Multi-interface engineering for all-solution-processed kesterite solar cells

Abstract

The interface contact issue, surface defects, and energy level mismatches have significantly limited the optoelectronic performance of solution-processed transparent conductive window layers for use in thin-film solar cells. In this work, these challenges are systematically addressed by employing molecular engineering to regulate the multiple interfaces of ZnO nanoparticles (ZnO-nps)/silver nanowires (AgNWs) window layers in kesterite solar cells. The interface molecular engineering enhances the conformal deposition of ZnO-nps on rough Cu₂ZnSn(S, Se)₄ (CZTSSe)/CdS substrates, passivates hydroxyl defects in ZnO-nps, and optimizes energy level alignment at the ZnO-nps/AgNWs interface. These advancements enable us to achieve a certified total area efficiency of 14.3%, marking a significant milestone for all-solution-processed kesterite solar cells. Furthermore, the solution-processed window layer forms a robust and flexion-tolerant lateral conductive network, imparting excellent flexibility to the cells. This development provides a critical technical foundation to support the low-cost and simpler preparation of thin-film solar cells in future commercialization.