Photocurrent spectral responses in poly (2,5-dimethoxy-p-phenylenevinylene) devices

We report the spectral response of the photocurrent in the sandwich configuration of poly (2,5-dimethoxy-p-phenylenevinylene) (DMPPV ) devices. The photocurrent spectral responses are dependent on the polarity of the illuminated surface and the electrodes. The polarity-dependent photocurrent is modeled on a basis where charge carrier drift plays a dominant mechanism and hole transport is predominant over electron transport. The model can explain the results for the Au/DMPPV/Au symmetric configuration. The model cannot however explain the results for the indium-tin oxide (ITO)/DMPPV/Al device. The response for the light incident on the Al side is also reported. The spectral dependence is also studied as a function of bias electric field. Mechanisms leading to the behavior of the photocurrent spectral dependence are speculated.