Abstract:Poly (3,4-ethylene dioxythiophene)(PEDOT): Poly (styrene sulfonate)(PSS) has attracted a lot of interest for application in organic electronics due to good stability and high electronic conductivity in its doped state. Indeed, thin layers of PEDOT: PSS was regularly used in light emitting diodes (PLEDs) as hole injection and transportation layer. Here, Doping and dedoping states of PEDOT:PSS were studied by absorbance spectra and Raman spectra. A new absorption band centered at 620 nm was observed on dedoped PEDOT:PSS. Consistently, Raman signals of dedoped PEDOT:PSS are resonantly intensified since the Raman excitation wavelength (633 nm) is set in the enhanced absorption band. So it gives a sensitive way to study the doping and dedoping states of PEDOT:PSS. Furthermore, for the encapsulated polymer light-emitting diodes, Raman spectroscopy is a powerful way to study the polymer layers inside the devices.
[1] Arias A C, et al. Phys. Rev. B, 1999, 60: 1854. [2] Louwet F, et al. Synthetic Metals, 2003, 135: 115. [3] Cao Y, et al. Synthetic Metals, 1997, 87: 171. [4] Tomas Johansson, et al. Synthetic Metals, 2002, 129: 269. [5] XU Xiao-xuan, LIN Hai-bo, WU Zhong-chen, et al(徐晓轩, 林海波, 武中臣, 等). J. Infrared and Millimeter Waves(红外与毫米波学报), 2003, 22(1): 63. [6] YAN Xun-ling, DONG Rui-guo, WANG Qiu-guo(闫循领, 董瑞国, 王秋国). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2004, 24(5): 576. [7] ZHENG Jun-wei, GU Ren-ao, LU Tian-hong(郑君伟, 顾仁敖, 陆天虹). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2000, 20(5): 689. [8] Peter K H Ho, et al. Nature, 2000, 404: 481. [9] Kim Ji-Seon, et al. Adv. Mater., 2002, 14: 206. [10] Lapkowski M, et al. Synthetic Metals, 2000, 110: 79.