PHOTOVOLTAIC AND PHOTOCONDUCTIVE PROPERTIES OF ALUMINUM POLY(P-PHENYLENE VINYLENE) INTERFACES

Photoconductive and photovoltaic properties of Al/PPV/ITO sandwich devices were investigated by measuring steady-state photocurrents resulting from illumination through the Al electrode. A built-in potential (V(bi)) was detected at the Al/PPV interface. The voltage dependence of the photocurrent in the vicinity of V(bi) was measured at 1 mW/cm2 of incident illumination to give an open-circuit voltage and a short-circuit current of 1.2 V and 6 x 10(-7) A/cm2, respectively. The dependences of the short-circuit current on excitation wavelength and illumination intensity are presented and the C-V characteristics of the Al/PPV interface are analyzed. The quantum collection efficiency decreased from 5% to 1% as the intensity of illumination increased from 10(-5) to 1 mW/cm2. The photovoltaic conversion power efficiency was about 0.07% for intensities approaching 1 mW/cm2. The V(bi) value was accounted for by surface band-bending at the Al/PPV interface.