U.S. patent application number 16/200627 was filed with the patent office on 2019-12-19 for luminance and color temperature tunable tandem oled.
The applicant listed for this patent is National Tsing Hua University. Invention is credited to JWO-HUEI JOU, HSIN-FA LIN, CHENG-CHIEH LO, MEENU SINGH.
Application Number | 20190386252 16/200627 |
Document ID | / |
Family ID | 68840590 |
Filed Date | 2019-12-19 |
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United States Patent
Application |
20190386252 |
Kind Code |
A1 |
JOU; JWO-HUEI ; et
al. |
December 19, 2019 |
LUMINANCE AND COLOR TEMPERATURE TUNABLE TANDEM OLED
Abstract
Disclosures of the present invention describe a luminance and
color temperature tunable (LCTT) tandem OLED, which mainly consists
of a transparent conductive substrate, a HTL, a first lighting
unit, a first carrier generation unit, a second lighting unit, a
second carrier generation unit, a third lighting unit, an ETL, and
a cathode electrode. The first lighting unit is designed to emit a
cold-white light, a pure-white light or an orange-white light, the
second lighting unit is designed to emit a warm-white light, and
third lighting unit is designed to emit an orange-white light, a
pure-white light or a cold-white light corresponding to the first
lighting unit. By such arrangement, it is easy for a user to make
the LCTT tandem OLED provide an illumination with user-desirable
color temperature and illuminance by using a control interface to
electrically drive the three lighting units, either individually or
simultaneously.
Inventors: |
JOU; JWO-HUEI; (Hsinchu
City, TW) ; SINGH; MEENU; (New Delhi, IN) ;
LIN; HSIN-FA; (Kaohsiung City, TW) ; LO;
CHENG-CHIEH; (Changhua County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Tsing Hua University |
Hsinchu |
|
TW |
|
|
Family ID: |
68840590 |
Appl. No.: |
16/200627 |
Filed: |
November 26, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 51/0085 20130101;
H01L 27/3209 20130101; H01L 51/508 20130101; H01L 51/5206 20130101;
H01L 51/0037 20130101; H01L 51/5092 20130101; H01L 51/5016
20130101; H01L 51/0072 20130101; H01L 51/0035 20130101; H01L
2251/5376 20130101; H01L 51/5221 20130101; H01L 51/5036 20130101;
H05B 45/20 20200101; H05B 45/60 20200101; H01L 51/5278
20130101 |
International
Class: |
H01L 51/52 20060101
H01L051/52; H01L 51/50 20060101 H01L051/50; H05B 33/08 20060101
H05B033/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2018 |
TW |
107120821 |
Claims
1. A luminance and color temperature tunable tandem OLED,
comprising: a transparent conductive substrate, comprising a
transparent substrate and an anode electrode formed on the
transparent substrate; a hole injection layer formed on the anode
electrode; a first lighting unit, being formed on the hole
injection layer and comprising a first electron transport layer, a
first light emission layer and a first hole transport layer;
wherein the first lighting unit is configured to emit a first
light, and the first light being a cold-white light, a pure-white
light or an orange-white light; a first carrier generation unit,
being formed on the first lighting unit, and having a first
modulation electrode; a second lighting unit, being formed on the
first carrier generation unit, such that the first carrier
generation unit is connected between the second lighting unit and
the first lighting unit wherein the second lighting unit comprises
a second electron transport layer, a second light emission layer
and a second hole transport layer, and being configured to emit a
second light, and the second light being a warm-white light; a
second carrier generation unit, being formed on the second lighting
unit, and having a second modulation electrode; a third lighting
unit, being formed on the second carrier generation unit, such that
the second carrier generation unit is connected between the third
lighting unit and the second lighting unit wherein the third
lighting unit comprises a third electron transport layer, a third
light emission layer and a third hole transport layer, and being
configured to emit a third light, and the third light being an
orange-white light, a pure-white light or a cold-white light
corresponding to the first light; an electron injection layer
formed on the third lighting unit; and a cathode electrode formed
on the electron injection layer; wherein the anode electrode, the
first modulation electrode of the first carrier generation unit,
the second modulation electrode of the second carrier generation
unit, and the cathode electrode are configured for being
electrically connected to an external controlling and driving
unit.
2. The luminance and color temperature tunable tandem OLED of claim
1, wherein each of the first light emission layer, the second light
emission layer and the third light emission layer comprises at
least one host material and at least two guest dyes.
3. The luminance and color temperature tunable tandem OLED of claim
1, wherein each of the first light emission layer, the second light
emission layer and the third light emission layer comprises at
least one host material and at least one guest dye.
4. The luminance and color temperature tunable tandem OLED of claim
1, wherein each of the first light emission layer, the second light
emission layer and the third light emission layer comprises two
host materials and at least one guest dye, and the two host
materials being separated by a carrier modulation film.
5. The luminance and color temperature tunable tandem OLED of claim
1, wherein all the first electron transport layer, the second
electron transport layer and the third electron transport layer has
hole blocking function.
6. The luminance and color temperature tunable tandem OLED of claim
1, wherein all the first hole transport layer, the second hole
transport layer and the third hole transport layer has electron
blocking function.
7. The luminance and color temperature tunable tandem OLED of claim
1, wherein the first carrier generation unit comprises: a first
carrier generation layer formed on the first lighting unit; and a
second carrier generation layer, being formed on the first
modulation electrode, such that the first modulation electrode is
connected between the first carrier generation layer and the second
carrier generation layer.
8. The luminance and color temperature tunable tandem OLED of claim
7, wherein the second carrier generation unit comprises: a third
carrier generation layer formed on the second lighting unit; and a
fourth carrier generation layer, being formed on the second
modulation electrode such that the second modulation electrode is
connected between the third carrier generation layer and the fourth
carrier generation layer.
9. The luminance and color temperature tunable tandem OLED of claim
8, wherein both the first carrier generation layer and the third
carrier generation layer are made of an n-type carrier generation
material.
10. The luminance and color temperature tunable tandem OLED of
claim 8, wherein both the first carrier generation layer and the
third carrier generation layer are made of an electron injection
material.
11. The luminance and color temperature tunable tandem OLED of
claim 8, wherein both the second carrier generation layer and the
fourth carrier generation layer are made of a p-type carrier
generation material.
12. The luminance and color temperature tunable tandem OLED of
claim 8, wherein both the second carrier generation layer and the
fourth carrier generation layer are made of a hole injection
material.
13. (canceled)
14. The luminance and color temperature tunable tandem OLED of
claim 1, being applied in an illuminance device or a display device
for being used as at least one principle lighting element.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to the technology field of
lighting devices, and more particularly to a luminance and color
temperature tunable tandem OLED.
2. Description of the Prior Art
[0002] It is known that organic light emitting diode (OLED) was
initially invented and proposed by Eastman Kodak Company through a
vacuum evaporation method. Tang and VanSlyke working for Kodak
Company deposited an electron transport material (ETL) such as Alq3
on a transparent indium tin oxide (abbreviated as ITO) glass,
thereby forming with an organic layer of aromatic diamine on the
ITO glass. Consequently, Tang and VanSlyke further completed the
fabrication of an organic electroluminescent (EL) device by letting
a metal electrode be vapor-deposited onto the ETL layer. The
organic EL device does nowadays become a new generation lighting
device or display because of high brightness, fast response speed,
light weight, compactness, true color, no difference in viewing
angles, without using any backlight plates, and low power
consumption.
[0003] An ideal white light OLED is demanded to exhibit high
luminance and outstanding luminous efficiency in the case of having
low current density, and is also demanded to show the same or
similar spectral characteristics even if a driving current thereof
is modulated in a specific range. It needs to further explain that,
an acceptable high current density would be configured to drive a
white light OLED when the white light OLED is applied to be
principle lighting elements of an illuminance device. However,
practical use cases of the illuminance device using the white light
OLEDs as lighting elements thereof reveal that, the white light
OLED would be subject to thermal degradation after being driven by
the high current density for a long time. As a result, the lifetime
of the white light OLED is hence shorten.
[0004] To overcome this critical issue, Kido et al. reported a
tandem OLED comprising multiple light emission units (LEUs)
vertically stacked to each other. FIG. 1 shows a cross-sectional
view of a conventional tandem OLED. The tandem OLED 1' comprises: a
substrate 10', an anode electrode 11', a hole injection layer (HIL)
12', a first hole transport layer (HTL) 13', a blue light emission
layer 14', a first electron transport layer (ETL) 15', a first
connection layer 16', a second HTL 17', a green emission layer 18',
a second ETL 19', a second connection layer 1A', a third HTL 1B, a
red emission layer 1C', a third ELT 1D, an electron injection layer
(EIL) 1E', and a cathode electrode 1F'.
[0005] Compared to the traditional white light OLED, the tandem
OLED 1' exhibits higher brightness under the driving of an
identical current density, such that the tandem OLED 1' has a
longer lifetime than that of the traditional white light OLED.
However, inventors of the present invention find that the tandem
OLED 1' still shows some drawbacks in practical use, listed as
follows: [0006] (1) From FIG. 1, it is understood that, because the
tandem OLED 1' mainly comprises a first light emission unit LEU1'
consisting of the first HTL 13', the blue light emission layer 14'
and the first ETL 15', a second light emission unit LEU2'
consisting of the second HTL 17', the green light emission layer
18' and the second ETL 19', and a third light emission unit LEU3'
consisting of the third HTL 1B', the red light emission layer 1C'
and the third ETL 1D', a driving voltage for the tandem OLED 1'
must be correspondingly increased with the adding of the number of
the LEUs. [0007] (2) FIG. 2 shows a CIE chromaticity diagram. Three
CIE coordinates of a red light, a green light and a blue light
respectively emitted from the first light emission unit LEU1', the
second light emission unit LEU2' and the third light emission unit
LEU3' of the tandem OLED 1' are labeled on the CIE chromaticity
diagram. However, owing to the fact that the three light emission
unit (LEU1', LEU2' and LEU3') cannot be driven individually, it is
difficult or impossible to make the color temperature and luminance
of the tandem OLED 1' be tunable by using a particularly-designed
electronic circuit.
[0008] From above descriptions, it is clear and understood that how
to improve or re-design the tandem OLED 1' so as to produce a
luminance and color temperature tunable tandem OLED has now became
an important issue. Accordingly, inventors of the present
application have made great efforts to make inventive research so
as to eventually provide a luminance and color temperature tunable
tandem OLED.
SUMMARY OF THE INVENTION
[0009] The primary objective of the present invention is to provide
a luminance and color temperature tunable tandem OLED, mainly
comprising: a transparent conductive substrate, a HTL, a first
lighting unit, a first carrier generation unit, a second lighting
unit, a second carrier generation unit, a third lighting unit, an
ETL, and a cathode electrode. In the present invention, the first
lighting unit, the second lighting unit and the third lighting unit
are particularly designed to be capable of emitting a first light,
a second light and a third light, either individually or
simultaneously. The first light can be a cold-white light, a
pure-white light or an orange-white light, and the second light is
a warm-white light either. It is worth noting that, the third light
would be an orange-white light, a pure-white light or a cold-white
light corresponding to the first light during the operation of the
luminance and color temperature tunable tandem OLED. By such
arrangement, it is easy for a user to make the luminance and color
temperature tunable tandem OLED provide an illumination with
user-desirable color temperature and illuminance by operating a
controlling and driving unit to electrically drive the three
lighting units, either individually or simultaneously.
[0010] In order to achieve the primary objective of the present
invention, the inventor of the present invention provides one
embodiment for the luminance and color temperature tunable tandem
OLED, comprising: [0011] a transparent conductive substrate,
comprising a transparent substrate and an anode electrode formed on
the transparent substrate; [0012] a hole injection layer formed on
the anode electrode; [0013] a first lighting unit, being formed on
the hole injection layer and comprising a first electron transport
layer, a first light emission layer and a first hole transport
layer; wherein the first lighting unit is configured to emit a
first light, and the first light being a cold-white light, a
pure-white light or an orange-white light; [0014] a first carrier
generation unit formed on the first lighting unit; [0015] a second
lighting unit, being formed on the first carrier generation unit
and comprising a second electron transport layer, a second light
emission layer and a second hole transport layer; wherein the
second lighting unit is configured to emit a second light, and the
second light being a warm-white light; [0016] a third carrier
generation unit formed on the second lighting unit; [0017] a third
lighting unit, being formed on the second carrier generation unit
and comprising a third electron transport layer, a third light
emission layer and a third hole transport layer; wherein the third
lighting unit is configured to emit a third light, and the third
light being an orange-white light, a pure-white light or a
cold-white light corresponding to the first light; [0018] an
electron injection layer formed on the third lighting unit; and
[0019] a cathode electrode formed on the electron injection
layer.
[0020] In the embodiment of the CTT tandem OLED, the first carrier
generation unit comprises: [0021] a first carrier generation layer
formed on the first lighting unit; [0022] a first modulation
electrode formed on the first carrier generation layer; and [0023]
a second carrier generation layer formed on the first modulation
electrode.
[0024] In the embodiment of the CTT tandem OLED, the second carrier
generation unit comprises: [0025] a third carrier generation layer
formed on the second lighting unit; [0026] a second modulation
electrode formed on the third carrier generation layer; and [0027]
a fourth carrier generation layer formed on the second modulation
electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention as well as a preferred mode of use and
advantages thereof will be best understood by referring to the
following detailed description of an illustrative embodiment in
conjunction with the accompanying drawings, wherein:
[0029] FIG. 1 shows a cross-sectional view of a conventional tandem
OLED;
[0030] FIG. 2 shows a CIE chromaticity diagram;
[0031] FIG. 3 shows a data plot of color temperature versus power
efficiency;
[0032] FIG. 4 shows a cross-sectional view of a luminance and color
temperature tunable tandem OLED according to the present
invention;
[0033] FIG. 5 shows a cross-sectional view of a first lighting
unit;
[0034] FIG. 6 shows a cross-sectional view of a second lighting
unit;
[0035] FIG. 7 shows a cross-sectional view of a third lighting
unit;
[0036] FIG. 8 shows an energy band diagram of the first lighting
unit;
[0037] FIG. 9 shows a CIE chromaticity diagram;
[0038] FIG. 10 shows an energy band diagram of the second lighting
unit;
[0039] FIG. 11 shows a cross-sectional view of the third lighting
unit;
[0040] FIG. 12 shows a cross-sectional view of a first carrier
generation unit; and
[0041] FIG. 13 shows a cross-sectional view of a second carrier
generation unit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] To more clearly describe a luminance and color temperature
tunable tandem OLED according to the present invention, embodiments
of the present invention will be described in detail with reference
to the attached drawings hereinafter.
[0043] The present invention discloses a luminance and color
temperature tunable tandem OLED, which can be applied in an
illuminance device or a display device for being used as at least
one principle lighting element. Before starting to clearly describe
the luminance and color temperature tunable tandem OLED of the
present invention, it needs to explain the classification of
orange-white light, pure-white, and cold-white light. Please refer
to following Table (1), a specific light provided by a specific
lighting device certainly has a corresponding light
classification.
TABLE-US-00001 TABLE 1 Color temperature Light classification
<2,500 K Orange-white light 2,500-5,500 K Warm-white light
5,500-6,500 K Pure-white light >6,500 K Cold-white light
[0044] With reference to FIG. 4, there is provided a
cross-sectional view of a luminance and color temperature tunable
tandem OLED according to the present invention. The luminance and
color temperature tunable tandem OLED 1 comprises: a transparent
conductive substrate comprising a transparent substrate 10 and an
anode electrode 11 formed on the transparent substrate 10, a hole
injection layer 12 formed on the anode electrode 11, a first
lighting unit EMU1 formed on the hole injection layer 12, a first
carrier generation unit CGU1 formed on the first lighting unit
EMU1, a second lighting unit EMU2 formed on the first carrier
generation unit CGU1, a third carrier generation unit CGU3 formed
on the second lighting unit EMU2, a third lighting unit EMU3 formed
on the second carrier generation unit CGU2, an electron injection
layer 13 formed on the third lighting unit EMU3, and a cathode
electrode 14 formed on the electron injection layer 13.
[0045] The main technology feature of the present invention is to
make the first lighting unit EMU1, the second lighting unit EMU2
and the third lighting unit EMU3 emit a first light, a second light
and a third light, either individually or simultaneously. According
to the particular design of the present invention, the first light
can be a cold-white light, a pure-white light or an orange-white
light, and the second light is a warm-white light either. It is
worth noting that, the third light would be an orange-white light,
a pure-white light or a cold-white light corresponding to the first
light during the operation of the luminance and color temperature
tunable tandem OLED 1. Briefly speaking, the luminance and color
temperature tunable tandem OLED 1 of the present invention is
configured to simultaneously emit an orange-white light, a
warm-white light and a pure-white light (or a cold-white light).
Herein, it needs to emphasize that the present does not
particularly limit the material composition or formula of the first
lighting unit EMU1, the second lighting unit EMU2 and the third
lighting unit EMU3, the reason is that engineers skilled in
development and manufacture of OLED device should be able to
fabricate the same lighting units capable of emitting orange-white
light, warm-white light and/or pure-white light according to their
own material composition or formula.
[0046] FIG. 5, FIG. 6 and FIG. 7 show different cross-sectional
views of the first lighting unit, the second lighting unit and the
third lighting unit. From FIG. 5, FIG. 6 and FIG. 7, it is
understood that the first lighting unit EMU1 comprises a first
electron transport layer (ETL) 17-1, a first light emission layer
(EML) 16-1 and a first hole transport layer (HTL) 15-1, the second
lighting unit EMU2 comprises a second electron transport layer
(ETL) 17-2, a second light emission layer (EML) 16-2 and a second
hole transport layer (HTL) 15-2, and the third lighting unit EMU3
comprises a third electron transport layer (ETL) 17-3, a third
light emission layer (EML) 16-3 and a third hole transport layer
(HTL) 15-3. For making the three lighting units (EMU1, EMU2 and
EMU3) able to exhibit outstanding luminous efficiency, it is
preferably to make all the first electron transport layer 17-1, the
second electron transport layer 17-2 and the third electron
transport layer 17-3 by using an electron transport material with
hole blocking function, and to simultaneously fabricate all the
first hole transport layer 15-1, the second hole transport layer
15-2 and the third hole transport layer 15-3 by using a hole
transport material with electron blocking function.
[0047] Continuously referring to FIG. 5, and please simultaneously
refer to FIG. 8, which illustrate an energy band diagram of the
first lighting unit. The first lighting unit EMU1 of the luminance
and color temperature tunable tandem OLED 1 can be designed to
comprise one host material and three guest dyes. Basic information
of the constituting material of the first lighting unit EMU1 are
provided in following Table (2).
TABLE-US-00002 TABLE 2 Constituting layers Manufacturing materials
First HTL poly(3,4-ethylenedioxythiophene) polystyrene sulfonate
15-1 (PEDOT:PSS) Host material 4,4'-Bis(N-carbazolyl)-1,1'-biphenyl
(CBP) Guest dye Tris(2-phenylquinoline)iridium(III) (red)
(Ir(2-phq).sub.3) Guest dye
Bis[5-methyl-7-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-
(green) one]iridium(picolinate) (CF.sub.3BNO) Guest dye
Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2carboxypyridl)iridium(III-
)) (blue) (FIrpic) First ETL
2,2',2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) 17-1
(TPBi)
[0048] It needs to further explain that the red guest dye of
Ir(2-phq).sub.3, the green guest dye of CF.sub.3BNO, and the blue
guest dye of Flrpic are doped in the host material by 0.6 wt %, 0.2
wt % and 8 wt %, respectively. On the other hand, FIG. 9 shows a
CIE chromaticity diagram. From FIG. 9, it is found that the
orange-white light emitted from the first lighting unit EMU1 has a
CIE coordinate of (0.5, 0.44). It is worth particularly emphasizing
that, although FIG. 5 depicts that the first EML 16-1 of the first
lighting unit EMU1 has a single-layer structure, the construction
of the first EML 16-1 does not be limit to be the single-layer
structure. For example, U.S. Pat. No. 8,809,848 B1 has disclosed
that a light emission layer can be particular design to has a
multi-layer structure, therefore such light emission layer is able
to emit a full-band and high-CRI light. On the other hand, U.S.
Patent Publication No. 2012/049166 A1 has disclosed that a light
emission unit can be particular design to has a three-layer
structure including two emission layers and one carrier modulation
layer formed between the two emission layers.
[0049] Continuously referring to FIG. 6, and please simultaneously
refer to FIG. 10, which illustrate an energy band diagram of the
second lighting unit. The second lighting unit EMU2 of the
luminance and color temperature tunable tandem OLED 1 can be
designed to comprise one host material and three guest dyes. Basic
information of the constituting material of the second lighting
unit EMU2 are provided in following Table (3).
TABLE-US-00003 TABLE 3 Constituting layers Manufacturing materials
Second HTL poly(3,4-ethylenedioxythiophene) polystyrene sulfonate
15-2 (PEDOT:PSS) Host material 4,4'-Bis(N-carbazolyl)-1,1'-biphenyl
(CBP) Guest dye Tris(2-phenylquinoline)iridium(III) (red)
(Ir(2-phq).sub.3) Guest dye
Bis[5-methyl-7-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-
(green) 6-one]iridium(picolinate) (CF.sub.3BNO) Guest dye
Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2carboxypyridl)iridium(III-
)) (blue) (FIrpic) Second ETL
2,2',2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) 17-2
(TPBi)
[0050] It needs to further explain that the red guest dye of
Ir(2-phq).sub.3, the green guest dye of CF.sub.3BNO, and the blue
guest dye of Flrpic are doped in the host material by 0.6 wt %, 0.4
wt % and 14 wt %, respectively. Moreover, it is able to find that
the warm-white light emitted from the second lighting unit EMU2 has
a CIE coordinate of (0.42, 0.43).
[0051] Continuously referring to FIG. 7, and please simultaneously
refer to FIG. 11, which illustrate a cross-sectional view of the
third lighting unit. The third lighting unit EMU3 of the luminance
and color temperature tunable tandem OLED 1 can be designed to
comprise one host material and three guest dyes. Basic information
of the constituting material of the third lighting unit EMU3 are
provided in following Table (4).
TABLE-US-00004 TABLE 4 Constituting layers Manufacturing materials
Third HTL poly(3,4-ethylenedioxythiophene) polystyrene sulfonate
15-3 (PEDOT:PSS) Host material 4,4'-Bis(N-carbazolyl)-1,1'-biphenyl
(CBP) Guest dye
Bis[2-(2'-benzothienyl)-pyridinato-N,3'](acetylacetonate) (red)
iridium (III) (Btp.sub.2Ir(acac)) Guest dye
Tris[2-phenylpyridinato-C2,N]iridium(III) (green) (Ir(ppy).sub.3)
Guest dye
Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2carboxypyridl)iridium(III-
)) (blue) (FIrpic) Third ETL Tris(8-hydroxyquinoline) aluminum 17-3
(Alq.sub.3)
[0052] It needs to further explain that the red guest dye of
Btp.sub.2Ir(acac), the green guest dye of Ir(ppy).sub.3, and the
blue guest dye of Flrpic are doped in the host material by 0.35 wt
%, 0.4 wt % and 12 wt %, respectively. Moreover, it is able to find
that the pure-white light emitted from the third lighting unit EMU3
has a CIE coordinate of (0.36, 0.37).
[0053] FIG. 4 also depicts that the first carrier generation unit
CGU1 is disposed between the first lighting unit EMU1 and the
second lighting unit EMU2, and the second carrier generation unit
CGU2 is disposed between the second lighting unit EMU2 and the
third lighting unit EMU3. FIG. 12 and FIG. 13 further show
different cross-sectional views of the first carrier generation
unit and the second carrier generation unit. In the present
invention, the first carrier generation unit CGU1 comprises a first
carrier generation layer CGf1 formed on the first lighting unit
EMU1, a first modulation electrode ME1 formed on the first carrier
generation layer CGf1, and a second carrier generation layer CGf1
formed on the first modulation electrode ME1. Moreover, the second
carrier generation unit CGU2 comprises a third carrier generation
layer CGf3 formed on the second lighting unit EMU2, a second
modulation electrode ME2 formed on the third carrier generation
layer CGf3, and a fourth carrier generation layer CGf4 formed on
the second modulation electrode ME2.
[0054] Both the first carrier generation layer CGf1 and the third
carrier generation layer CGf3 can be made of a n-type carrier
generation material, such as poly(ethylene glycol) dimethyl ether
(PEGDE). On the contrary, both the second carrier generation layer
CGf2 and the fourth carrier generation layer CGf4 are made of a
p-type carrier generation material like NPB doped with F4-TCNQ. In
which, NPB is N'-Bis(naphthalen-l-yl)-N,N'-bis(phenyl)benzidine,
and F4-TCNQ is
2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane. On the other
hand, an electron injection material can also be adopted for use in
the fabrication of the first carrier generation layer CGf1 and the
third carrier generation layer CGf3, a hole injection material can
also be used for making the second carrier generation layer CGf2
and the fourth carrier generation layer CGf4.
[0055] Please refer to FIG. 4, FIG. 12 and FIG. 13 again. According
to the particular design of the present invention, a controlling
and driving unit 2 is provided so as to be electrically connected
to the anode electrode 11, the first modulation electrode ME1 of
the first carrier generation unit CGU1, the second modulation
electrode ME2 of the second carrier generation unit CGU2, and the
cathode electrode 14. By such arrangement, it is easy for a user to
make the luminance and color temperature tunable tandem OLED 1
provide an illumination with user-desirable color temperature and
illuminance by using an user interface of the controlling and
driving unit 2 to electrically drive the three lighting units
(EMU1, EMU2 and EMU3), either individually or simultaneously.
[0056] For instance, in the case of the fact that the first
lighting unit EMU1, the second lighting unit EMU2 and the third
lighting unit EMU3 are respectively design to a high color
temperature lighting element, a middle color temperature lighting
element and a low color temperature lighting element, the
controlling and driving unit 2 is configured for supplying a
positive bias voltage to the anode electrode 11 and the cathode
electrode 14 so as to drive the three lighting units (EMU1, EMU2
and EMU3) to generate three different emission lights. In this
case, by operating the controlling and driving unit 2 to supply a
negative bias voltage to the first modulation electrode ME1 and/or
the second modulation electrode ME2, the luminance and color
temperature tunable tandem OLED 1 is hence controlled to provide an
illumination with user-desirable color temperature and illuminance
because the light emission of the first lighting unit EMU1, the
second lighting unit EMU2, and/or the third lighting unit EMU3 are
conditionally inhibited, either individually or simultaneously.
[0057] Therefore, through above descriptions, the luminance and
color temperature tunable tandem OLED 1 proposed by the present
invention has been introduced completely and clearly; in summary,
the present invention includes the advantages of:
[0058] (1) The present invention provides a luminance and color
temperature tunable tandem OLED, which comprises a transparent
conductive substrate, a HTL 12, a first lighting unit EMU1, a first
carrier generation unit CGU1, a second lighting unit EMU2, a second
carrier generation unit CGU2, a third lighting unit EMU3, an ETL
13, and a cathode electrode 14. In the present invention, the first
lighting unit EMU1, the second lighting unit EMU2 and the third
lighting unit EMU3 are particularly designed to be capable of
emitting a first light, a second light and a third light, either
individually or simultaneously. The first light can be a cold-white
light, a pure-white light or an orange-white light, and the second
light is a warm-white light either. It is worth noting that, the
third light would be an orange-white light, a pure-white light or a
cold-white light corresponding to the first light during the
operation of the luminance and color temperature tunable tandem
OLED 1. By such arrangement, it is easy for a user to make the
luminance and color temperature tunable tandem OLED 1 provide an
illumination with user-desirable color temperature and illuminance
by operating the controlling and driving unit 2 to electrically
drive the three lighting units (EMU1, EMU2 and EMU3), either
individually or simultaneously.
[0059] The above description is made on embodiments of the present
invention. However, the embodiments are not intended to limit scope
of the present invention, and all equivalent implementations or
alterations within the spirit of the present invention still fall
within the scope of the present invention.
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