Theoretical evaluation of the realizable power conversion efficiency and the possible scheme for hole-transport-layer-free carbon-cathode CsPbI2Br solar cells

Abstract Hole-transport-layer (HTL)-free carbon-cathode CsPbI 2 Br solar cells have gained notable attention because of the good balance between light absorption and improved stability, as well as the cost advantage. However, the power conversion efficiency (PCE) experimentally realized for the related solar cells of < 16% is necessarily improved for possible practical application. In this study, the impact of the interfacial defect density between CsPbI 2 Br and the carbon cathode that is one of the most pivotal factors influencing the PCE improvement is studied, and meanwhile a feasible scheme using a thin AlO x passivation layer to block electrons and allow hole tunneling is proposed. The PCE of 19.68% is predicted for HTL-free carbon-cathode CsPbI 2 Br solar cells.