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[摘要]：The dc photocurrent spectra of the indium tin oxide/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/poly (2-methoxy-5-(2 ' -ethylhexyloxy)-1,4-phenylenevinylene) Al (ITO/PEDOT: PSS/MEH-PPV/Al) device are measured for three different MEHPPV thin-film thicknesses in a wide range of bias voltages and for several incident light intensities. The device operation is modeled based on a singlet exciton diffusion and hole polaron drift and diffusion. The Poole-Frenkel transport and the bimolecular Langevine recombination for hole polarons are assumed. The extrinsic photocarrier generation through singlet exciton dissociation on the electrodes and charge transfer in bulk of the polymer film is discussed. We considered three intrinsic charge-carrier photogeneration mechanisms: exciton-exciton annihilation, hot-exciton dissociation, and field dissociation. It is shown that the photocurrent is dominated by the field dissociation of singlet excitons. Experimental results compared to model predictions indicate that absorption coefficient of the MEH-PPV film is thickness dependent. This surprising result is experimentally investigated and confirmed. Excellent agreement between theory and experiment for all themeasured photocurrent spectra is achieved. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3594090] |
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