In this article, the photoelectric behavior of sandwich type n-GaAs/orange dye, vinyl-ethynyl-trimethyl-piperidole/conductive glass sensors was investigated. Devices were fabricated by employing electrodes of heavily doped (2 x 1018 cm(-3)) n-type GaAs and conductive glass of In2O3, whereas the electrolyte was a mixture of orange dye (OD) and vinyl-ethynyl-trimethyl-piperidole (VETP). Dark current voltage (I-V) characteristics of the devices exhibited small rectification behavior with zero offset voltage, which shows the presence of electrochemical effects in the devices. Photo-induced alternating and direct open-circuit voltages and short-circuit currents were investigated by using infira-red, red, green and blue light sources, and it was observed that the devices were sensitive to the wavelengths ranging 550 nm-700 nm. Based on the observed optical spectra of OD-VETP electrolyte and GaAs a plausible band diagram of the device was developed to explain the observed I-V characteristics and to draw its equivalent circuit diagram. (c) 2008 Elsevier B.V. All rights reserved.