基于CBP的有机电致磷光器件发光机理研究
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摘要
白色有机电致发光器件(WOLED)不但可以应用于平板显示器领域中,实现低功耗和全彩显示,而且还可以应用于其他固态照明领域,广泛的应用前景引起了人们极大的兴趣。本论文回顾了OLED器件的发展史、相关的理论基础和器件物理,之后主要研究了发光材料的激子寿命:
通过一维激子扩散模型模拟了不同厚度的四种有机薄膜时间分辨发光衰减曲线,有机物薄膜结构分别为: CBP/LiF/Al; CBP:FirPic(5%/8%的掺杂质量比)/LiF/Al; CBP:Ir(piq)2(acac) (5%/8%的掺杂质量比) /LiF/Al; CBP:Ir(ppy)3(5%/8%的掺杂质量比) / LiF/Al。
通过时间分辨发光衰减曲线,得到各结构的激子寿命τ,再由MATLAB程序模拟得出D、x0、LD,以上各结构的淬灭区域宽度为:8.3nm,41.6nm,41.9nm,42.4nm。制备上述CBP掺杂体系器件时,发光层的厚度应大约在100nm左右。同时还得到不同掺杂比时参数D、x0不变,τ、LD及淬灭区域宽度均不同,其中LD变化不超过5nm。
用磷光材料Ir(piq)2(acac)、Ir(ppy)3、Firpic和小分子主体材料CBP做发光层,制成了三种不同结构的白光器件: a,ITO/CBP:Firpic:Ir(piq)2(acac) /BCP /Alq3 /LiF / Al; b,ITO/CBP:Ir(piq)2(acac)(掺杂质量比8%)/BCP(Xnm)/ CBP:Firpic (掺杂质量比8%)/BCP/ Alq3 /LiF / Al; c , ITO/CBP : Ir(ppy)3 : Ir(piq)2(acac) /BCP(6埃)/ CBP:Firpic (掺杂质量比8%)/PBD/LiF/Al。
通过研究器件的电致发光光谱、色坐标、显色指数,得到a结构中CBP:Firpic:Ir(piq)2(acac掺杂比为200:200:10时器件效果最好;b结构中BCP隔层厚度为29埃时,器件效果最好;c结构中CBP:Ir(ppy)3 :Ir(piq)2(acac)的掺杂比为100:8:2时器件效果最好,而且实现了结构较简单的近标准白光发射。
White organic light-emitting device (WOLED) not only can be used in the field of flat panel displays, carried out low power consumption and full-color display, but also can be applied to other solid-state lighting, extensive application prospect has aroused great interest. This paper reviews the developmental history of OLED devices, the relevant oretical basis and device physics, followed by major researching the exciton lifetime of light-emitting materials, in order to supply the theoretical basis with optimizing the device structures to get the standard near-white emission. Specific results are as follows:
we simulate the time-resolved luminescence decay curves of different thickness of four kinds of organic thin-film, through the model of one-dimensional exciton diffusion, three kinds of organic thin-film structures are: CBP/LiF/Al; CBP:FirPic(5%/8% mass ratio of doping)/LiF/Al; CBP:Ir(piq)2(acac) (5%/8% mass ratio of doping) /LiF/Al; CBP:Ir(ppy)3(5%/8% mass ratio of doping) / LiF/Al .
By time-resolved luminescence decay curves, we obtaine the exciton lifetimeτof every structure, then through simulating the MATLAB program ,we get D、x0、LD and the above structure’s quenching area width is: 8.3nm,41.6nm,41.9nm,42.4nm. When we prepare the doped CBP device, the thickness of light-emitting layer is about 100nm. D、x0 is same for different doped ratios,τ、LD and quenching area width are different, which the variable of LD is no more than 5nm.
Using phosphorescent material Ir(piq)2(acac), Ir(ppy)3, Firpic and small molecu- le host material-CBP as the light-emitting layer, prepared three different structures of the white device: a,ITO/CBP:Firpic:Ir(piq)2(acac) /BCP /Alq3 /LiF / Al; b,ITO/CBP:Ir(piq)2(acac) (8% mass ratio of doping)/BCP(Xnm)/ CBP:Firpic(8% mass ratio of doping)/BCP/ Alq3 /LiF / Al; c,CBP:Ir(ppy)3:Ir(piq)2(acac) /BCP(6埃)/ CBP:Firpic(8% mass ratio of doping)/PBD/LiF/Al。
We study the electroluminescence spectra of the device, the color coordinates, the color rendering index, when the doped ratio of CBP: Fir (pic): Ir (piq)2(acac) is 200:200:10 ,the effect of structure-a is best; when the interlayered thickness is 29 angstrom,the effect of structure-b is best; when the doped ratio of CBP: Ir (ppy)3: Ir(piq)2(acac) is 100:8:2, the effect of structure-b is best, also achieved the standard white light-emission ,and structure is relatively simple.
通过一维激子扩散模型模拟了不同厚度的四种有机薄膜时间分辨发光衰减曲线,有机物薄膜结构分别为: CBP/LiF/Al; CBP:FirPic(5%/8%的掺杂质量比)/LiF/Al; CBP:Ir(piq)2(acac) (5%/8%的掺杂质量比) /LiF/Al; CBP:Ir(ppy)3(5%/8%的掺杂质量比) / LiF/Al。
通过时间分辨发光衰减曲线,得到各结构的激子寿命τ,再由MATLAB程序模拟得出D、x0、LD,以上各结构的淬灭区域宽度为:8.3nm,41.6nm,41.9nm,42.4nm。制备上述CBP掺杂体系器件时,发光层的厚度应大约在100nm左右。同时还得到不同掺杂比时参数D、x0不变,τ、LD及淬灭区域宽度均不同,其中LD变化不超过5nm。
用磷光材料Ir(piq)2(acac)、Ir(ppy)3、Firpic和小分子主体材料CBP做发光层,制成了三种不同结构的白光器件: a,ITO/CBP:Firpic:Ir(piq)2(acac) /BCP /Alq3 /LiF / Al; b,ITO/CBP:Ir(piq)2(acac)(掺杂质量比8%)/BCP(Xnm)/ CBP:Firpic (掺杂质量比8%)/BCP/ Alq3 /LiF / Al; c , ITO/CBP : Ir(ppy)3 : Ir(piq)2(acac) /BCP(6埃)/ CBP:Firpic (掺杂质量比8%)/PBD/LiF/Al。
通过研究器件的电致发光光谱、色坐标、显色指数,得到a结构中CBP:Firpic:Ir(piq)2(acac掺杂比为200:200:10时器件效果最好;b结构中BCP隔层厚度为29埃时,器件效果最好;c结构中CBP:Ir(ppy)3 :Ir(piq)2(acac)的掺杂比为100:8:2时器件效果最好,而且实现了结构较简单的近标准白光发射。
White organic light-emitting device (WOLED) not only can be used in the field of flat panel displays, carried out low power consumption and full-color display, but also can be applied to other solid-state lighting, extensive application prospect has aroused great interest. This paper reviews the developmental history of OLED devices, the relevant oretical basis and device physics, followed by major researching the exciton lifetime of light-emitting materials, in order to supply the theoretical basis with optimizing the device structures to get the standard near-white emission. Specific results are as follows:
we simulate the time-resolved luminescence decay curves of different thickness of four kinds of organic thin-film, through the model of one-dimensional exciton diffusion, three kinds of organic thin-film structures are: CBP/LiF/Al; CBP:FirPic(5%/8% mass ratio of doping)/LiF/Al; CBP:Ir(piq)2(acac) (5%/8% mass ratio of doping) /LiF/Al; CBP:Ir(ppy)3(5%/8% mass ratio of doping) / LiF/Al .
By time-resolved luminescence decay curves, we obtaine the exciton lifetimeτof every structure, then through simulating the MATLAB program ,we get D、x0、LD and the above structure’s quenching area width is: 8.3nm,41.6nm,41.9nm,42.4nm. When we prepare the doped CBP device, the thickness of light-emitting layer is about 100nm. D、x0 is same for different doped ratios,τ、LD and quenching area width are different, which the variable of LD is no more than 5nm.
Using phosphorescent material Ir(piq)2(acac), Ir(ppy)3, Firpic and small molecu- le host material-CBP as the light-emitting layer, prepared three different structures of the white device: a,ITO/CBP:Firpic:Ir(piq)2(acac) /BCP /Alq3 /LiF / Al; b,ITO/CBP:Ir(piq)2(acac) (8% mass ratio of doping)/BCP(Xnm)/ CBP:Firpic(8% mass ratio of doping)/BCP/ Alq3 /LiF / Al; c,CBP:Ir(ppy)3:Ir(piq)2(acac) /BCP(6埃)/ CBP:Firpic(8% mass ratio of doping)/PBD/LiF/Al。
We study the electroluminescence spectra of the device, the color coordinates, the color rendering index, when the doped ratio of CBP: Fir (pic): Ir (piq)2(acac) is 200:200:10 ,the effect of structure-a is best; when the interlayered thickness is 29 angstrom,the effect of structure-b is best; when the doped ratio of CBP: Ir (ppy)3: Ir(piq)2(acac) is 100:8:2, the effect of structure-b is best, also achieved the standard white light-emission ,and structure is relatively simple.
引文
[1] DESTRIAU G. Recherches sur les scintillation de zinc auxrayons. [J]. Chem. Phys., 1936, 33 :5872594.
[2] POPE M, KALLMANN H P, MAGNANTE P. Electroluminescence in organic crystals [J ] .Chem. Phys., 1963 , 38 :2042-2043.
[3] VINCETT P S, BARLOW W A, HANM R A, et al. Electrical conduction and low voltage blue electroluminescence in vacuum deposited organic films. [J ] . Thin SolidFilms, 1982, 94:1712174.
[4] Pope M, Kallmann H P, Mangnante P., Electroluminescence in Organic Crystals. [J]. Chem. Phy.s, 1963, 38(8):2042
[5] Dresne J.Double injection electroluminescence in anthravene. [J]. RCA Rev. ,1969, 30:322-334.
[6] Vincett P S, Barloow W A, Hann R A, Robert G G. Thin solid Films, 1982,94:171.
[7] C .W. Tang, S. A. Vanslyke. Organic Electroluminescent Diodes. [J].Appl.Phys.Lett.,1987, 51:913-915.
[8] Burroughes J H, Bradley D D C, Brown A R, Marks R N. Light-emitting Diodes Based on Conjugated Polymer. [J]. Nature, 1990, 347:539
[9] Gustufsson G, Cao Y, Treacy G. M., Flexible Light Emitting Diodes Made from Soluble Conducting Polymers. [J] Nature, 1992, 357:477
[10] Cao Y, Treacy G M, Smith P, Heeger A., Solution-cast Films of Polyaniline:Optical-quality Transparent Electrodes. [J]. Appl. Phys. Lett., 1992,60:2711
[11] Huang Y S, Jou J H, KuoW, et al. High-efficiency white organic light-emitting devices with dual doped structure. [ J ].Appl. Phys. Lett. , 2002, 80 (15) : 2782-2784.
[12] Sun Yuanyuan, Hua Yulin, Xu Feng, et al. Fabrication and study of flexible organic light emitting devices. [ J ]. J. Opto-electronics·Laser (光电子·激光) , 2005, 16 (9) : 1021-1024 ( in Chinese).
[13] Suzuki H, Hoshino S. Effects of doping dyes on the electroluminescent characteristics of multip layer organic light-emitting diodes. [J]. Jpn. J. Appl. Phys. , 1996, 79 (11) : 8816-8822.[14] Gao Z Q, Lee C S, Bello I, et al. White light electroluminescence from a hole2transporting layer of mixed organic materials. [ J ]. Synth. Met. , 2000, 1112112: 39-42.
[15] Yu Junsheng, Li Weizhi, Jiang Yadong, et al. Bright yellow organic electroluminescent devices using a novel silole derivative as emitter. [ J ]. Jpn. J. Appl. Phys. , 2007, 46 (2) : L31-L33.
[16] Yu Junsheng, Chen Zhijian, Sone M, et al. Red light-emitting organic electroluminescent devices with bisanil dye as emitter. [ J ]. Jpn. J. Appl. Phys. (A) , 2001, 40 (5A) : 3201-3205.
[17] Shi Yumeng, Deng Zhenbo, Xu Denghui, et al. The luminance efficiency imp rovement of organic light-emitting diodes usingmultip le-quantum-well structure. [J]. J.Optoelectronics·Laser (光电子·激光) , 2007, 18 ( 2 ) : 171-174 ( in Chinese).
[18] Niu Xia, Hua Yulin, Wu Kongwu, et al. Characteristics of a double layerswhite organic electroluminescent device using TBPe as dopant in a blue mixed layer. [J]. Chin. J. Lum in. (发光学报) , 2006, 27 (4) : 5372542 ( in Chinese).
[19] Wang Xiuru, Wu Youzhi, Chen Haoyu, et al. Dual colorOLEDs using a novel Ir comp lex. [J]. Chin. J. Lum in. (发光学报) , 2006, 27 (5) : 695-699 ( in Chinese).
[20] Yan L ingling, L i Hongjian, Zhang J ianhuan, et al. Electroluminescence spectra in microcavity organic light-emitting devices. [J]. Chin. J. Lum in. (发光学报) , 2007, 28 (2) : 173-178 ( in Chinese).
[21] S. A. Van Slyke, C. H. Chen, and C. W. Tang, Organic electroluminescent devices with improved stability. Appl. Phys. Lett., 1996, 69, 2160-2162.
[22] C. Adachi, S. Tokito, T. Tsutsui and S. Saito, Organic electroluminescent devices with a three-layer structures. Jap. J. Appl. Phys., 1988, 27, 713-715.
[23] A. Loannidis, E. Forsythe, Y. Gao, M. W. Wu, and E. M. Conwell, Current-voltage characteristic of organic light emitting diodes. Appl. Phys. Lett., 1998, 72,3038-3040.
[24] G. Giebeter, H. Antoniadis, D. D. C. Bradley, and Y. Shirota, Space-charge-limited charge injection from indium tin oxide into a starburst amine and its implications for organic light- emitting diodes. Appl. Phys. Lett., 1998, 72, 2448-2450.
[25] C. Hosokawa, N. Kawasaki, S. Sakamoto, and T. kusumoto, Bright blue electroluminescence from hole transporting polyacrbonate. Appl. Phys. Lett., 1992, 61, 2503-2505.
[26] S. R. Forrest, P. E. Burrows, Z. Shen, et al.The stacked OLED (SOLED): a new type of organic device for achieving high-resolution full-color displays. Synth. Metal, 1997, 91, 9-13.
[27] A. Rajagopal, and A. Kahn. Photoemission spectroscopy investigation of magnesium-Alq3 interfaces, Appl. Phys. Lett., 1998, 84, 355-357.
[28] H. Ishhii, K. Sugiyama, E. Ito, et al. Energy Level Alignment and Interfacial Electronic structures atOrganic/Metal and Organic/Organic Interfaces. Adv. Mater., 1999, 11, 605-625.
[29] S. T. Lee, Y. M. Wang, X. Y. Hou, and C. W. Tang, Interfacial electronic structures in an organic light-emitting diode. Appl. Phys. Lett., 1999, 74, 670-672.
[30] M. Matsumura and Y. Jinda, Analysis of current-voltage characteristics of organic light emitting diodes having a LiF/Al cathode and an Al-hydroxyquinoline/diamine junction. Appl. Phys. Lett., 1998, 73, 2872-2874.
[31] A. Kraft, et al., electroluminescent conjugated polymers—seeing polymers in a new light. Angew. Chem. Int. Ed., 1998, 37, 402.
[32] M. T. Bernius, et al., Progress with Light-Emitting Polymers. Adv. Mater., 2000, 12,1737.
[33]黄春辉,李富友,黄维,有机电之发光材料与器件导论,复旦大学出版社,2005,p111
[34]吴晓明,华玉林印寿根,等.不同主体双发光层白色有机电致发光器件的性能研究[J]物理学报,2008,57(2):1150-1154.
[35] D. E. Markova, P. W. M. Blom. Exciton quenching in poly(phenylene vinylene) polymer light- emitting diodes, Appl. Phys. Lett., 2005,87, 233511-2.
[36] Xie Z Y, Hung L S, Lee S T. High-efficiency red electroluminescence from a narrow recombination zone confined by an organic double heterostructure. [ J ]. Appl. Phys. Lett. , 2001, 79 (7) : 1048-1050.
[37] Lee S S, Song T J , Cho SM. Organic white2light2emitting devices based on balanced exciton recombination zone split using a carrier blocking layer. [ J ]. M ater. Sci. & Eng. B,2002, 95 (1) : 24-28.
[38] Kido J , KimuraM, Nagai K. Multilayerwhite light2emitting organic electroluminesecnt device. [ J ]. Science, 1995, 267(5202) : 1332-1334.
[2] POPE M, KALLMANN H P, MAGNANTE P. Electroluminescence in organic crystals [J ] .Chem. Phys., 1963 , 38 :2042-2043.
[3] VINCETT P S, BARLOW W A, HANM R A, et al. Electrical conduction and low voltage blue electroluminescence in vacuum deposited organic films. [J ] . Thin SolidFilms, 1982, 94:1712174.
[4] Pope M, Kallmann H P, Mangnante P., Electroluminescence in Organic Crystals. [J]. Chem. Phy.s, 1963, 38(8):2042
[5] Dresne J.Double injection electroluminescence in anthravene. [J]. RCA Rev. ,1969, 30:322-334.
[6] Vincett P S, Barloow W A, Hann R A, Robert G G. Thin solid Films, 1982,94:171.
[7] C .W. Tang, S. A. Vanslyke. Organic Electroluminescent Diodes. [J].Appl.Phys.Lett.,1987, 51:913-915.
[8] Burroughes J H, Bradley D D C, Brown A R, Marks R N. Light-emitting Diodes Based on Conjugated Polymer. [J]. Nature, 1990, 347:539
[9] Gustufsson G, Cao Y, Treacy G. M., Flexible Light Emitting Diodes Made from Soluble Conducting Polymers. [J] Nature, 1992, 357:477
[10] Cao Y, Treacy G M, Smith P, Heeger A., Solution-cast Films of Polyaniline:Optical-quality Transparent Electrodes. [J]. Appl. Phys. Lett., 1992,60:2711
[11] Huang Y S, Jou J H, KuoW, et al. High-efficiency white organic light-emitting devices with dual doped structure. [ J ].Appl. Phys. Lett. , 2002, 80 (15) : 2782-2784.
[12] Sun Yuanyuan, Hua Yulin, Xu Feng, et al. Fabrication and study of flexible organic light emitting devices. [ J ]. J. Opto-electronics·Laser (光电子·激光) , 2005, 16 (9) : 1021-1024 ( in Chinese).
[13] Suzuki H, Hoshino S. Effects of doping dyes on the electroluminescent characteristics of multip layer organic light-emitting diodes. [J]. Jpn. J. Appl. Phys. , 1996, 79 (11) : 8816-8822.[14] Gao Z Q, Lee C S, Bello I, et al. White light electroluminescence from a hole2transporting layer of mixed organic materials. [ J ]. Synth. Met. , 2000, 1112112: 39-42.
[15] Yu Junsheng, Li Weizhi, Jiang Yadong, et al. Bright yellow organic electroluminescent devices using a novel silole derivative as emitter. [ J ]. Jpn. J. Appl. Phys. , 2007, 46 (2) : L31-L33.
[16] Yu Junsheng, Chen Zhijian, Sone M, et al. Red light-emitting organic electroluminescent devices with bisanil dye as emitter. [ J ]. Jpn. J. Appl. Phys. (A) , 2001, 40 (5A) : 3201-3205.
[17] Shi Yumeng, Deng Zhenbo, Xu Denghui, et al. The luminance efficiency imp rovement of organic light-emitting diodes usingmultip le-quantum-well structure. [J]. J.Optoelectronics·Laser (光电子·激光) , 2007, 18 ( 2 ) : 171-174 ( in Chinese).
[18] Niu Xia, Hua Yulin, Wu Kongwu, et al. Characteristics of a double layerswhite organic electroluminescent device using TBPe as dopant in a blue mixed layer. [J]. Chin. J. Lum in. (发光学报) , 2006, 27 (4) : 5372542 ( in Chinese).
[19] Wang Xiuru, Wu Youzhi, Chen Haoyu, et al. Dual colorOLEDs using a novel Ir comp lex. [J]. Chin. J. Lum in. (发光学报) , 2006, 27 (5) : 695-699 ( in Chinese).
[20] Yan L ingling, L i Hongjian, Zhang J ianhuan, et al. Electroluminescence spectra in microcavity organic light-emitting devices. [J]. Chin. J. Lum in. (发光学报) , 2007, 28 (2) : 173-178 ( in Chinese).
[21] S. A. Van Slyke, C. H. Chen, and C. W. Tang, Organic electroluminescent devices with improved stability. Appl. Phys. Lett., 1996, 69, 2160-2162.
[22] C. Adachi, S. Tokito, T. Tsutsui and S. Saito, Organic electroluminescent devices with a three-layer structures. Jap. J. Appl. Phys., 1988, 27, 713-715.
[23] A. Loannidis, E. Forsythe, Y. Gao, M. W. Wu, and E. M. Conwell, Current-voltage characteristic of organic light emitting diodes. Appl. Phys. Lett., 1998, 72,3038-3040.
[24] G. Giebeter, H. Antoniadis, D. D. C. Bradley, and Y. Shirota, Space-charge-limited charge injection from indium tin oxide into a starburst amine and its implications for organic light- emitting diodes. Appl. Phys. Lett., 1998, 72, 2448-2450.
[25] C. Hosokawa, N. Kawasaki, S. Sakamoto, and T. kusumoto, Bright blue electroluminescence from hole transporting polyacrbonate. Appl. Phys. Lett., 1992, 61, 2503-2505.
[26] S. R. Forrest, P. E. Burrows, Z. Shen, et al.The stacked OLED (SOLED): a new type of organic device for achieving high-resolution full-color displays. Synth. Metal, 1997, 91, 9-13.
[27] A. Rajagopal, and A. Kahn. Photoemission spectroscopy investigation of magnesium-Alq3 interfaces, Appl. Phys. Lett., 1998, 84, 355-357.
[28] H. Ishhii, K. Sugiyama, E. Ito, et al. Energy Level Alignment and Interfacial Electronic structures atOrganic/Metal and Organic/Organic Interfaces. Adv. Mater., 1999, 11, 605-625.
[29] S. T. Lee, Y. M. Wang, X. Y. Hou, and C. W. Tang, Interfacial electronic structures in an organic light-emitting diode. Appl. Phys. Lett., 1999, 74, 670-672.
[30] M. Matsumura and Y. Jinda, Analysis of current-voltage characteristics of organic light emitting diodes having a LiF/Al cathode and an Al-hydroxyquinoline/diamine junction. Appl. Phys. Lett., 1998, 73, 2872-2874.
[31] A. Kraft, et al., electroluminescent conjugated polymers—seeing polymers in a new light. Angew. Chem. Int. Ed., 1998, 37, 402.
[32] M. T. Bernius, et al., Progress with Light-Emitting Polymers. Adv. Mater., 2000, 12,1737.
[33]黄春辉,李富友,黄维,有机电之发光材料与器件导论,复旦大学出版社,2005,p111
[34]吴晓明,华玉林印寿根,等.不同主体双发光层白色有机电致发光器件的性能研究[J]物理学报,2008,57(2):1150-1154.
[35] D. E. Markova, P. W. M. Blom. Exciton quenching in poly(phenylene vinylene) polymer light- emitting diodes, Appl. Phys. Lett., 2005,87, 233511-2.
[36] Xie Z Y, Hung L S, Lee S T. High-efficiency red electroluminescence from a narrow recombination zone confined by an organic double heterostructure. [ J ]. Appl. Phys. Lett. , 2001, 79 (7) : 1048-1050.
[37] Lee S S, Song T J , Cho SM. Organic white2light2emitting devices based on balanced exciton recombination zone split using a carrier blocking layer. [ J ]. M ater. Sci. & Eng. B,2002, 95 (1) : 24-28.
[38] Kido J , KimuraM, Nagai K. Multilayerwhite light2emitting organic electroluminesecnt device. [ J ]. Science, 1995, 267(5202) : 1332-1334.