PHOTOCURRENT SPECTRAL RESPONSES IN POLY(2,5-DIMETHOXY-P-PHENYLENEVINYLENE) DEVICES

We report the spectral response of the photocurrent in the sandwich co nfiguration 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 ph otocurrent is modeled on a basis where charge carrier drift plays a do minant mechanism and hole transport is predominant over electron trans port. The model can explain the results for the Au/DMPPV/Au symmetric configuration. The model cannot however explain the results for the in dium-tin oxide (ITO) /DMPPV/Al device. The response for the light inci dent on the Al side is also reported. The spectral dependence is also studied as a function of bias electric field. Mechanisms leading to th e behavior of the photocurrent spectral dependence are speculated.