Back-interface regulation for carbon-based perovskite solar cells

Perovskite solar cells (PSCs) based on carbon electrodes (C–PSCs) have drawn considerable attention due to their advantages such as high stability and low cost, which are required performance indicators for commercialization of this new-generation photovoltaic technology. However, the power conversion efficiency of C–PSCs is unsatisfactory compared with that of PSCs based on Au electrodes (Au–PSCs). In particular, the performance loss of C–PSCs mainly derives from the poor back-interface contact between perovskite and carbon electrodes (CEs). The properties of back interface dominate the carrier extraction, transfer and recombination in C–PSCs. Back-interface regulation has been recognized as an effective way to improve the efficiency of C–PSCs. In this review, recent back-interface regulation for C–PSCs are systematically reviewed from three perspectives: (1) perovskite engineering, (2) CEs engineering, and (3) interlayer engineering. Promising research directions for C–PSCs are also suggested to further promote the future commercialization of C–PSCs.