Enhancing average visible transmittance of CdS buffer layer for CuInGaSe based semi-transparent photovoltaics: metal ion substitution approach

Integrating Semi-Transparent Photovoltaics (STPV) in buildings is the state-of-the-art application of thin-film photovoltaic (PV) technology, where $CuI{\mathrm{n}}_{1-\mathrm{x}}G\mathrm{a}_{\mathrm{x}}Se2$ (CIGS) STPV cell shows promising outcomes. One possible reason for the reduced visible transparency of STPV devices is the undesired partial absorption of the visible spectrum by the cadmium sulfide (CdS) buffer layer. Further reducing this layer’s thickness to increase the average visible transmittance (AVT) will cause shunt losses, affecting the cell performance. This paper assesses the prospect of incorporating Zn in CdS to enhance the AVT of the buffer layer. A significant increase (24%) in AVT is observed in Zn-incorporated CdS film. The improved structural and optical properties and pin-hole-free, uniform morphology suggest that the substituted film is suitable as a buffer layer for CIGS-based STPV devices.