磷光配合物Ir（ppy）_3掺杂PVK体系发光特性研究
摘要
本文对常温下磷光染料三(2-苯基吡啶)铱[Ir(ppy)3]掺杂高分子材料聚乙烯基咔唑PVK薄膜的光致发光(PL)和电致发光(EL)特性进行了研究,器件结构为ITO/PEDOT: PSS/EML/BCP/Alq3/Al.实验发现通过磷光材料掺杂浓度的变化,器件的发光性能发生变化。在直流电压下,当浓度适宜时,主体材料PVK的发光很弱,主要为Ir(ppy)3的磷光发射；通过L-I-V特性曲线的比较,掺杂浓度为5%的器件的光电性能最好,说明器件在掺杂浓度为5%时效果最佳。改变器件的结构为ITO/NPB/EML/BCP/Alq3/Al,在直流电压驱动下,器件发光性能得到提高；在交流电压驱动下,器件的发光强度为随频率的变化而变化,当频率为1000Hz时,发光强度最高。在荧光材料中掺杂合适的磷光敏化剂,可以大大提高荧光材料的发光效率。用磷光材料Ir(ppy)3分别与荧光材料DCJTB、Rubrene掺杂,对磷光材料的敏化作用进行了分析,并比较了Ir(ppy)3对两种不同荧光材料的敏化作用强弱,认为Ir(ppy)3对荧光材料Rubrene的敏化作用更强。同时,当掺杂质量比合适时,磷光材料的发光消失,得到了纯正的荧光材料的发光。
In this paper, the photoluminescent and electroluminescent spectra of Phosphorescence material Ir(ppy)3 doped polymer material PVK film were measured at room temperature. The structure of devices is ITO/PEDOT:PSS/EML/BCP/Alq3/Al. The results show that the luminescent capabilities of devices are alter when the concentration of Ir(ppy)3 is changed. When the concentration of Ir(ppy)3 is suitable, the luminescence of PVK is lower but that of Ir(ppy)3 stronger relatively, which shows that the energy transfer from the host materials to the guest materials is sufficient. It is concluded that the device with 5% of Ir(ppy)3 has the best luminescence properties according to its light power-current-voltage curve. It means that the best concentration of Ir(ppy)3 in such kind of device is 5%. Change the device structure to ITO/NPB/EML/BCP/Alq3/Al, the luminescent capabilities are improved under DC drive; the luminescent intensity changes by the frequency under AC drive, and has a maximum at 1000 Hz. The luminescent efficiency of fluorescence material can be greatly improved when phosphorescent material as a sensitizer is doped in with suitable concentration. Doping Phosphorescence material Ir(ppy)3 into fluorescence material DCJTB and Rubrene separately, we analysed the sensitizing effect of Phosphorescence material. We found that Rubrene was better sensitized by comparing the two fluorescence materials. At the same time, we couldn't see the luminescence of Phosphorescence material and got pure luminescence of fluroscence material when the concentration si suitable.
In this paper, the photoluminescent and electroluminescent spectra of Phosphorescence material Ir(ppy)3 doped polymer material PVK film were measured at room temperature. The structure of devices is ITO/PEDOT:PSS/EML/BCP/Alq3/Al. The results show that the luminescent capabilities of devices are alter when the concentration of Ir(ppy)3 is changed. When the concentration of Ir(ppy)3 is suitable, the luminescence of PVK is lower but that of Ir(ppy)3 stronger relatively, which shows that the energy transfer from the host materials to the guest materials is sufficient. It is concluded that the device with 5% of Ir(ppy)3 has the best luminescence properties according to its light power-current-voltage curve. It means that the best concentration of Ir(ppy)3 in such kind of device is 5%. Change the device structure to ITO/NPB/EML/BCP/Alq3/Al, the luminescent capabilities are improved under DC drive; the luminescent intensity changes by the frequency under AC drive, and has a maximum at 1000 Hz. The luminescent efficiency of fluorescence material can be greatly improved when phosphorescent material as a sensitizer is doped in with suitable concentration. Doping Phosphorescence material Ir(ppy)3 into fluorescence material DCJTB and Rubrene separately, we analysed the sensitizing effect of Phosphorescence material. We found that Rubrene was better sensitized by comparing the two fluorescence materials. At the same time, we couldn't see the luminescence of Phosphorescence material and got pure luminescence of fluroscence material when the concentration si suitable.
引文
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[14]C. Adachi, M. A. Baldo, M. E. Thompson, et al. Nearly 100% internal phosphorescence efficiency in an organic light-emitting device[J]. J. Appl. phys.2001,90(10):5048-5051
[15]L. S. Liao, K.P. Klubek, C. W. Tang, et al. High-efficiency Tandem Organic Light-emitting Diodes [J]. Appl. Phys. Lett.2004,84:167-169
[16]S. R. Forrest, The Path to Ubiquitous and Low-cost Organic Electronicappliances on Plastic [J]. Nature,2005,428:911-918
[17]I. D. Parker. Carrier Tunneling and Device Characteristics in Polymer Light-emitting Diodes [J]. J. Appl Phys,1994,75:1656-1666
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[22]C. C. Wu, C. I. Wu, J. C. Strum, et. al. Surface Modification of Indium Tin Oxide by The Plasma Treatment:An Effective Method to Improve the Efficiency, Brightness, and Reliability of Organic Light Emitting Devices [J]. Appl. Phys. Lett.1997,70.1348-1350
[23]I. S. Hung, C. W. Tang, M. G Mason. Enhanced Electron Injection in Organic Electrolum-inescence Using an Al/LiF Electrode[J]. Appl.Phys.Lett.1997,70:152-154
[24]M. Stossel, J. Staudigel, F. Steuber, et. al. Space-charge-limited Electron Currents in 8-hydroxyquinoline Aluminum[J]. Appl. Phys. Lett.2000,76:115-117
[25]R. A. Keller, H. A. Rost, Tunneling Model for Electron Transport Temperature Dependence in Crystals of Low Carrier Mobility. Example:Anthracene[J]. J. Chem. Phys.1962,36:2640-2643
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[28]K. Pakbaz, C. H. Lee, A. J. Heeger, Ranking Fuzzy Values With Satisfaction Function[J]. Synth. Met.1994,64:295-298
[29]Z. Shuai, D. Beljonne, R. J. Silbey, et. al. Singlet and Triplet Exciton Formation Rates in Conjugated Polymer Light-emitting Diodes[J]. Phys. Rev. Lett.2000,84:131-134
[30]A. Ye, Z. Shuai, J. L. Bredas, Coupled-cluster Approach for Studying the Singlet and Triplet Exciton Formation Rates in Conjugated Polymer LEDs[J]. Phys. Rev. B,2002,65:045208-045221
[31]Y. Cao,I. D. Parker, G. Yu, et. al, Improved Quantum Efficiency for Electroluminescence in Semiconducting Polymers[J]. Nature,1999,397:414-417
[32]G.Z.Dai, H. J. Li, Y. Z. Pan, et.al. Energy transfer probability in organic electrophosphorescence device with dopant[J]. Chin. Phys. lett,2005,14(12):2590-2594
[33]黄春辉,李富友,黄维,有机电致发光材料与器件导论[M],上海：复旦大学出版社,2005,59
[34]王军,魏孝强,饶海波等.基于铱配合物材料的高效高稳定性有机发光二极管[J].Acta Phys.Sin(物理学报),2007,56(2)：1156-1161
[35]M. A. Baldo, M. E. Thompson, S. R. Forrest. High-efficiency fluorescent organic light-emitting devices using a phosphorescent sensitizer[J]. Nature,2000,403:750-753
[36]G. T. Lei, L. D. Wang, Y. Qiu. Blue phosphorescent dye as sensitizer and emitter for white organic light-emitting diodes[J]. Appl. Phys. Lett.2004,85(22):5403-5405
[37]G. Cheng, Y. F. Zhang, Y. Zhao, S. Y. Liu, et. al. Improved efficiency for white organic light-emitting devices based on phosphor sensitized fluorescence[J]. Appl. Phys. Lett.2006,88(8): 083512
[2]W. Helfrich, W. G Schneider. Recobination Radination in Anthracene Crystals [J]. Phys. Rew. Lett 1965,14,229-231
[3]D. F. Willians, M. Schadt, Light Emission from Single Crystal [J]. Proc. IEEE.1970,58:476-479
[4]P. S. Vincett, W. A. Barlow, R. A. Hann, et al. Electrical Conduction and Low Voltage Blue El-ectroluminescence in Vacuum Eposited Organic Films[J]. Thin Solid Film,1982,94:171-174
[5]C. W. Tang, S. A. Vanslyke, Organic Electroluminescent Diodes[J]. Appl. Phys. Lett.1987, 51:913-915
[6]C. W. Tang, S. A. Vanslyke, V. H. Chen, Electroluminescence of Doped Organic Thin Film s[J]. J. Appl. Phys,1989,65:3610-3616
[7]C. Adachi, S. Tokito, T.Tsutsui,et al. Organic Electroluminescent Device with a Three-layer Structure[J]. Jpn. J. Appl Phys, Part 1,1988,27:L713-L715
[8]J. H. Burroughes, D. D. C. Bradley, A. R. Brown, et al. Light-emitting Diodes Based on Conjugated Polymer[J]. Nature,1990,347:539-541
[9]D. Braun, A. J. Heeger, Visible Light Emission from Semiconducting Polymer Diodes [J]. Appl.Phys. Lett.1991,58:1982-1984
[10]G. Gustafasson, Y. Cao, A. J. Heeger, et al. Flexible Light-emitting Diodes Made from soluble conducting polymers[J]. Nature,1992,357:477-479
[11]Y. G. Ma, H. Y. Zhang, J. C. Shen. Electroluminescence from triplet metal-ligand charge-transfer excited state of transition metal complexes[J]. Synth. Met.,1998,94(3):245-248
[12]M. A. Baldo, D.F. O'Brien, Y.You, et al. Highly Efficient Phosphorescent Emission from Organic Electroluminescent Devices [J].Nature,1998,395:151-154
[13]M. A. Baldo, S. Lamasky, P. E. Burrows, et al. Very high-efficiency green organic light-emitting devices based on electrophosphorescence [J]. Appl. Phys. Lett.1999,75(1):4-6
[14]C. Adachi, M. A. Baldo, M. E. Thompson, et al. Nearly 100% internal phosphorescence efficiency in an organic light-emitting device[J]. J. Appl. phys.2001,90(10):5048-5051
[15]L. S. Liao, K.P. Klubek, C. W. Tang, et al. High-efficiency Tandem Organic Light-emitting Diodes [J]. Appl. Phys. Lett.2004,84:167-169
[16]S. R. Forrest, The Path to Ubiquitous and Low-cost Organic Electronicappliances on Plastic [J]. Nature,2005,428:911-918
[17]I. D. Parker. Carrier Tunneling and Device Characteristics in Polymer Light-emitting Diodes [J]. J. Appl Phys,1994,75:1656-1666
[18]R. H. Fowler, L. Nordheim, Electron Emission in Intense Electricfields [J]. Proc.Roy.Soc (London) 1928, Ser.A119,173-175
[19]E. H. Rhoderick, R. H. Williams. Metal-semiconductor Contacts [M]. xford:clarendon,1988
[20]H. Ishii, S. Hasegawa, D. Yoshimura, et. al. Electronic Structures of Porphyrins and Their Int-erfaces with Metals Studied by UV Photoemission [J]. Mol. Cryst.Liq. Cryst.1997,296:427-444
[21]D. M. Pai, Transient Photoconductivity in Poly(N-vinylcarbazole) [J].J.Chem. Phys.1970, 52:2285-2291
[22]C. C. Wu, C. I. Wu, J. C. Strum, et. al. Surface Modification of Indium Tin Oxide by The Plasma Treatment:An Effective Method to Improve the Efficiency, Brightness, and Reliability of Organic Light Emitting Devices [J]. Appl. Phys. Lett.1997,70.1348-1350
[23]I. S. Hung, C. W. Tang, M. G Mason. Enhanced Electron Injection in Organic Electrolum-inescence Using an Al/LiF Electrode[J]. Appl.Phys.Lett.1997,70:152-154
[24]M. Stossel, J. Staudigel, F. Steuber, et. al. Space-charge-limited Electron Currents in 8-hydroxyquinoline Aluminum[J]. Appl. Phys. Lett.2000,76:115-117
[25]R. A. Keller, H. A. Rost, Tunneling Model for Electron Transport Temperature Dependence in Crystals of Low Carrier Mobility. Example:Anthracene[J]. J. Chem. Phys.1962,36:2640-2643
[26]G. Kemeny, B. Rosenberg,Theory of the pre-exponential factor in organic semiconductors[J]. J. Chem. Phys.1970,52:4151-4153
[27]N. J. Turro, Modern Molecular Photochemistry[M].University Science Books, Mill Valley, California, USA,1991,18
[28]K. Pakbaz, C. H. Lee, A. J. Heeger, Ranking Fuzzy Values With Satisfaction Function[J]. Synth. Met.1994,64:295-298
[29]Z. Shuai, D. Beljonne, R. J. Silbey, et. al. Singlet and Triplet Exciton Formation Rates in Conjugated Polymer Light-emitting Diodes[J]. Phys. Rev. Lett.2000,84:131-134
[30]A. Ye, Z. Shuai, J. L. Bredas, Coupled-cluster Approach for Studying the Singlet and Triplet Exciton Formation Rates in Conjugated Polymer LEDs[J]. Phys. Rev. B,2002,65:045208-045221
[31]Y. Cao,I. D. Parker, G. Yu, et. al, Improved Quantum Efficiency for Electroluminescence in Semiconducting Polymers[J]. Nature,1999,397:414-417
[32]G.Z.Dai, H. J. Li, Y. Z. Pan, et.al. Energy transfer probability in organic electrophosphorescence device with dopant[J]. Chin. Phys. lett,2005,14(12):2590-2594
[33]黄春辉,李富友,黄维,有机电致发光材料与器件导论[M],上海：复旦大学出版社,2005,59
[34]王军,魏孝强,饶海波等.基于铱配合物材料的高效高稳定性有机发光二极管[J].Acta Phys.Sin(物理学报),2007,56(2)：1156-1161
[35]M. A. Baldo, M. E. Thompson, S. R. Forrest. High-efficiency fluorescent organic light-emitting devices using a phosphorescent sensitizer[J]. Nature,2000,403:750-753
[36]G. T. Lei, L. D. Wang, Y. Qiu. Blue phosphorescent dye as sensitizer and emitter for white organic light-emitting diodes[J]. Appl. Phys. Lett.2004,85(22):5403-5405
[37]G. Cheng, Y. F. Zhang, Y. Zhao, S. Y. Liu, et. al. Improved efficiency for white organic light-emitting devices based on phosphor sensitized fluorescence[J]. Appl. Phys. Lett.2006,88(8): 083512