Thickness dependent properties of electro-chemical-photovoltaic (ecpv) cells formed with chemically deposited CdS films

Thin polycrystalline cadmium sulphide photoelectrodes of various thicknesses have been deposited on polished stainless steel substrates by a chemical bath deposition technique. The electrochemical photovoltaic (ecpv) cells were formed with these photoanodes. Short circuit current (Isc) and open circuit voltage (Voc) are recorded under 100 mW/cm² light intensity. It is found thatIsc increases with increase in thickness of the photoanode whereasVoc remains more or less constant. The other cell parameters, maximum power output (Pm) and efficiency (η) are found to improve with increasing thickness, while fill factor (f.f.) varies slightly with the photoanode thickness. The semiconductor-liquid space charge region capacitances in the dark were measured. The variation of 1/C ² versus applied reverse biasV is nonlinear. The deviation from straight line behaviour is attributed to the existence of surface states and degeneracy of states. The flat band potential is determined from the extrapolation of the (1/C ²) −V plot to the voltage axis, and is found to vary with the thickness of the photoanode.