Conductive Layer Thickness Enhanced Lateral Photovoltaic Performances in the Cu(In, Ga)Se2-Based Multilayer Heterostructure

For the photovoltaic effect (PE), the surface potential is suggested to be an adverse factor, and researchers usually try to increase the thickness of the conductive layer or the number of strip electrodes to avoid it. However, the potential can still not be eliminated. More importantly, the huge cost has to be paid, and the photovoltaic performances are largely reduced. While the drawback of potential in PE may become excellent merit in lateral PE (LPE) due to their different working mechanisms. Moreover, the decreasing thickness of the conductive layer may be inversely used as an efficient method to modulate the LPE performances. In this paper, the indium tin oxide (ITO) conductive layer thickness-dependent LPE responses are well studied in the copper indium gallium selenide (CIGS) heterostructure. The LPE response is significantly improved with ITO thickness decreasing from 150 to 10 nm, and the thickness-dependent enhancement is strongly dependent on the illumination intensity, especially in high illumination intensities, a nonmonotonic thickness dependence is obtained. In addition, it is found that the heterostructure exhibits an ultrafast response speed of ~14.5 μs/~15.0 μs, and what is more, the response time nearly remains constant without depending on the ITO thickness.