, wherein:
[0016] FIG. 1 is a semi-schematic side view of one embodiment of an
electroluminescent device provided in accordance with practice of
the present invention;
[0017] FIG. 2 is a semi-schematic exploded view of the
electroluminescent device of FIG. 1;
[0018] FIG. 3 shows an array of electroluminescent devices
extending in two dimensions provided in accordance with practice of
the present invention;
[0019] FIG. 4 is a semi-schematic side view of another embodiment
of an electroluminescent device provided in accordance with
practice of the present invention which comprises an electron
transfer layer but no hole transfer layer; and
[0020] FIG. 5 is a semi-schematic side view of an
electroluminescent device provided in accordance with practice of
the present invention having a graded electroluminescent layer.
DETAILED DESCRIPTION
[0021] In order to overcome the deficiencies of previous
luminescent devices it would be desirable to have a device with
higher efficiency than current OLEDs, and with longer lifetimes. It
would also be desirable to have a device that operated at low
voltage, preferably less than 20 volts, more preferably less than
15 volts, even more preferably less than 10 volts, and most
preferably less than 5 volts DC. It would also be desirable to have
a device with good color quality, and appropriate phosphorescent
decay time for displays.
[0022] We have found that many of the disadvantages of OLEDs may be
overcome by use of a combination of a fluorescent metal ion and an
organic matrix designed to collect and deposit energy into the
fluorescent metal ion, as the luminescent layer(s) in an
electroluminescent device. The matrix typically comprises a
polymer, but may be an oligomer, or discrete molecules. The matrix
will accept electrons and/or holes from the electrodes and
transport them toward the center of the device where they recombine
to produce an excited electronic state in the matrix. Materials
that fluoresce well tend to also electroluminesce well, and are
thus good candidates for the matrix of the present invention. The
band gap of the matrix (or in other terms the HOMO-LUMO difference)
will determine the energy of the excited state, and how much energy
is available to excite the luminescent metal. A polymer matrix that
luminesces in the red will generally not be able to transfer energy
to a metal that luminesces blue, except in the unusual case of a
two photon or higher order process. Thus it is desirable to choose
a polymer matrix that luminesces blue, indigo, violet, or
ultraviolet, i.e., the high energy part of the spectrum, so that
transfer to metals that luminesce blue, green, or red is
possible.
[0023] The fluorescent spectrum of organic polymers, oligomers, and
discrete organic molecules are typically very broad, often 50 or
100 nm wide. The absorption and emission bands of lanthanide metals
are very narrow, typically 5 to 20 nm, because the bands result
from transitions between f orbitals which are "buried" within outer
filled d and s orbitals. Since they are screened by the outer d and
s orbitals they are less effected by external electric fields and
transitions within the f manifold are not broadened. The narrow
bands provide very pure colors, a desirable feature for display
fluorophors.
[0024] Lanthanide metals have been used as cathodoluminescent
materials for many years in color television picture tubes,
commonly called cathode ray tubes (CRTs). It is well known that
certain lanthanide metals have fluorescent bands very near the
ideal color coordinates for red, blue and green, in CRTs. By using
a polymer matrix (with its broad spectrum) to excite a lanthanide
metal (with its narrow spectrum, and good color coordinates) a much
better color rendition is achieved. The lanthanides are yttrium,
lanthanum, cerium, praseodymium, neodymium, promethium, samarium,
europium, gadolinium, terbium, dysprosium, holmium, erbium,
thulium, ytterbium, and lutetium.
[0025] Lanthanide metals, and other luminescent metals, have
excited state lifetimes that are closer to the lifetime needed for
displays than are the lifetimes of organic materials.
[0026] The excited state of a lanthanide ion produces much more
light (about four times more) than an excited organic compound.
Also, the luminescent metal ion or complexes can accept energy from
both singlet and triplet states of organic molecules. In this way,
the excited energy in the organic singlet state that was otherwise
destined to be lost to non-radiative transitions is transferred to
a metal, which then radiates.
[0027] Metal ions are much less subject to bleaching or chemical
reactions that destroy the fluorophor than organic species. The
term fluorophor is used here to mean the chemical system that
absorbs energy and re-emits it, typically the emitted energy is
light of lower energy than the absorbed energy. The chemical system
may be an atom, an ion, a molecule, a metal complex, an oligomer, a
polymer, or two or more atoms, ions, or molecules in close
proximity, capable of exchanging energy. Fluorophors may be, but
are not limited to being, photoluminescent, fluorescent,
phosphorescent, cathodoluminescent, or electroluminescent. Although
the devices of the instant invention are still partly organic, the
metal ions exert a protective effect by removing energy from the
organic excited state. The devices of the present invention are
thus expected to have longer lifetimes than all organic
devices.
[0028] In the practice of the present invention, a luminescent or
fluorescent metal ion or complex, preferably a lanthanide metal ion
or complex, is embedded within a fluorescent organic matrix,
producing a system wherein the organic matrix may be elevated to an
excited state, which then transfers its energy to the metal ion or
complex which then emits light. The energy transfer between organic
matrix and metal may be enhanced by providing coordination sites
for the metal on the organic matrix. The energy transfer may also
be enhanced by providing the metal with polarizable ligands.
[0029] The luminescent metal ion may be any metal ion or metal
complex that luminesces, including, but not limited to, transition
metal ions such as manganese, silver, ruthenium, iridium, and
platinum, lanthanide ions, and complexes thereof. Lanthanide ions
are preferred because of their narrow spectral line widths.
[0030] The electroluminescent (EL) compositions and EL devices of
the present invention will have very narrow emission lines because
the emission is primarily from a lanthanide metal ion. As noted
above, lanthanide metal ions have narrow emission bands, typically
5 to 20 nm in width (full width at half maximum, FWHM). The FWHM of
the electroluminescent compositions and devices of the present
invention will be less than about 50 nm, preferably less than about
20 nm, more preferably less than about 10 m, even more preferably
less than about 8 nm, yet more preferably less than about 5 nm,
even yet more preferably less than about 4 nm, and most preferably
less than 3 nm.
[0031] The luminescent metal ion may be coordinated or complexed to
a ligand, or may be complexed or coordinated to a polymer. One or
more counter ions may also be present, and these may or may not
coordinate to the metal. The luminescent metal ions may form
clusters or may be part of a cluster of metals. Ligands and counter
ions may also coordinate two or more luminescent metals, in a
bridging fashion.
[0032] The luminescent metal ions may be present as part of an
inorganic solid. For example, an inorganic powder, comprising a
luminescent metal ion may be mixed with a luminescent polymer. The
inorganic powder is preferably 400 mesh (average particle size less
than about 38 microns), or finer, more preferably less than about
20 microns, even more preferably less than about 5 microns, and
most preferably less than about 3 microns. The inorganic powder may
be a nanosized powder with average physical dimensions in the 1 to
1000 nanometer range, preferably less than about 500 nanometers,
and more preferably less than about 100 nanometers. Nanometer sized
particles have very high surface to volume ratios and a high
fraction of the metal ions are at the surface of the particle or
within several angstroms (several tens of nanometers) of the
surface, making energy transfer from a polymer in which the powder
is embedded possible. Nanosized particles less than about 300 nm do
not scatter visible light. In the practice of the present
invention, the light emitting films may be less than 1000 nm and,
if particles are to be used, the particles must be smaller than the
film thickness. The inorganic solid may be a semiconductor.
Non-limiting examples of semiconductors are gallium nitride, tin
oxide, zinc oxide, zinc sulfide, cadmium sulfide, cadmium selenide,
lead oxide, and the like. Semiconductors comprising elements of
groups II and VI (II-VI semiconductors) can often be prepared by
wet chemical methods and are therefore preferred.
[0033] Merely mixing a fluorescent polymer with a fluorescent metal
ion or complex does not guarantee that energy can be transferred
from the polymer to the metal. The excited state of the polymer
must be at a higher energy level than the excited state of the
metal, otherwise little or no energy will be transferred.
Additionally, we have found that the probability of energy transfer
can be increased by providing a polymer having functional groups,
either side groups, or main chain groups, or end groups, that bind
or coordinate to the luminescent metal ion, or metal complex. Any
functional group that coordinates to a metal may be used. It will
be understood by one skilled in the art how to determine if a
functional group is coordinated, for example, by observation of
spectral shifts of the functional group in the IR, visible, or NMR
spectra. Functional groups may be monodentate, or chelating
multidentate, or macrocyclic. Functional groups that may be used
include but are not limited to amines, amides, alcohols, alpha
diketones, alpha ketoalcohols, beta diketones, beta ketoalcohols,
beta ketoacids, bipyridines, biquinolines, borates, carboxylic
acids, catecols, diols, hydroxyquinolines, phenanthrolenes,
phenols, phosphates, polyamines, polyethers, pyridines, quinolines,
salicylates, sulfates, thioethers, thiols, thiophenes, and the
like. Functional groups may lose one or more protons upon
coordination to the luminescent metal ion.
[0034] The functional groups on the polymer may replace all or some
of the ligands on the fluorescent metal. That is, the metal may
have additional ligands other than the polymer functional groups,
including coordinated solvent, and coordinated counter ions. We
have also found that the luminescent metal ion complex may be
chosen to enhance energy transfer from polymer to metal. Even if
the metal is not bound directly to the polymer by a covalent or
coordinate bond, energy transfer may be enhanced by choosing a
ligand that interacts with the polymer, e.g., by van der Waals,
hydrogen bonds, dipole-dipole, dipole-induced dipole, or other
non-covalent interaction. Energy transfer may be enhanced by use of
a ligand bearing polarizable groups, for example, aromatic groups
and especially multiple or fused ring aromatic groups such as
biphenyl, triphenyl, quaterphenyl, naphthyl, anthracenyl,
phenanthrenyl, pyridyl, quinolinyl, phenanthrolinyl, benzoxazolyl,
and the like. A polarizable ligand in general has electrons that
can respond to an electric or electromagnetic field. For the
purposes of the present invention, a polarizable ligand will have
at least one double bond; preferably, a carbon-carbon double bond.
More preferably, the polarizable ligand will have two or more
double bonds; even more preferably, three or more double bonds; yet
more preferably, four or more double bonds; even yet more
preferably, five or more double bonds; and most preferably, six or
more double bonds. It is further preferable that some or all of the
double bonds be conjugated with one another. The double bonds may
be part of an aromatic or heteroaromatic ring, such as a benzene,
pyridine, or quinoline ring. The aromatic ring may be terminal
(eg., phenyl) or internal (e.g., phenylene). For the purposes of
the present invention, conjugated ligands are polarizable
ligands.
[0035] Non-limiting examples of polarizable ligands include
benzoylacetone, dibenzoylmethane, benzoin, phenanthrolene,
phenylphenanthrolene, bipyridine, phenylbipyridine,
diphenylbipyridine, Ar(CO)(CHOH)Ar', Ar(CO)CH.sub.2(CO)Ar',
salicylic acid, salicylaldehyde, phenylsalicylic acid,
phenylsalicylaldehyde, adenine, purine, 2-aminobenzophenone,
2-amino-4-chlorobenzophenone, 2-(2-hydroxyphenyl)benzothiazole,
2-(2-hydroxyphenyl)quinoline, 1-naphthol-2-carboxaldehyde,
1,2-dihydroxybenzene, 1,2-dihydroxynaphthalene,
2,3-dihydroxynaphthylene, 1,8-dihydroxynaphthylene,
1-hydroxybenzophenone, 1-hydroxyfluorenone, 7-hydroxyinden-1-one,
7-hydroxy-3-phenylinden-1-one, salen, 8-hydroxyquinoline,
8-hydroxyquinazoline, 8-hydroxyquinoxaline, 4-hydroxybenzoxazole,
7-hydroxybenzoxazole, 4-hydroxy-2-phenyl benzoxazole,
7-hydroxy-2-phenylbenzoxazole, hypoxanthine, and the like. Aryl, Ar
and Ar' are independently selected from the group consisting of
phenyl, 2-biphenyl, 3-biphenyl, 4-biphenyl, 1-naphthyl, 2-naphthyl,
2-pyridyl, 3-pyridyl, 4-pyridyl, terphenyl (any isomer),
quaterphenyl (any isomer), anthracenyl, phenanthrenyl, pyridyl,
quinolinyl, phenanthrolinyl, benzoxazolyl, and quinazolinyl,
optionally substituted with D (deuterium), F, Cl, Br, I alkyl,
alkoxy, polyalkaleneoxy and fluoroalkyl. Preferably a ligand will
have at least one aromatic ring, more preferably a ligand will have
at least two aromatic rings, even more preferably a ligand will
have at least three aromatic rings. Preferably a ligand will have a
direct bond between two of the aryl groups such that they form a
biaryl group, or will have two rings in a fused ring system.
Biaryls and fused rings have higher polarizability than single ring
systems and therefore will couple better to the polymer excited
state. It is also preferable for the ligand to have a triaryl group
or fused three-ring group.
[0036] Non-limiting examples of general structural formulae of
polarizable ligands are shown below. 2
[0037] where R is independently selected from H, D, F, Cl, Br, I,
alkoxy, aryloxy, alkyl, aryl, alkyl ketone, aryl ketone,
alkylester, arylester, amide, carboxylic acid, fluoroalkyl,
fluoroaryl, polyalkalene oxy (e.g. methoxyethoxyethoxy,
ethoxyethoxy, and --(OCH.sub.2CH.sub.2).sub.xOH x.dbd.1-100), two
of the R groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is
0-5, q is 0-6, r is 0-7, and s is 0-8. The R groups may be on any
ring in a multiple ring structure. For example, in structure 12
there may be R groups on the heterocyclic ring, on the phenolic
ring, or on both. An example of bridging R groups is given in
structure 20 below. Structure 20 is derived from structure 8 where
two of the R groups taken together are --CH.dbd.CH--CH.dbd.CH--.
3
[0038] Additional examples of polarizable ligands include
R--C.sub.6H.sub.4--CO.sub.2H, R--C.sub.6H.sub.4--SO.sub.3H,
R--C.sub.6H.sub.4--PO.sub.3H.sub.2, substituted nicotinic acids
R--C.sub.5H.sub.3N--CO.sub.2H, substituted salicylic acids, and the
like.
[0039] It will be apparent to one skilled in the art that the
polarizable ligands could be used as functional groups if they are
covalently attached to a polymer chain. For example, any of the R
groups in the structures could represent a polymer chain. A
polarizable ligand may also form part of the backbone of a polymer
chain, for example, being attached through R groups (in the cases
where R has a hydrogen that may be replaced by a polymer chain,
e.g. aryl, alkyl, but not e.g. F, Br).
[0040] The general formula for a polarizable ligand as part of the
backbone of a polymer chain is: R--polarizable ligand--R.paren
close-st.Y.paren close-st. wherein Y is a generalized repeat
unit.
[0041] A specific example of the foregoing is: 4
[0042] In structure 21 Y is a generalized repeat unit, and could
be, for example, any of the repeat units I-XII below. 5
[0043] where R is independently selected from H, D, F, Cl, Br, I,
alkoxy, aryloxy, alkyl, aryl, alkyl ketone, aryl ketone,
alkylester, arylester, amide, carboxylic acid, fluoroalkyl,
fluoroaryl, polyalkalene oxy, any two of the R groups may be
bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, q is 0-6, r is
0-7, and A and B are independently selected from the group
consisting of --O--, --S--, --NR.sub.1--, --PR.sub.1-- and
--CR.sub.1R.sub.2--, --CR.sub.1R.sub.2CR.sub.3R.sub.4,
--N.dbd.CR.sub.1--, --CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and
--(CO)-- where R.sub.1-R.sub.4 are H, D, F, Cl, Br, I, alkyl, aryl,
alkyleneoxy, polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and
fluoroaryl, two of the R groups may be bridging, and E is selected
from the group consisting of O, NH, and S.
[0044] The polymers of the present invention are typically aromatic
polymers, having relatively short conjugation lengths leading to
fluorescence in the blue to ultraviolet region. Preferably the
conjugation length will be 2 to 50 conjugated rings, more
preferably 3 to 10 conjugated rings, even more preferably 3 to 6
conjugated rings. Some or all of the rings may be part of a fused
ring system. Conjugation length, and therefore absorption and
emission wavelengths, may be controlled with non-aromatic spacer
groups. Non-limiting examples of spacer groups, or repeat units are
--O--, --S--, --NR--, --CR.sub.1R.sub.2--, --(CH.sub.2).sub.n--,
--(CF.sub.2).sub.n--, ester, amide, and the like. The polymers may
be homopolymers, or copolymers. The polymers may be linear,
branched, hyperbranched, dendritic, crosslinked, random, block,
graft, or any structural type. It may be desirable to utilize
dendritic or hyperbranched polymers to channel energy into a
luminescent metal held at or near the core of the polymer
molecules. In this way the luminescent metals are naturally
isolated from one another avoiding concentration effects, and may
be more evenly distributed in the polymer matrix allowing higher
metal concentrations and greater brightness. Examples of polymers
are those having repeat units selected from the groups consisting
of: 6
[0045] where R is independently selected from H, D, F, Cl, Br, I,
alkoxy, aryloxy, alkyl, aryl, alkyl ketone, aryl ketone,
alkylester, arylester, amide, carboxylic acid, fluoroalkyl,
fluoroaryl, polyalkalene oxy, any two of the R groups may be
bridging, m is 0-2, n is 0-3, o is 0-4, p is 0-5, and q is 0-6, A
and B are independently selected from the group consisting of
--O--, --S--, --NR.sub.1--, and --CR.sub.1R.sub.2--,
--CR.sub.1R.sub.2CR.sub.3R.sub.4--, --N.dbd.CR.sub.1--,
--CR.sub.1.dbd.CR.sub.2--, --N.dbd.N--, and --(CO)-- where
R.sub.1-R.sub.4 are H, D, F, alkyl, aryl, alkyleneoxy,
polyalkyleneoxy, alkoxy, aryloxy, fluoroalkyl, and fluoroaryl, two
of the R groups may be bridging, m is 0-2, n is 0-3, o is 0-4, p is
0-5, q is 0-6, and r is 0-7, and E is selected from the group
consisting of O, NH, and S, and one or more fluorescent metal
ions.
[0046] The molecular weight (MW) of the organic matrix, or aromatic
matrix, or aromatic hydrocarbon matrix, will greatly influence the
properties of the device and the ease of fabrication of the device.
Polymers are used as matrices partly because polymer may be cast
into thin films by spin coating, a relatively low cost method.
Other methods, such as screen-printing and ink jet printing, also
require controlled viscosity of the solution carrying the materials
to be printed. Polymers are very effective at controlling the
viscosity by adjusting their MW and concentration. The MW of the
conjugated polymers will also have an influence on conductivity of
the resulting film. The MW should be high, preferably greater than
about 30,000 Dalton, more preferably greater than about 50,000
Dalton, even more preferably greater than about 100,000 Dalton, and
yet more preferably greater than about 150,000 Dalton, and most
preferably greater than about 200,000 Dalton as measured by gel
permeation chromatography (GPC) using techniques well known in the
art and referenced against polystyrene standards. A high MW will
aid in spin coating and printing operations. A high MW will also
prevent the material from crystallizing in use, which is
detrimental to device performance.
[0047] The solution viscosity may also be used as a relative
measure of MW. The viscosity may be measured, for example, by using
an Ubbelohde viscometer to find the specific viscosity at several
concentrations and extrapolating the intrinsic viscosity. The
intrinsic viscosity of the rigid and semi-rigid polymers of the
present invention is preferably greater than 0.8 dL/g, more
preferably greater than 1 dL/g, even more preferably greater than
about 1.5 dL/g, and most preferably greater than about 2 dL/g.
Intrinsic viscosity greater than 3 dL/g may also be desirable in
certain cases. The viscosity of polymers that are not fully
conjugated and having non-aromatic spacer groups may be lower,
preferably greater than 0.3 dL/g, more preferably greater than 0.5
dL/g, and most preferably greater than 0.6 dL/g. Inherent viscosity
is sometimes used as a simpler measure than intrinsic viscosity.
For the purposes of the present invention, inherent viscosity of
greater than 1 is preferred, more preferably greater than 1.5, even
more preferably greater than 2 dL/g, for rigid or highly conjugated
polymers. Lower inherent viscosity is preferred for non-rigid,
non-fully conjugated polymers, e.g., 0.3 dL/g, more preferably
greater than 0.5 dL/g, and most preferably greater than 0.6
dL/g.
[0048] A polymer matrix may be thermoplastic or thermoset. It may
be desirable to use a crosslinked or thermoset type polymer to
improve the stability of an EL layer. In this case the metal ion or
complex is mixed with a polymer precursor, preferably forming a
homogeneous mixture, which is then cured using any means known in
the art, including, but not limited to, thermal, UV, e-beam,
microwave, photo, and chemical curing. For example, a highly
aromatic bisepoxide is blended with a (optionally highly aromatic)
hardener, and a lanthanide metal complex bearing aromatic groups.
The ligands on the metal complex are chosen such that the metal
complex remains homogeneously distributed during and after curing
the epoxy and do not phase separate. The ligands may also contain
thermosetting groups, for example, a ligand bearing an epoxy group,
which will become part of the polymer matrix on curing. The ligands
are also chosen such that energy transfer from excited states of
segments of the epoxy chain to the metal complex or ion is
efficient. The epoxy/hardener/lanthanide metal mixture is then
applied as needed, for example, as a thin film, and cured. It may
be desirable to include a solvent in the epoxy/hardener/lanthanide
metal mixture to aid film formation, which solvent is removed
before, during, or after curing. Similarly, other thermosetting
systems may be used, including but not limited to, cyanate ester,
ethynyl, maleimide, nadimide, olefin/vulcanizer, phenolic,
phenyethynyl, silicone, styrenic, urethane, and the like.
[0049] The matrix may be oligomeric, that is relatively short chain
of repeat units. Oligomers may be desired over polymers to achieve
lower melt viscosity or ease of synthesis. Oligomers have
advantages over small molecules in that oligomers are more readily
processed to give amorphous films.
[0050] The matrix may also be composed of small molecules. It is
preferable to use molecules or mixtures of molecules that can be
processed into amorphous or glassy films. For example, it is known
in the art that spiro type molecules such as 22 (J. Salbeck, J.
Bauer, and F. Weissortel, Polymer Preprints, 38, (1) 1997), will
form glassy films that are highly fluorescent. The Salbeck et al.
article is incorporated herein by this reference. 7
[0051] A key feature of the molecules reported by Salbeck et al,
are the long arms that disrupt crystallinity and provide
conjugation. Luminescent metal complexes having phenyl, biphenyl,
terphenyl, or quaterphenyl groups, preferably terphenyl or
quaterphenyl groups, will form homogeneous amorphous mixed films
with long arm spiro molecules. The aromatic groups on the long arm
spiro molecule and the aromatic ligands enhance energy transfer to
the metal from the spiro molecule. Spiro molecules, such as 22, may
be combined with fluorescent metal complexes, preferably lanthanide
complexes, to form glassy films that fluoresce predominantly the
color of the fluorescent metal.
[0052] The organic matrix of the present invention may be an
aromatic matrix, preferably an aromatic hydrocarbon matrix,
containing only carbon and hydrogen, and preferably only aromatic
rings. The aromatic rings may be phenyl or phenylene, or fused ring
structures such as naphthalene, anthracene, phenanthrene and the
like. The aromatic hydrocarbon matrix may be composed of discrete
molecules (i.e., having molecules of only a single molecular
weight) or may be oligomeric or polymeric phenylenes (i.e., having
a range of molecular weights). The aromatic hydrocarbon matrix may
be spiro structures such as structure 22, or fluorene containing
structures such as 9,9-diphenylfluorene. The aromatic hydrocarbon
matrix may be a mixture of discrete molecules, oligomers, and/or
polymers. The aromatic matrix may be linear or branched.
Non-limiting examples of an aromatic matrix are
1,3-di(2-benzoxazole)benz- ene, 2,4-diphenylquinoline,
2,3-diphenylquinoxaline,
1,4-di(6-iodo-4-phenylquinolinedi-2-yl)benzene,
6,6'-di(2,4-diphenylquino- line), 4,4'-diphenyl-4,4'dipyridyl,
triphenyltriazine, N,N,N'N'-tetraphenylbenzidine,
poly(4,4'-triphenylamine), tri-1-naphthylamine, polyaniline,
poly(N-phenylaniline), poly(2,3-dioctyl-1,4-thiophene),
poly(2,3-ethylenedioxy-1,4-thiophene) and the like. Non-limiting
examples of discrete aromatic hydrocarbon molecules are terphenyl,
9,9'-diphenylanthracene, pentacene, tetraphenylethylene,
triphenylethylene, triphenylmethane, triphenylene,
tetraphenylbenzene, and the like. Non-limiting examples of
oligomeric or polymeric aromatic hydrocarbon matrices are
poly(phenylphenylene),
poly(phenyl-1,4-phenylene-co-phenyl-1,3-phenylene), hyperbranched
polyphenylene, poly(9,9'-dioctylfluorene), and the like.
[0053] The organic matrix may be chosen to be an electron or hole
transport material. Such materials will have a high electron
mobility, preferably greater than 10.sup.-6 cm.sup.2/V-s, more
preferably greater than 10.sup.-5 cm.sup.2/V-s, and most preferably
greater than 10.sup.-4 cm.sup.2/V-s.
[0054] A function of the matrix, whether polymeric, oligomeric, or
small molecule, is to carry charge (holes and/or electrons) and
excited state energy (excitons). Aromatic, polarizable molecules
will have these properties, to an extent dependent on their
conjugation length, and ability to transfer energy through space;
e.g., Forster coupling; see e.g., "Electroluminescent Materials,"
Blasse and Grabmaier, Chapter 5, 1994, Springer-Verlag, which is
incorporated herein by this reference.
[0055] The effectiveness of a matrix to transfer energy to a metal,
or the effectiveness of a ligand to transfer energy from a matrix
to a metal may be determined by measurement of spectra. The UV-vis
spectrum of the matrix is measured and the extinction coefficient
at 354 nm (or other particular wavelength, 354 is used because it
is easily obtained from a mercury lamp and is in the near UV)
calculated and noted as E.sub.matrix. E.sub.matrix has units of
liter/mole-cm. A series of photoluminescence spectra of the matrix
plus metal complex is taken at a metal complex concentration of 0.1
wt % metal and the quantum yield at the wavelength maximum in the
visible region is calculated for each and noted as Phi.sub.complex.
Phi.sub.complex is unitless. The ratio Phi.sub.complex/E.sub.matrix
is the figure of merit F. The figure of merit F has units of
mole-cm/liter. Systems with higher F are better than those with
lower F. This test may be modified in particular cases, e.g. it may
be desired to use lower concentrations of metal complex to avoid
concentration quenching or higher concentrations to improve
sensitivity. It may be desirable to integrate the photoluminescence
intensity over a finite wavelength range instead of using the
wavelength at maximum intensity (Note the units will change
accordingly). This test measures the combined efficiency of energy
transfer from the excited state of the matrix to the metal (through
ligand or otherwise) and emission from the excited metal.
[0056] The luminescent matrix of the instant invention is useful in
electroluminescent (EL) devices. In an EL device an EL material is
sandwiched between two electrodes and a voltage applied. Typically,
one of the electrodes is a transparent electrode. Examples of
transparent electrodes include, but are not limited to, indium tin
oxide (ITO), antimony tin oxide, doped metal oxides such as doped
zinc oxide, and doped titanium oxide, polyaniline, PEDOT, very thin
metal films such as a 50 nm gold film, and combinations of the
above.
[0057] EL devices may contain additional layers, including, but not
limited to hole transport layers (HTL), electron transport layers
(ETL), conducting polymer layers (CPL), metal layers, and layers to
seal the device from the atmosphere.
[0058] The devices may have mixed layers, for example a layer
comprising a hole transport material and a luminescent material. Or
a layer comprising a hole transport material, a luminescent
material and an electron transport material. One skilled in the art
will know how to select HTL and ETL materials.
[0059] The devices may have graded or gradient layers. That is, the
concentration of a hole transport, a luminescent, or an electron
transport material may vary with distance from the electrode in a
continuous fashion. Graded layers may be prepared by allowing one
layer to diffuse into an underlying layer, or by changing the
composition of the layer as it is being deposited.
[0060] Turning to FIG. 1, there is shown one embodiment of an
electroluminescent device 10 provided in accordance with practice
of the present invention. The electroluminescent device 10 includes
a transparent conductor 12 which acts as a first electrode. A hole
transport layer 14 and an electron transport layer 16 supply holes
and electrons, respectively, to an electroluminescent layer 18. A
second electrode 20 completes the circuit. The electroluminescent
device 10, in this embodiment, is mounted on a substrate 22 which,
in some embodiments, can be glass. Other substrates such as plastic
can be used if desired. The substrates can be transparent,
translucent, or opaque. If the substrate is opaque, the top
electrode is preferably transparent. Turning now to FIG. 2, there
is shown an exploded view of the electroluminescent device 10 of
FIG. 1, where like components are labeled with the reference
numerals of FIG. 1.
[0061] Turning to FIG. 3, there is shown an array of cells of
electroluminescent devices 30 provided in accordance with practice
of the present invention. Each of the electroluminescent devices
comprises two electrodes 32 and 34 with an electroluminescent layer
36-sandwiched therebetween. Optionally, a hole transport layer
and/or an electron transport layer can be provided on each side of
the electroluminescent layer. A driver circuit 40 supplies current
to the top electrodes 32. Current-carrying lines 42 are connected
to the bottom electrodes 34, and address lines 44 are used to
control the current supplied through the driver circuitry 40 and
drivelines 46. Each cell may have a different electroluminescent
material in the layer 36 to thereby emit a different color. The
array shown in FIG. 3 is merely illustrative, and the geometry of
the array provided in accordance with the present invention is not
limited by the arrangement of the drawing.
[0062] Turning now to FIG. 4, there is shown an electroluminescent
device 50 provided in accordance with practice of the present
invention which comprises a bottom electrode 52, a top electrode
54, an electron transport layer 56, and an electroluminescent layer
58 mounted on a substrate 60. In this embodiment, there is no hole
transport layer, and the electrode 54 supplies current through the
electron transport layer 56.
[0063] Turning now to FIG. 5, there is shown yet another embodiment
of an electroluminescent device 70 provided in accordance with
practice of the present invention. The electroluminescent device 70
incorporates a graded electroluminescent layer 72 sandwiched
between electrodes 74 and 76. The electroluminescent device 70 is
supported on a substrate layer 78. In this embodiment, the graded
layer comprises an organic matrix and a luminescent metal ion or
luminescent metal complex, and optionally a hole transport material
and/or an electron transport material. The concentration of the
luminescent metal ion or luminescent metal complex is dependent on
position, for example the concentration may be low, or approach
zero near the electrodes 74 and 76, and be highest at the center of
the layer 72. This arrangement would prevent quenching of
luminescence by the electrodes. Similarly, a gradient of hole
transport material, e.g. varying approximately linearly from zero
near the electrode 74 to the highest near the electrode 76, would
aid in hole transport from electrode 76, but not allow holes to
reach the electrode 74. Similarly, a gradient of electron transport
material from zero near the electrode 76, and highest near the
electrode 74, would aid electron transport.
[0064] In the absence of an electron transport layer and/or a hole
transport layer, the organic matrix comprising the
electroluminescent layer must carry electrons and/or holes
respectively.
EXAMPLE 1
[0065] 8
[0066] Polymer 23 poly-p-(N,N-dimethylamidophenylene) (10 mg) is
prepared (as described in U.S. Pat. No. 5,227,457 Example XV,
incorporated herein by reference) by placing dry nickel chloride
(60 mg., 0.46 mmol), triphenylphosphine (0.917 g, 3.5 mmol),
2,2'-bipyridine (64.7 mg, 0.41 mmol), sodium iodide (0.39 g, 1.44
mmol), and zinc powder (0.92 g, 14.1 mmol) into a 100 ml
round-bottom flask. The flask and its contents are heated to
50.degree. C. for 90 minutes under dynamic vacuum to remove trace
water. Evacuation is discontinued, and argon is admitted to the
flask. Dry dimethylformamide (DMF) (8 ml) is added, and the
temperature is raised to 80.degree. C. Within 5 minutes, the
mixture turns a deep-red color. After stirring for 20 minutes under
argon, a solution of 2,5-dichloro-N,N-dimethylbenzamide (2.016 g,
9.1 mmol) in DMF (5 ml) is added. After 2 hours, the mixture is
cooled to room temperature, then poured into 200 ml of 15% aqueous
HCl and extracted with benzene. The product, as a suspension in
benzene, is washed with 5% HCl. Dichloromethane is added to the
thick, white, benzene suspension to give a slightly cloudy
solution, which is separated from the remaining water and taken to
dryness on a rotary evaporator to give 0.5 g of
poly-p-(N,N-dimethylamidophenylene), a white powder. The polymer 23
was dissolved in 1.5 g N-methyl pyrrolidinone (NMP). Separately 15
mg EuCl.sub.3.6H.sub.2O was dissolved in 1.7 g NMP. The solutions
were mixed and stirred for two minutes at about 120.degree. C. A
portion of this solution was cast onto a microscope slide on a hot
plate in air at 120-130.degree. C. An essentially dry film was
obtained after a few minutes. Upon exposure of this film to long
wavelength UV radiation (.about.366 nm) red luminescence was
observed. As a standard reference, 15 mg of polymer 23 was
dissolved in 1.2 g NMP and cast as above. Upon exposure to long
wavelength UV radiation, bright blue luminescence was observed. The
red luminescence of the polymer 23/Eu.sup.3+ film diminished when
placed in air for an extended period of time. A drop of water was
placed on the film. The region of the film contacted by water
fluoresced blue.
EXAMPLE 2
[0067] 9
[0068] Poly(1,3-(5-dimethylamino)phenylene), 24
[0069] To N,N-dimethyl-3,5-dichloroaniline (1.90 grams, 0.01 mol)
in anhydrous NMP (50 ml) is added
nickel(bistriphenylphosphine)dichloride (0.109 g, 0.167 mmol),
sodium bromide (0.103 g, 1 mmol), and triphenylphosphine (0.262 g,
1 mmol), and zinc dust (1.96 g 0.03 mol) under nitrogen. On
addition of zinc the reaction mixture warms. The temperature is
held between 70.degree. C. and 85.degree. C. using a cooling or
heating bath as needed, for 4 hours. The reaction mixture is then
cooled to below 50.degree. C. and poured into 100 ml of
isopropanol. The coagulated polymer is filtered and re-dissolved in
NMP. The solution is filtered to remove zinc, and coagulated a
second time into isopropanol. The coagulated polymer is filtered
and dried. Polymer 24 poly(1,3-(5-dimethylamino)phenylene) (12 mg)
is dissolved in 1.2 g NMP. 10 mg EuCl.sub.3.6H.sub.2O is dissolved
in 1.2 g NMP. Half of each solution is mixed together and cast as
in Example 1. The other half of polymer PP3 solution is separately
cast and dried. Upon exposure to long wavelength UV radiation, the
film of pure PP3 luminescence blue while the film of the
PP3/Eu.sup.3+ does not luminesce.
EXAMPLE 3
[0070] 10
[0071] Poly(2,5-benzophenone-co-1,4-phenylene-co-1,3-phenylene),
25
[0072] The following compounds were added to a round bottom flask
under a nitrogen purge: 2,5-dichlorobenzophenone (1.51 grams, 6.00
mmol), 1,4-dichlorobenzene (0.88 gram, 6.00 mmol),
1,3-dichlorobenzene (7.06 ml, 48 mmol), NMP (53.9 ml), NaI (0.84
gram, 5.60 mmol), triphenylphosphine (3.15 gram, 13.6 mmol),
nickelbistriphenylphosphinedichloride (0.523 gram, 0.800 mmol), and
Zn dust (5.6 gram, 85.6 mmol). The reaction was heated in an oil
bath set to 65.degree. C. The temperature of the reaction mixture
increased to 81.1.degree. C. and then returned to 65.degree. C. The
reaction mixture was held at 65.degree. C. overnight, after which
time the mixture was coagulated into a mixture of ethanol and
concentrated hydrochloric acid. The coagulated polymer was washed
with hot ethanol and hot acetone and dried. The weight average
molecular weight was determined to be 32,333 by gel permeation
chromatography (GPC). The yield was 5.265 grams of polymer 25
indicating that some impurities were still present in the
coagulated polymer. Films were cast from hot NMP. The films
fluoresce blue under long wave ultraviolet irradiation.
[0073] Polyphenylene polymer 25 20 (mg) is dissolved in 1.5 g NMP.
Separately, 10 mg EuCl.sub.3.6H.sub.2O is dissolved in 1.2 g NMP.
The solutions are mixed and cast as in Example 1. Upon exposure to
UV radiation (366 nm) the typical blue luminescence of polymer 25
is observed with no observable diminution in strength or shift in
color due to the addition of europium salt.
[0074] In Examples 1 and 2, and most notably Example 1, the color
of luminescence of the mixture was altered from the blue color of
the host polymer, most probably due to energy transfer from the
excited state of the polymer to the rare earth metal and the
subsequent emission from the metal ion. The red emission in Example
1 indicates emission only from the excited Eu.sup.3+ ions and the
transfer of energy from the excited state of 23 to the Eu.sup.3+
ions.
[0075] Complexation or coordination of the rare earth ion and the
polymer appears to be important for energy transfer. Polymers 23
and 24 contain amide and amine moieties in their structure while
polymer 25 is purely a hydrocarbon. Complexation of the nitrogen or
oxygen containing polymers seems to facilitate energy transfer. In
Example 3, Polymer 25 does not contain groups that interact
strongly with the europium ion and thus interaction and energy
transfer did not take place. In Example 2 polymer 24 has an amine
side group which may coordinate to a metal ion. Energy was
transferred from the polymer as indicated by quenching of polymer
luminescence, however, luminescence of the europium is not
observed, indicating that other factors may cause quenching of the
rare earth luminescence.
EXAMPLE 4
[0076] Polyfluorene 26.
[0077] 9,9-di-n-butyl-2,7-dibromofluorene 27 is prepared by the
method of Woo, et al, U.S. Pat. No. 5,962,631 the relevant parts of
which are incorporated herein by reference. The GPC molecular
weight of the polymer 27 is 50,000 to 60,000.
[0078] To 27 (4.36 grams, 0.01 mol) in anhydrous NMP (50 ml) is
added nickel(bistriphenylphosphine)dichloride (0.109 g, 0.167
mmol), sodium bromide (0.103 g, 1 mmol), and triphenylphosphine
(0.262 g, 1 mmol), and zinc dust (1.96 g, 0.03 mol) under nitrogen.
On addition of zinc the reaction mixture warms. The temperature is
held between 70.degree. C. and 85.degree. C. using a cooling or
heating bath as needed, for 4 hours. The reaction mixture is then
cooled to below 50.degree. C. and poured into 100 ml of
isopropanol. The coagulated polymer is filtered and redissolved in
NMP. The solution is filtered to remove zinc, and coagulated a
second time into isopropanol. The coagulated polymer 26 is filtered
and dried.
EXAMPLE 5
[0079] Polyfluorene copolymer 28
[0080] 9,9-di-n-butyl-2,7-dibromofluorene 27 is prepared as above
by the method of Woo, et al, U.S. Pat. No. 5,962,631.
[0081]
2,7-dibromofluorene-9-spiro-2'-(1',3',6',9',12',15'-hexaoxacyclohep-
tadecane), 29 11
[0082] To a solution of 2,7-dibromo-9-fluoreneone (33.8 grams, 0.1
mol) in toluene (250 ml), is added penta(ethylene glycol) (23.8
grams, 0.1 mol), and DOWEX.RTM. 50WX4-100 ion-exchange resin (5
grams). The mixture is gently refluxed for 8 hours in a dean-stark
apparatus to remove water, after which time the mixture is cooled
to room temperature and the ion-exchange resin is filtered off. The
solvent is removed by distillation at reduced pressure using a
rotary evaporator. The resulting product may be used as is or
purified by column chromatography.
[0083] Alternatively, the crown ether 29 may be prepared following
the method of Oshima et al, Bull. Chem. Soc. Japan, 59, 3979-3980,
except replacing 9-fluoreneone with 2,7-dibromo-9-fluoreneone.
[0084] To 29 (5.58 grams, 0.01 mol) in anhydrous NMP (50 ml) is
added 27 (4.36 grams, 0.01 mol),
nickel(bistriphenylphosphine)dichloride (0.109 g, 0.167 mmol), and
triphenylphosphine (0.262 g, 1 mmol), and zinc dust (1.96g, 0.03
mol) under nitrogen. On addition of zinc the reaction mixture
warms. The temperature is held between 70.degree. C. and 85.degree.
C. using a cooling or heating bath as needed, for 4 hours. The
reaction mixture is then cooled to below 50.degree. C. and poured
into 100 ml of isopropanol. The coagulated polymer 28 is filtered
and redissolved in NMP. The solution is filtered to remove zinc,
and coagulated a second time into isopropanol. The coagulated
polymer is filtered and dried.
EXAMPLES 6-8
[0085] Polyfluorene Type fluorophors.
[0086] Polyfluorene 28 (10.0 grams) and a metal salt as indicated
in Table 1 are dissolved in 100 ml NMP. The solution is spin-coated
onto an ITO coated glass substrate to a thickness of about 100 nm.
The coated substrate is dried at 100.degree. C. at reduced pressure
for 3 hours. The films fluoresce as indicated in Table 1 when
irradiated at 366 nm. An aluminum layer of a thickness of about 200
nm is evaporated onto the polymer/metal salt film at about
10.sup.-6 torr. Connections were made to the ITO and aluminum layer
with indium-tin solder. A potential is applied to the films with
ITO positive and aluminum negative (forward bias), causing the
devices to emit light of a color corresponding to the
photoluminescence.
1TABLE 1 Example Metal Salt Weight Moles Luminescence Example 6
Tb(NO.sub.3).sub.35H.sub.2O 4.35 grams 0.01 mol Green Example 7
Ce(NO.sub.3).sub.36H.sub.2O 4.34 grams 0.01 mol Blue Example 8
Eu(NO.sub.3).sub.35H.sub.2O 4.28 grams 0.01 mol Red
EXAMPLES 9-11
[0087] Films of Polyfluorene and a Polarizable Fluorescent Metal
Complex.
[0088] Polyfluorene 28 (10.0 grams), and a metal complex as
indicated in Table 2 (dbm is dibenzoylmethane) are dissolved in 100
ml NMP. The solution is spin-coated onto an ITO coated glass
substrate to a thickness of about 100 nm. The coated substrate is
dried at 100.degree. C. at reduced pressure for 3 hours. The films
fluoresce as indicated in Table 2 when irradiated at 366 nm. An
aluminum layer of a thickness of about 200 nm is evaporated onto
the polymer/metal salt film at about 10.sup.-6 torr. The area
covered by the aluminum is controlled using a mask of 1 cm.sup.2
open area. Connections were made to the ITO and aluminum layer with
indium-tin solder. A potential is applied to the films with ITO
positive and aluminum negative (forward bias), causing the devices
to emit light of a color corresponding to the
photoluminescence.
2TABLE 2 Example Metal Complex Weight Moles Luminescence Example 9
Eu(dbm).sub.3 8.25 grams 0.01 mol Red Example 11 Ce(dbm).sub.3 8.13
grams 0.01 mol Blue Example 10 Tb(dbm).sub.3 8.32 gram 0.01 mol
Green
EXAMPLE 12
[0089] Europium doped yttria, Y.sub.2O.sub.3:Eu (100 grams)
(Superior MicroPowders, Albuquerque, NM) is added to a solution of
polymer 23 (100 grams) in NMP (1 liter). The suspension is mixed
well and films are cast onto ITO coated glass substrates to give
films of thickness of about 2 microns. An aluminum contact is
evaporated onto the film through a mask to cover a 1-cm square
section of the film. Under forward bias the film emits red
light.
EXAMPLES 13-16
[0090] Nanocrystalline Phosphor/Polymer Matrix Type
Electroluminescent Systems.
[0091] Nanocrystalline phosphors are prepared according to Ihara et
al, as reported in Society for Information Display, International
Symposium, 1999. The average particle size is 2 to 3 nanometers.
Ten grams of nanocrystalline phosphor is added to 5 grams of
polymer 26 (or polymer 23) in 50 ml of NMP. The resulting
suspensions are spin cast onto ITO coated glass plates to form thin
films between 100 and 500 nanometers. The films fluoresce (PL)
under 366-nm irradiation as tabulated in Table 3. The films are
then coated with aluminum by vacuum evaporation through a mask with
a 5-mm by 10-mm hole. A voltage of 5 to 10 V is applied across the
device with the ITO electrode being positive causing
electroluminescence (EL) as listed in Table 3.
3 TABLE 3 Example Nanocrystal Polymer PL EL Example 13 ZnS:Eu 26
Red Red Example 14 ZnS:Tb 26 Green Green Example 15 ZnS:EuF.sub.3
23 Red Red Example 16 ZnS:TbF.sub.3 26 Green Green
EXAMPLES 17-20
[0092] Polymer/Rare Earth Metal Complexes
[0093] Energy transfer between an aromatic polymer and lanthanide
ions was qualitatively examined. NMP was used as co-solvent for all
mixtures from which films were cast and dried at around 100.degree.
C. in air. Dilute and approximately equivalent concentration
solutions of all species were made in NMP. Desired solution
mixtures were then prepared by mixing of equivalent amounts of the
polymer and metal salt solutions. Films were prepared by casting
these solution mixtures onto slides and drying in air at
.about.100.degree. C. using a hot plate. The dried films were then
excited with long wave UV radiation (366 nm) and the luminescence
observed. Table 4 shows the luminescence properties of the starting
materials. Table 5 summarizes the results for the mixtures.
4 TABLE 4 Material Phase Luminescence/Color Comments 25 Solid Blue
Hazy film 23 Solid Blue Clear film 24 Solid Blue Clear brownish
EuCl.sub.3 Solution Red Clear solution TbCl.sub.3 Solution Green
Clear solution
[0094]
5TABLE 5 Luminescence/ Example # Mixtures Phase Color Comments 17
25 + Eu.sup.3+ Solid Blue Hazy film 18 23 + Eu.sup.3+ Solid Red
Clear film 19 24 + Eu.sup.3+ Solid None Clear brownish 20 23 +
Tb.sup.3+ Solid Weak Blue Clear
[0095] In Examples 18, 19, and 20 the color of the film
fluorescence is altered away from the blue color of the sensitizer
or host polymer, most probably due to energy transfer from the
excited state of the polymer to the rare earth metal and the
subsequent emission from the lattice of the metal ion. This was
most pronounced in Example 18 where the red color indicated
emission only from the excited Eu.sup.3+ ions and the transfer of
energy from the excited state of polymer 23 to the Eu.sup.3+ ions.
In example 19 the fluorescence of the polymer was quenched
indicating energy transfer, however, the Eu fluorescence in the red
was too weak to be visible. In Example 20, the weak blue
fluorescence indicated only partial energy transfer to Tb, and the
green color of Tb fluorescence was not observed. In this set of
experiments the N,N-dimethylamido groups of polymer 23 was most
effective at transferring energy to Eu.sup.3+.
EXAMPLE 21
[0096] Crosslinked Matrix
[0097] The bisglycidylether of 4,4'-biphenyl is mixed with 20 mole
% of 1-naphthylamine, 500 mole % anisole, and 2 mole % of
Eu(acac).sub.3. Optionally, 10 to 50 mole % of a polymer of
structures I through XII is added. The mixture is cast into a film
and heated to 80.degree. C. under reduced pressure causing
simultaneous evaporation of anisole and curing of the epoxy groups.
The cured film fluoresces red.
EXAMPLE 22
[0098] Photocrosslinked Matrix
[0099] Monomers 1-vinylnaphthalene (0.1 mol) and divinylbenzene
(0.005 mol), photoinitiator (0.001 mol), and
tris(8-hydroxyquinolinato)terbium, are mixed and cast as a thin
film by spin coating onto an ITO coated glass substrate. The film
is immediately exposed to 254 run light to activate the
photoinitiator. The film is then heated to 100.degree. C. for 5 min
to remove unreacted monomer. The film fluoresces green. A second
electrode of aluminum is deposited onto the luminescent layer by
sputtering.
EXAMPLE 23
[0100] Photocrosslinked Matrix
[0101] The same as example 22, except that polystyrene (0.05 mol)
is added to the mixture before spin coating to adjust the viscosity
of the mixture.
EXAMPLE 24
[0102] Small Molecule Matrix--Spiro Compound Matrix
[0103] The spiro compound 22 (0.1 mol) is dissolved in a mixture of
toluene (50 ml) and tetrahydrofuran (50 ml) and
tris(benzoylnaphthoylmeth- ane)terbium (0.05 mol) and polystyrene
(0.01 mol) are added. The resulting mixture is spin coated onto the
top of a multilayer structure consisting of glass, ITO, and
tris(4-phenylethynylphenyl)amine cured at 300.degree. C. for 1 hour
under nitrogen (50 nm). The resulting multilayer structure
fluoresces green. A top electrode is formed by evaporation of
aluminum.
[0104] Tris(4-phenylethynylphenyl)amine.
[0105] Tri(4-bromophenyl)amine (0.1 mol) and phenylacetylene (0.3
mol) are allowed to react in NMP (100 ml) with palladiumdiacetate
(0.006 mol), tritolylphosphine (0.012 mol) and triethylamine 0.3
mol) at 80.degree. C. for 16 hours. The triethylammonium bromide is
filtered off and the product is purified by recrystalizaton from
hexane.
EXAMPLE 25
[0106] Monomer 27 (9,9-di-n-butyl-2,7-dibromofluorene) (43.6 gram,
0.1 mol) and 2,7-dibromo-9-fluoreneone (8.45 grams, 0.025 mol) are
polymerized using the conditions of Example 5 to give copolymer 30
having the following structure: 12
[0107] A film is cast from a solution of 30 (1 gram) and
europiumtrichloride hydrate (0.1 gram) in NMP (10 ml). The film
fluoresces red.
EXAMPLE 26. Film containing hole transport agent The method of
Example 1 is repeated except that
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biph-
enyl)-4,4'diamine (TPD) 5 mg is added to the first solution in
addition to polymer 23. The resulting film has a red fluorescence
when irradiated at 366 nm.
EXAMPLE 27
[0108] Poly(para-benzoylmorpholine) 31 is prepared (as described in
U.S. Pat. No. 5,227,457 Example XVII incorporated herein by
reference) by placing anhydrous nickel(II) chloride (50 mg, 0.39
mmol), triphenylphosphine (750 mg, 2.86 mmol), sodium iodide (150
mg, 1.0 mmol), and 325 mesh activated zinc powder (1.2 g, 18 mmol)
into a 25 ml flask under an inert atmosphere along with 5 ml of
anhydrous N-methyl-pyrrolidinone (NMP). This mixture is stirred at
50.degree. C. for about 10 minutes, leading to a deep-red
coloration. A solution of 3 g (11.5 mmol) of
2,5-dichlorobenzoylmorpholine (>99% pure by HPLC analysis) in 10
ml of anhydrous NMP is then added by syringe. After stirring for
about 60 hours, the resulting highly viscous solution is poured
into 100 ml of 1 molar hydrochloric acid in ethanol to dissolve the
excess zinc metal and to precipitate the polymer. This suspension
is filtered, and the precipitate triturated with acetone to afford,
after isolation and drying, 2.2 g (100% yield) of
polyparabenzoylmorpholine as a light tan powder. The inherent
viscosity is about 1.8 dL/g. Polymer 31, 10 mg, is dissolved in 1.5
g NMP. Separately, 15 mg Eu(NO3)3.6H2O and 6 mg phenanthroline are
dissolved in 1.5 g NMP. The solutions are mixed and stirred for two
minutes at 120.degree. C. A portion of the solution is cast onto a
glass plate at 120-130.degree. C., and kept hot until dry, and then
cooled to room temperature. On exposure to 366 nm UV radiation, red
luminescence is observed. A film prepared similarly from a solution
containing polymer 31 alone fluoresces blue.
EXAMPLE 28
[0109] Copoly-{1,4-(benzoylphenylene)}-{1,4-phenylene} 32 is
prepared (as described in U.S. Pat. No. 5,227,457 Example XVII
incorporated herein by reference) by placing anhydrous
bis(triphenylphosphine) nickel(II) chloride (3.75 g; 5.7 mmol),
triphenylphosphine (18 g; 68.6 mmol), sodium chloride (2.0 g, 34.2
mmol), 325 mesh activated zinc powder (19.5 g; 298 mmol), and 250
mL of anhydrous NMP into an oven dried 1-liter flask under an inert
atmosphere. (Activated zinc powder is obtained after 2-3 washings
of commercially available 325 mesh zinc dust with 1 molar hydrogen
chloride in diethyl ether (anhydrous) and drying in vacuo or under
inert atmosphere for several hours at about 100.degree.-120.degree.
C. The resulting powder should be sifted (e.g. a 150 mesh sieve
seems to be satisfactory), to remove the larger clumps that
sometimes form, to assure high activity. This material should be
used immediately or stored under an inert atmosphere away from
oxygen and moisture) this mixture is stirred for about 15 minutes,
leading to a deep-red coloration. A mixture of
2,5-dichlorobenzophenone (45 g; 179 mmol) and 1,4-dichloro-benzene
(2.95 g; 20 mmol) is then added to the flask. The temperature of
the vigorously stirred reaction mixture is held at
60.degree.-70.degree. C. until the mixture thickens (about 30
minutes). Afier cooling the reaction mixture to room temperature
overnight, the resulting viscous solution is poured into 1.2 L of 1
molar hydrochloric acid in ethanol to dissolve the excess zinc
metal and to precipitate the polymer. This suspension is filtered
and the precipitate is washed with acetone and dried to afford
crude resin. The achieve high purity, the crude polymer is
dissolved in about 1.5 L of NMP and coagulated into about 4 L of
acetone, continuously extracted with acetone, and dried to afford
30 g (89% yield) of an off-white powder. The intrinsic viscosity is
4.2 dL/g in 0.05 molar lithium bromide in NMP at 40.degree. C.
[0110] Polymer 32, 1.3 g is reduced using sodium borohydride (1.1
molar equivalent of sodium borohydride for each benzoyl group of
32) in phenethylalcohol, to give polymer 33. Polymer 33 is treated
with an excess of acetic anhydride to esterify the alcohol groups
resulting from the sodium borohydride reduction, to give polymer
34.
[0111] A layer of polymer 34 (about 300 nm thick) is spin cast onto
a glass substrate coated with an indium tin oxide transparent
conductive layer, which has been coated with Baytron P.RTM. (Bayer)
of thickness about 500 nm. A layer of calcium is evaporated on top
of the layer of polymer 34 as a cathode. Finally, a layer of
magnesium is evaporated on top of the calcium to protect the
calcium from air. When a voltage is applied between the indium tin
oxide anode and the calcium cathode, blue light is emitted.
EXAMPLE 29
[0112] Copoly-{1,4-(benzoylphenylene)}-{1,3-phenylene} 35 is
prepared (as described in U.S. Pat. No. 5,654,392 Example 16
incorporated herein by reference) by placing anhydrous
bis(triphenylphosphine) nickel(II) chloride (10 g; 15 mmol),
triphenylphosphine (50 g; 0.19 mole), sodium iodide (15 g; 80
mmol), and 325 mesh activated zinc powder (60 g; 0.92 mole) into a
bottle under an inert atmosphere and added to an oven dried 2-liter
flask containing 800 milliliters of anhydrous NMP, against a
vigorous nitrogen counterflow. This mixture is stirred for about 15
minutes, leading to a deep-red coloration. A mixture of
2,5-dichlorobenzophenone (127 g: 0.51 Mole) and 1,3-dichlorobenzene
(11 ml; 96 mmol) is then added to the flask. After an initial
slight endotherm (due to dissolution of monomer), the temperature
of the vigorously stirred reaction mixture warms to about
80.degree.-85.degree. C. over 30 minutes. After stirring for an
additional 10-15 minutes, the viscosity of the reaction mixture
increases drastically and stirring is stopped. After cooling the
reaction mixture to room temperature overnight, the resulting
viscous solution is poured into 6 L of 1 molar hydrochloric acid in
ethanol to dissolve the excess zinc metal and to precipitate the
polymer. This suspension is filtered, and the precipitate is
continuously extracted with ethanol and then with acetone and dried
to afford 93 g (94% yield) of crude white resin. To achieve high
purity, the crude polymer is dissolved in about 600 mL of methylene
chloride, pressure filtered through 1.2 micron (nominal)
polypropylene fiber filters, coagulated into about 2 liters of
acetone, continuously extracted with acetone, and dried to afford
92 g (93% yield) of a fine white powder. The GPC MW relative to
polystyrene is 150,000-200,000.
[0113] Polymer 35, 2 g is reduced using sodium borohydride (2 molar
equivalent of sodium borohydride for each benzoyl group of 35) in
phenethylalcohol to give polymer 36. Polymer 36 is treated with an
excess of acetic anhydride to esterify the alcohol groups resulting
from the sodium borohydride reduction to give polymer 37. Polymer
37 has a GPC MW of 150,000-200,000 relative to polystyrene. Polymer
37 fluoresces blue when irradiated at 366 nm. A layer of polymer 36
(about 250 nm thick) is spin cast onto a glass substrate coated
with an indium tin oxide transparent conductive layer, which has
been coated with Baytron P.RTM. (Bayer) of thickness about 500 nm.
A layer of calcium is evaporated on top of the layer of polymer 36
as a cathode. Finally, a layer of magnesium is evaporated on top of
the calcium to protect the calcium from air. When a voltage is
applied between the indium tin oxide anode and the calcium cathode,
blue light is emitted.
EXAMPLE 30
[0114] Polymer 37 as prepared in Example 28 above, 1 g, is mixed
with 0.4 g Eu(NO.sub.3).sub.3, 6H.sub.2O and 0.15 g phenanthroline
in 15 ml NMP. This solution is spin cast onto glass plates
pre-coated with indium tin oxide and Baytron P.RTM. Bayer to give a
film of about 200 nm thick. The film fluoresces red when irradiated
at 366 nm. A magnesium/silver cathode is evaporated on top of the
polymer 37 layer on one of the plates. On a second plate, a 100 nm
layer of 2,4-dinaphthyloxodiazole is evaporated onto the layer of
polymer 37, followed by evaporation of a magnesium/silver cathode.
Both devices emit red light when a voltage is applied across the
anode and cathode.
[0115] The above descriptions of exemplary embodiments of
photoluminescent and electoluminescent compositions, the process
for producing such compositions, and the photoluminescent and
electroluminescent devices produced thereby are for illustrative
purposes. Because of variations which will be apparent to those
skilled in the art, the presnt invention is not intended to be
limited to the particular embodiemtns described above. The scope of
the invention is defined in the following claims:
* * * * *