Patent Application
20070285001
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
Referring to
A first electrode such as an anode electrode 120 is formed on the substrate 110, and can be a transparent electrode, metal electrode, or combinations thereof, comprising indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), zinc oxide (ZnO), Li, Mg, Ca, Al, Ag, In, Au, Ni, Pt, or alloys thereof, formed by a method such as sputtering, electron beam evaporation, thermal evaporation, or chemical vapor deposition.
An electroluminescent layer 130 is formed on the anode electrode 120, wherein the electroluminescent layer 130 at least comprises a light emitting layer 131, and can further comprises a hole injection layer 132, a hole transport layer 133, an electron transport layer 134, and an electron injection layer 135, as shown in
Still referring to
The composite electrode structure 140 can comprise a layer containing alkali or alkaline earth compounds 142 and a metal oxide layer or semiconductor layer 144. Wherein the alkali or alkaline earth compound can have carbonyl group or fluorine. The alkali or alkaline earth compound can comprise a fluoride containing Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, or Ba, such as NaF, KF, RbF, CsF, BeF2, MgF2, CaF2, SrF2, or BaF2. Furthermore, the alkali or alkaline earth compound can comprise a carbonyl compound containing Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, or Ba, such as Li2CO3, LiCO3, Na2CO3, NaCO3, K2CO3, KCO3, Rb2CO3, RbCO3, Cs2CO3, CsCO3, BeCO, BeCO3, MgCO, MgCO3, CaO, Ca2CO3, CaCO3, SrCO, SrCO3, BaCO, or BaCO3. It should be noted that the layer containing alkali or alkaline earth compound can be further doped with an electron transport material, such as Alq3, BeBq2, TPBI, PBD, or TAZ.
The metal oxide layer can comprise oxide of transition metal, wherein the transition metal comprises atoms of Group IB, Group IIB, Group IVB, Group VB, Group VIB, or Group VIIIB, such as oxide of V, W. or Mo. In some embodiments, the metal oxide layer can comprise WO, W2O3, WO2, WO3, W2O5, VO, V2O3, VO2, V2O5, MoO, Mo2O3, MoO2, MoO3, or Mo2O5.
The semiconductor layer can comprise Si, Ge, GaAs, SiC, or SiGe. In an embodiment of the invention, the semiconductor layer is a non-doped semiconductor layer. Furthermore, the semiconductor layer comprises a n-type (B) doping ions (P, As, Sb) or p-type ions doping semiconductor layer.
A first electrode such as an anode electrode 220 is formed on the substrate 210, and can be a transparent electrode, metal electrode, or combinations thereof, comprising indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), zinc oxide (ZnO), Li, Mg, Ca, Al, Ag, In, Au, Ni, Pt, or alloys thereof, formed by a method such as sputtering, electron beam evaporation, thermal evaporation, or chemical vapor deposition. A first electroluminescent unit 230 is formed on the anode electrode 220, wherein the first electroluminescent unit 230 at least comprises a light emitting layer 231, and can further comprise a hole injection layer 232, a hole transport layer 233, an electron transport layer 234, and an electron injection layer 235, as shown in
Still referring to
The metal oxide layer can comprise oxide of transition metal, wherein the transition metal comprises atoms of Group IB, Group IIB, Group IVB, Group VB, Group VIB, or Group VIIIB, such as oxide of V, W, or Mo. In some embodiments, the metal oxide layer can comprise WO, W2O3, WO2, WO3, W2O5, VO, V2O3, VO2, V2O5, MoO, Mo2O3, MoO2, MoO3, or MO2O5.
The semiconductor layer can comprise Si, Ge, GaAs, SiC, or SiGe. In an embodiment of the invention, the semiconductor layer is a non-doped semiconductor layer. Furthermore, the semiconductor layer comprises a n-type (B) doping ions (P, As, Sb) or p-type ions doping semiconductor layer.
A second electroluminescent unit 250 is formed on the connecting electrode structure 240, and the second electroluminescent unit 250 at least comprises a light emitting layer 231, and can further comprise a hole injection layer 232, a hole transport layer 233, an electron transport layer 234, and an electron injection layer 235. Finally, a cathode 260 is formed on the second electroluminescent unit 250. It should be noted that the plurality of electroluminescent units can exhibit the same emission color, resulting in a tandem organic electroluminescent diode 200 with red, blue, or green emission. Further, the plurality of electroluminescent units can exhibit different emission colors, thus, a tandem organic electroluminescent diode 200 with white emission can be achieved by mixing different colors.
According to another embodiment of the invention, the connecting electrode structure 240 can further comprise a metal layer 246 formed between the layer containing an alkali or alkaline earth compound 242 and the metal oxide layer or semiconductor layer 244, referring to
The following examples are intended to illustrate the invention more fully without limiting their scope, since numerous modifications and variations will be apparent to those skilled in this art.
A glass substrate with an indium tin oxide (ITO) film of 100 nm in thickness was provided and then washed by a cleaning agent, acetone, and isopropanol with ultrasonic agitation. After drying with nitrogen flow, the ITO film was subjected to uv/ozone treatment. Next, a hole injection layer, hole transport layer, light-emitting layer (with electron transport characteristic), electron injection layer, and aluminum electrode were subsequently formed on the ITO film at 10−5 Pa, obtaining the electroluminescent device (1). For purposes of clarity, the materials and layers formed therefrom are described in the following.
The hole injection layer, with a thickness of 20 nm, consisted of PEDT/PSS(Poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate)aqueous dispersion). The hole transport layer, with a thickness of 40 nm, consisted of NPB (N,N′-di-1-naphthyl-N,N′-diphenyl-1,1′-biphenyl-1,1′-biphenyl-4,4′-diamine). The light-emitting layer (with electron transport characteristic), with a thickness of 60 nm, consisted of Alq3 (tris (8-hydroxyquinoline)aluminum, yellowgreen emission (λmax=540 nm)). The electron injection layer, with a thickness of 1 nm, consisted of Cs2CO3. The aluminum electrode had a thickness of 100 nm.
The optical property of electroluminescent device (1), as described in Comparative Example 1, was measured by PR650 (purchased from Photo Research Inc.) and Minolta LS110.
A glass substrate with an indium tin oxide (ITO) film of 100 nm was provided and then washed by a cleaning agent, acetone, and isopropanol with ultrasonic agitation. After drying with nitrogen flows the ITO film was subjected to uv/ozone treatment. Next, a hole injection layer, first hole transport layer, first light-emitting layer (with electron transport characteristic), connecting electrode structure, second hole transport layer, second light-emitting layer (with electron transport characteristic), electron injection layer, and aluminum electrode were subsequently formed on the ITO film at 10−5 Pa, obtaining the electroluminescent device (2). For purposes of clarity, the materials and layers formed therefrom are described in the following.
The hole injection layer, with a thickness of 20 nm, consisted of PEDT/PSS (Poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate)aqueous dispersion). The first hole transport layer, with a thickness of 40 nm, consisted of NPB (N,N′-di-1-naphthyl-N,N′-diphenyl-1,1′-biphenyl-1,1′-biphenyl-4,4′-diamine). The first light-emitting layer (with electron transport characteristic), with a thickness of 40 nm, consisted of Alq3. The connecting electrode structure sequentially comprises the layer containing alkali or alkaline earth compounds, the metal layer and the metal oxide layer. The layer containing alkali or alkaline earth compounds, with a thickness of 20 nm, consisted of Alq3 as host, and Cs2CO3 as dopant, wherein the weight ratio between Cs2CO3 and Alq3 was 1:4. The metal layer, with a thickness of 5 nm, consisted of Al. The metal oxide layer, with a thickness of 5 nm, consisted of MoO3. The second hole transport layer, with a thickness of 40 nm, consisted of NPB (N,N′-di-1-naphthyl-N,N′-diphenyl-1,1′-biphenyl-1,1′-biphenyl-4,4′-diamine). The second light-emitting layer (with electron transport characteristic), with a thickness of 60 nm, consisted of Alq3. The electron injection layer, with a thickness of 1 nm, consisted of Cs2CO3. The aluminum electrode has a thickness of 100 nm.
The optical property of electroluminescent device (2), as described in Example 1, was measured by PR650 (purchased from Photo Research Inc.) and Minolta LS110.
Example 2 (electroluminescent device (3)) was performed the same as Example 1 except that the thickness of the metal layer was reduced to 1 nm. Example 3 (electroluminescent device (4)) was performed the same as Example 2 except that Ag was substituted for Al, to serve as the material of the metal layer. Example 4 (electroluminescent device (5)) was performed the same as Example 1 except for the removal of the metal layer.
Brightness (measured at 20 mA/cm2): electroluminescent devices (2˜4) (3000 cd/m2)>electroluminescent device (5) (1200 cd/m2)>electroluminescent device (1) (700 cd/m2)
Efficiency (measured at 20 mA/cm2): electroluminescent devices (2 and 4) (8.3 cd/A)>electroluminescent device (3) (˜8 cd/A)>electroluminescent device (5) (5.8 cd/A)>electroluminescent device (1) (3.8 cd/A).
A glass substrate with an indium tin oxide (ITO) film of 100 nm was provided and then washed by a cleaning agent, acetone, and isopropanol with ultrasonic agitation. After drying with nitrogen flow, the ITO film was subjected to uv/ozone treatment. Next, a hole injection layer, hole transport layer, blue light-emitting layer, red light-emitting layer, electron transport layer, electron injection layer, and aluminum electrode were subsequently formed on the ITO film at 10−5 Pa, obtaining the electroluminescent device (6). For purposes of clarity, the materials and layers formed therefrom are described in the following.
The hole injection layer, with a thickness of 60 nm, consisted of HI-406 (derivatives of triphenylamine, manufactured and sold by Idemitsu Co., Ltd.). The hole transport layer, with a thickness of 20 nm, consisted of HT-302 (derivatives of triphenylamine, manufactured and sold by Idemitsu Co., Ltd.). The blue light-emitting layer, with a thickness of 10 nm, consisted of BD-04(derivatives of anthence, manufactured and sold by Idemitsu Co., Ltd.) as dopant, and BH-01 (derivatives of anthence, manufactured and sold by Idemitsu Co., Ltd.) as light-emitting material host, wherein the weight ratio between BD-04 and BH-01 was 2.5:97.5. The red light-emitting layer, with a thickness of 25 nm, consisted of RD-01 (derivatives of anthence, manufactured and sold by Idemitsu Co., Ltd.) as dopant, and BH-01 as light-emitting material host, wherein the weight ratio between RD-01 and BH-01 was 2.68:97.32. The electron transport layer, with a thickness of 10 nm, consisted of Alq3 (tris (8-hydroxyquinoline)aluminum). The electron injection layer, with a thickness of 0.7 nm, consisted of LiF). The aluminum electrode has a thickness of 100 nm.
The optical property of electroluminescent device (6), as described in Comparative Example 2, was measured by PR650 (purchased from Photo Research Inc.) and Minolta LS110.
A glass substrate with an indium tin oxide (ITO) film of 100 nm was provided and then washed by a cleaning agent, acetone, and isopropanol with ultrasonic agitation. After drying with nitrogen flow, the ITO film was subjected to uv/ozone treatment. Next, a first hole injection layer, first hole transport layer, first blue light-emitting layer, first red light-emitting layer, first electron transport layer, connecting electrode structure, second hole injection layer, second hole transport layer, second blue light-emitting layer, second red light-emitting layer, second electron transport layer, electron injection layer, and aluminum electrode were subsequently formed on the ITO film at 10−5 Pa, obtaining the electroluminescent device (7). For purposes of clarity, the materials and layers formed therefrom are described in the following.
The first hole injection layer, with a thickness of 60 nm, consisted of HI-406. The first hole transport layer, with a thickness of 20 nm, consisted of HT-302. The first blue light-emitting layer, with a thickness of 10 nm, consisted of BD-04 as dopant, and BH-01 as light-emitting material host, wherein the weight ratio between BD-04 and BH-01 was 2.5:97.5. The first red light-emitting layer, with a thickness of 25 nm, consisted of RD-01 as dopant, and BH-01 as light-emitting material host, wherein the weight ratio between RD-01 and BH-01 was 2.68:97.32. The first electron transport layer, with a thickness of 10 nm, consisted of Alq3. The connecting electrode structure sequentially comprises the layer containing alkali or alkaline earth compounds, the metal layer and the metal oxide layer. The layer containing alkali or alkaline earth compounds, with a thickness of 20 nm, consisted of Alq3 as host, and Cs2CO3 as dopant, wherein the weight ratio between Cs2CO3 and Alq3 was 1:4 electron transport layer. The metal layer, with a thickness of 1 nm, consisted of Al. The metal oxide layer, with a thickness of 5 nm, consisted of MoO3. The second hole injection layer, with a thickness of 50 nm, consisted of HI-406. The second hole transport layer, with a thickness of 20 nm, consisted of HT-302. The second blue light-emitting layer, with a thickness of 10 nm, consisted of BD-04 as dopant, and BH-01 as light-emitting material host, wherein the weight ratio between BD-04 and BH-01 was 2.5:97.5. The second red light-emitting layer, with a thickness of 25 nm, consisted of RD-01 as dopant, and BH-01 as light-emitting material host, wherein the weight ratio between RD-01 and BH-01 was 2.68:97.32. The second layer, with a thickness of 25 nm, consisted of Alq3. The electron injection layer, with a thickness of 1 nm, consisted of Cs2CO3. The aluminum electrode has a thickness of 100 nm.
The optical property of electroluminescent device (7), as described in Example 5, was measured by PR650 (purchased from Photo Research Inc.) and Minolta LS110.
Examples 6 and 7 (electroluminescent devices (8˜9)) performed as Example 5except that the thickness of the second hole injection layer were increased to 55 nm and 60 nm respectively.
Brightness (measured at 20 mA/cm2): electroluminescent devices (7˜9) (3600 cd/m2)>electroluminescent device (6) (1500 cd/m2)
Efficiency (measured at 20 mA/cm2): electroluminescent device (9) (17.5 cd/A)>electroluminescent device (7) (16.9 cd/A)>electroluminescent device (8) (16.6 cd/A)>electroluminescent device (6) (8.3 cd/A)
Further, referring to
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
