Cd2SnO4/CdS/Cu2O/Ag Solar Cell Obtained by Chemical Techniques

By first time Cd2SnO4/CdS/Cu2O/Ag heterojunctions were studied for their application in solar cells. The heterostructure was deposited on glass-substrate and obtained by chemical techniques: i) Cd2SnO4 as TCO by solgel, ii) CdS as n-layer by chemical bath deposition and iii) Cu2O as p-layer by spray pyrolysis. The thicknesses of the Cd2SnO4 and CdS layers were 290 nm and 135 nm, respectively. Different thicknesses of Cu2O (tau) were used to study the effect of this parameter on the solar cell performance (135, 185, 220, 350 and 800 nm). The best photovoltaic parameters were obtained with tau = 220 nm achieving an V-OC = 346 mV, J(SC) = 1.57 mA/cm(2), FF = 33.4 and eta = 0.18%. External quantum efficiency shows current generated at energy values below Cu2O and CdS band gaps. This contribution of current is mainly attributed to defects in the Cu2O lattice that result in a source of energy levels within the band gap.