聚合物放大自发辐射现象的研究
摘要
有机激光器存在着很多潜在的优点：加工制造工艺简单,制造成本较低,激光波长可调,可以在基片上实现大面积集成等。而有机半导体共轭聚合物由于具有较高的荧光效率,较大的受激发射截面,是一种很好激光器的增益介质,所以近年来,有机半导体共轭聚合物材料成为有机光电材料领域主要的研究方向之一。本论文主要研究了波导结构的有机共轭聚合物材料MEH-PPV的薄膜的放大辐射特性及其影响因素。
在实验中我们利用旋涂法制作了以甲苯为溶剂的MEH-PPV溶液的三层非对称波导结构的器件,在500 nm的激光泵浦的条件下观察到了MEH-PPV薄膜的受激发射。并且我们发现当泵浦光光强较低时,受激发射的光强也相对较低,谱线的半高宽也比较大,但是随着泵浦光光强的增强,发射光强出现较大的增长,显现出阈值的特性,并且发射谱线的半高宽也有明显的窄化。通过对比测量我们发现随着器件薄膜的厚度的增加器件的阈值有明显的下降,当薄膜厚度为93.3 nm时器件的阈值为0.219μJ/pluse,厚度增加至279.3 nm时,阈值下降至0.162μJ/pluse,而且此时器件的净增益达到28.2 cm-1。因为厚度的增加还有可能使泵浦能量快速耗尽,以及材料具有较高的衰减系数,所以器件薄膜的厚度也不能无限扩大。为了进一步认识厚度与受激发射的关系及规律,我们通过提高溶液的浓度和自然扩散法设计制作了560 nm和微米级别的器件进行研究。
最后对于不同的溶剂在相同的浓度下对波导结构的MEH-PPV薄膜器件的受激发射进行了研究。发现符合最适宜成膜的条件的氯苯溶剂所制作的器件的性能最佳,经过分析认为此器件的薄膜最为平整,通过原子力显微镜也证明此溶剂制作的波导的粗糙度最小。
The organic laser has many potential advantages:easy fabrication, low costs, tunable emission wavelength, large-scale integration. In recent years, conjugated organic semiconductor polymers have been one of the main research directions in organic optoelectronic materials due to their high fluorescence efficiency, large excitation cross section. In this paper, we discuss the amplified spontaneous emission (ASE) characteristics in MEH-PPV film and factors to influence ASE.
Under the pump of 500nm pulse laser, ASE of the MEH-PPV waveguide with asymmetric structures was investigated. We found that the output intensity is lower and the full width at half maximum (FWHM) is wider when the pump intensity is lower. However, with the increasing pump intensity, the quick increase in output intensity y and the FWHM narrowing shows threshold characteristics. The threshold is 0.226μJ/pluse when the film is 93.3 nm and with the increase of film thickness the threshold drop to 0.16μJ/pluse, and the gain increase to 28.2 cm-1. However the thickness can not increase unlimitedly because of high attenuation coefficient and the pump energy can be used up rapidly. So we make the micron and 560 nm film to find the connection between stimulated emission and thickness.
We also study ASE with similar MEH-PPV films spin-coated for different solvent. Compared with the other solvent, chlorobenzene is proper solvent because of it's specifics such as:boiling points, surface tension etc. After the AFM measurement, I confirm that the chlorobenzene film has the most smoothly surface, so chlorobenzene film has the best threshold and gain.
在实验中我们利用旋涂法制作了以甲苯为溶剂的MEH-PPV溶液的三层非对称波导结构的器件,在500 nm的激光泵浦的条件下观察到了MEH-PPV薄膜的受激发射。并且我们发现当泵浦光光强较低时,受激发射的光强也相对较低,谱线的半高宽也比较大,但是随着泵浦光光强的增强,发射光强出现较大的增长,显现出阈值的特性,并且发射谱线的半高宽也有明显的窄化。通过对比测量我们发现随着器件薄膜的厚度的增加器件的阈值有明显的下降,当薄膜厚度为93.3 nm时器件的阈值为0.219μJ/pluse,厚度增加至279.3 nm时,阈值下降至0.162μJ/pluse,而且此时器件的净增益达到28.2 cm-1。因为厚度的增加还有可能使泵浦能量快速耗尽,以及材料具有较高的衰减系数,所以器件薄膜的厚度也不能无限扩大。为了进一步认识厚度与受激发射的关系及规律,我们通过提高溶液的浓度和自然扩散法设计制作了560 nm和微米级别的器件进行研究。
最后对于不同的溶剂在相同的浓度下对波导结构的MEH-PPV薄膜器件的受激发射进行了研究。发现符合最适宜成膜的条件的氯苯溶剂所制作的器件的性能最佳,经过分析认为此器件的薄膜最为平整,通过原子力显微镜也证明此溶剂制作的波导的粗糙度最小。
The organic laser has many potential advantages:easy fabrication, low costs, tunable emission wavelength, large-scale integration. In recent years, conjugated organic semiconductor polymers have been one of the main research directions in organic optoelectronic materials due to their high fluorescence efficiency, large excitation cross section. In this paper, we discuss the amplified spontaneous emission (ASE) characteristics in MEH-PPV film and factors to influence ASE.
Under the pump of 500nm pulse laser, ASE of the MEH-PPV waveguide with asymmetric structures was investigated. We found that the output intensity is lower and the full width at half maximum (FWHM) is wider when the pump intensity is lower. However, with the increasing pump intensity, the quick increase in output intensity y and the FWHM narrowing shows threshold characteristics. The threshold is 0.226μJ/pluse when the film is 93.3 nm and with the increase of film thickness the threshold drop to 0.16μJ/pluse, and the gain increase to 28.2 cm-1. However the thickness can not increase unlimitedly because of high attenuation coefficient and the pump energy can be used up rapidly. So we make the micron and 560 nm film to find the connection between stimulated emission and thickness.
We also study ASE with similar MEH-PPV films spin-coated for different solvent. Compared with the other solvent, chlorobenzene is proper solvent because of it's specifics such as:boiling points, surface tension etc. After the AFM measurement, I confirm that the chlorobenzene film has the most smoothly surface, so chlorobenzene film has the best threshold and gain.
引文
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[3]Chiang C. K, Shirakawa H, Frincher C. R, et al. Electrical conductivity in dope polyacetylene, 1977,39,1098.
[4]Tang C. W, VanSlyke S. A, Organic electroluminescent diodes, Appl Phys Lett,1987,51,913
[5]Burroughes J. H, Bardley D. D. C, Brown A. R, et al, Light-emitting diodes based on conjugated polymers, Nature,1990,347,539.
[6]Schon J. H, Berg S, Kloc Ch, et al, Ambipolar pentacene field-effect transistors and inverters Science,2000,287,022
[7]Schon J. H, Kloc Ch, Dodabalapur A, et al, An organic solid state injection laser, Science,2000, 289,599.
[8]Schon J. H, Meng H, Bao Z, Self-assembled monolayer organic field-effect transistors, Nature, 2001,413,713.
[9]Lawrence J. R., Turnbull G. A.,Samuell I. D. W.,Richards G. J., Burn P. L. Opt. Lett.,2004,29, 869.
[10]Xia R.,Heliotis G, Campoy-Quiles ML., Stavrinou P. N., Bradley D. D. C., Vak D., Kim D. Y. J. Appl. Phys.,2005,98,083101.
[11]Johansson N., Salbeck J., Bauer J., Weissortel F., Brons P., Andersson A., Salaneck W. R. Adv. Mater,1998,10,1136.
[12]于丹,DFB结构聚合物薄膜受激辐射特性的研究.北京.北京交通大学.2008.1,4.
[13]D Moses. High quantum efficiency luminescence from a conducting polymer in solution:A novel polymer laser dye. Appl. Phys, Lett,1992,60(26):3215-3216.
[14]Michael.D. McGehee, Alan. J. Heeger, semiconducting (conjugated) polymers as materials for solid-state lasers, Adv. Mater,2000,1655,1665.
[15]V. G. Kozlov, G Parthasarathy, P. E. Burrows, S. R. Forrest, Optically pumped blue organic semiconductor lasers, Appl. Phys, Lett,1997,144,146.
[16]N. Deepak Kumar, Jayant D. Bhawalkar, and Paras N. Prasad. Solid-state tunable cavity lasing in a poly(para-phenylenevinylene)derivative alternating block co-polymer, Appl. Phys. Lett,71, 999(1997).
[17]Ruidong Xia, George Heliotis, Yanbing Hou, Donal D. C. Btadley. Fluorene-based conjugated polymer optical gain media. Origanic Electronics,2003,4:165.
[18]王立军,刘星元,宁永强,找家民,马凤英,有机/聚合物激光,激光与激光技术,2002,8,12
[19]凌云,有机聚合物光波导的研制.南京.东南大学.2005.14,16.
[20]Z. Yang, H. J. Geise, M. Mehbod, Conductivity and electron density of undoped model compounds of poly(phenylene vinylene). Synth. met.,1990,39(2),137-151.
[21]M. Reufer, J. Feldmann, P. Rudati, A. Ruhl, D. Miiller, K. Meerholz, Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive, Appl. Phys. Lett,2005,86,221102-3
[22]K. Sandros, M. Sundahl, O. Wennerstrom, J. Phys. Chem., Singlet-state diabatic and adiabatic cris-trans photoisomerizations of 4,4'-bis(3.5-di-tert-butylstyryl)stilbenes.1993,97(20) 5291-5294.
[23]D. Oelkrug, A. Tompert, J. Gierschner, H. J. Egelhaaf, M. Hanack, M. Hohloch and E. Sternhuber. Tuning of fluorescence in films and Nanoparticles of Oligophenylenevinylenes. J. Phys. Chem. B.1998,102(11),1902-1907.
[24]G. Heliotis, S. A. Choulis, G. Itskos, R. Xia, R. Murray,P. N. Stavrinou, and D. D. C. Bradley, Low-threshold lasers based on a high-mobility semiconducting polymer, Appl. Phys. Lett,2006, 88,081101-04.
[25]马良,陈婷,陈为健.发光层厚度对红光磷光聚芴电致发光性能的影响,闽江学院学报,2010,31(2),100,103.
[26]娄双玲,于军胜,黎威志,李璐.双层结构有机电致发光器件发光层厚度的优化研究,半导体光电,2007,28(2),195,198.
[27]Richard. H. Friend, Seamus Burns, Graham Denton, Mark Stephens, Nir Tessler, Control of Spontaneous and Stimulated Emission in Conjugated Polymers, IEEE,1997,169,170
[28]高瑞,侯延冰,于丹,滕枫.MEH-PPV薄膜的放大自发发射特性.发光学报.2008,29(1),71,74.
[29]Kozlov. V. G, Forrest. S. R, Curr. Opin. Solid State Mater. Sci.1999,4,203.
[30]Karnutsch. C, Pflumm. C, Helitois. G, Demello. J. C, Bradly. D, C, C, Wang. J, Weimann. T, Haug. V, Gartner. C, Lemmer. U., Appl. Phys. Lett,2007,90,131,104.
[31]CUI. Yanqing, JIANG Yuanru,江元汝,崔延青,纳米ZnS的研究现状及应用,材料导报,2005,19(z1).
[32]刘明,滕枫,孙世菊,刘姗姗,徐征,共轭聚合物MEH-PPV的固态阴极射线发光,发光学报,2003,24(1).
[33]Wang Lianhong, Shu Yonghua, Fan Jing,王连红,舒勇华,樊菁,电子束蒸发制备YBCO超导薄膜研究,低温与超导,2010,38(11).
[34]黄金英,绝缘层对有机薄膜晶体管性能影响的研究,凝聚态物理,北京,北京交通大学,2008,6,10.
[35]袁仁宽,孔凡,欧昌刚,郑怡,张苏洋,杨昌正,鲍希茂,吴兴龙,不同形态MEH-PPV的构象及其光学特性,发光学报,2005,26(5),655,657.
[36]於黄忠,彭俊彪,溶剂及器件结构对MEH-PPV与PCBM电池性能影响,物理化学学报,2007,23(10),1637,1641.
[37]ZHONG. Guo-lun, WANG, Yong-hong, LIN. Jin-qi, Spectral Properties of Porphyrin Doped MEH-PPV as Films and in Chloroform Solutions,发光学报,2010,31(1),119,124.
[38]穆光照,实用溶剂手册,上海,上海科学技术出版社,1999,09,15,511.
[2]Ito. T, Shirakawa. H, Ikeda. S. Simultaneous polymerization and formation of polyacetylene film on the surface of concentrated soluble Ziegler-Type catalyst solution. J. Polym. Sc. Polym. Chem,1974,12.11
[3]Chiang C. K, Shirakawa H, Frincher C. R, et al. Electrical conductivity in dope polyacetylene, 1977,39,1098.
[4]Tang C. W, VanSlyke S. A, Organic electroluminescent diodes, Appl Phys Lett,1987,51,913
[5]Burroughes J. H, Bardley D. D. C, Brown A. R, et al, Light-emitting diodes based on conjugated polymers, Nature,1990,347,539.
[6]Schon J. H, Berg S, Kloc Ch, et al, Ambipolar pentacene field-effect transistors and inverters Science,2000,287,022
[7]Schon J. H, Kloc Ch, Dodabalapur A, et al, An organic solid state injection laser, Science,2000, 289,599.
[8]Schon J. H, Meng H, Bao Z, Self-assembled monolayer organic field-effect transistors, Nature, 2001,413,713.
[9]Lawrence J. R., Turnbull G. A.,Samuell I. D. W.,Richards G. J., Burn P. L. Opt. Lett.,2004,29, 869.
[10]Xia R.,Heliotis G, Campoy-Quiles ML., Stavrinou P. N., Bradley D. D. C., Vak D., Kim D. Y. J. Appl. Phys.,2005,98,083101.
[11]Johansson N., Salbeck J., Bauer J., Weissortel F., Brons P., Andersson A., Salaneck W. R. Adv. Mater,1998,10,1136.
[12]于丹,DFB结构聚合物薄膜受激辐射特性的研究.北京.北京交通大学.2008.1,4.
[13]D Moses. High quantum efficiency luminescence from a conducting polymer in solution:A novel polymer laser dye. Appl. Phys, Lett,1992,60(26):3215-3216.
[14]Michael.D. McGehee, Alan. J. Heeger, semiconducting (conjugated) polymers as materials for solid-state lasers, Adv. Mater,2000,1655,1665.
[15]V. G. Kozlov, G Parthasarathy, P. E. Burrows, S. R. Forrest, Optically pumped blue organic semiconductor lasers, Appl. Phys, Lett,1997,144,146.
[16]N. Deepak Kumar, Jayant D. Bhawalkar, and Paras N. Prasad. Solid-state tunable cavity lasing in a poly(para-phenylenevinylene)derivative alternating block co-polymer, Appl. Phys. Lett,71, 999(1997).
[17]Ruidong Xia, George Heliotis, Yanbing Hou, Donal D. C. Btadley. Fluorene-based conjugated polymer optical gain media. Origanic Electronics,2003,4:165.
[18]王立军,刘星元,宁永强,找家民,马凤英,有机/聚合物激光,激光与激光技术,2002,8,12
[19]凌云,有机聚合物光波导的研制.南京.东南大学.2005.14,16.
[20]Z. Yang, H. J. Geise, M. Mehbod, Conductivity and electron density of undoped model compounds of poly(phenylene vinylene). Synth. met.,1990,39(2),137-151.
[21]M. Reufer, J. Feldmann, P. Rudati, A. Ruhl, D. Miiller, K. Meerholz, Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive, Appl. Phys. Lett,2005,86,221102-3
[22]K. Sandros, M. Sundahl, O. Wennerstrom, J. Phys. Chem., Singlet-state diabatic and adiabatic cris-trans photoisomerizations of 4,4'-bis(3.5-di-tert-butylstyryl)stilbenes.1993,97(20) 5291-5294.
[23]D. Oelkrug, A. Tompert, J. Gierschner, H. J. Egelhaaf, M. Hanack, M. Hohloch and E. Sternhuber. Tuning of fluorescence in films and Nanoparticles of Oligophenylenevinylenes. J. Phys. Chem. B.1998,102(11),1902-1907.
[24]G. Heliotis, S. A. Choulis, G. Itskos, R. Xia, R. Murray,P. N. Stavrinou, and D. D. C. Bradley, Low-threshold lasers based on a high-mobility semiconducting polymer, Appl. Phys. Lett,2006, 88,081101-04.
[25]马良,陈婷,陈为健.发光层厚度对红光磷光聚芴电致发光性能的影响,闽江学院学报,2010,31(2),100,103.
[26]娄双玲,于军胜,黎威志,李璐.双层结构有机电致发光器件发光层厚度的优化研究,半导体光电,2007,28(2),195,198.
[27]Richard. H. Friend, Seamus Burns, Graham Denton, Mark Stephens, Nir Tessler, Control of Spontaneous and Stimulated Emission in Conjugated Polymers, IEEE,1997,169,170
[28]高瑞,侯延冰,于丹,滕枫.MEH-PPV薄膜的放大自发发射特性.发光学报.2008,29(1),71,74.
[29]Kozlov. V. G, Forrest. S. R, Curr. Opin. Solid State Mater. Sci.1999,4,203.
[30]Karnutsch. C, Pflumm. C, Helitois. G, Demello. J. C, Bradly. D, C, C, Wang. J, Weimann. T, Haug. V, Gartner. C, Lemmer. U., Appl. Phys. Lett,2007,90,131,104.
[31]CUI. Yanqing, JIANG Yuanru,江元汝,崔延青,纳米ZnS的研究现状及应用,材料导报,2005,19(z1).
[32]刘明,滕枫,孙世菊,刘姗姗,徐征,共轭聚合物MEH-PPV的固态阴极射线发光,发光学报,2003,24(1).
[33]Wang Lianhong, Shu Yonghua, Fan Jing,王连红,舒勇华,樊菁,电子束蒸发制备YBCO超导薄膜研究,低温与超导,2010,38(11).
[34]黄金英,绝缘层对有机薄膜晶体管性能影响的研究,凝聚态物理,北京,北京交通大学,2008,6,10.
[35]袁仁宽,孔凡,欧昌刚,郑怡,张苏洋,杨昌正,鲍希茂,吴兴龙,不同形态MEH-PPV的构象及其光学特性,发光学报,2005,26(5),655,657.
[36]於黄忠,彭俊彪,溶剂及器件结构对MEH-PPV与PCBM电池性能影响,物理化学学报,2007,23(10),1637,1641.
[37]ZHONG. Guo-lun, WANG, Yong-hong, LIN. Jin-qi, Spectral Properties of Porphyrin Doped MEH-PPV as Films and in Chloroform Solutions,发光学报,2010,31(1),119,124.
[38]穆光照,实用溶剂手册,上海,上海科学技术出版社,1999,09,15,511.