Highly transparent ternary bulk-heterojunctions for semi-transparent organic photovoltaics

Abstract

This report presents organic ternary bulk-heterojunctions (BHJ) active layers with record average visible transmittance (AVT). The incorporation of wide bandgap organic semiconductor PTAA as a third compound into the donor diluted PCE10 : COTIC-4F blend system increases AVT up to 81% and simultaneously enhances charge transport and photogeneration in the ultraviolet spectral range. Successive replacing COTIC-4F acceptor with SiOTIC-4F enhances the open-circuit voltage and elevates the opaque device performance from 4.41% to 5.77%, while maintaining the excellent AVT of the BHJ layer at around 80%. A comprehensive device physics analysis of the organic solar cells with optimized and reproducible opaque back electrode was conducted for understanding the generation–recombination processes in different donor : acceptor blends. Ultimately, semi-transparent OSCs (ST-OSCs) were fabricated utilizing the studied highly transparent ternary BHJ active layers demonstrating their potential for the development of semi-transparent photovoltaics.