Reducing the interfacial energy loss via oxide/perovskite heterojunction engineering for high efficient and stable perovskite solar cells

Organic-inorganic perovskite solar cells (PSCs) have attracted much attentions due to their excellent photoelectric properties and low-cost fabrication. However, the performance of PSCs is seriously affected by the charge recombination at interface. Herein, we conducted a metal oxide/perovskite heterojunction engineering approach by utilizing a highly efficient LiF-doped SnO2 (SnO2:LiF)/perovskite interface. The theoretical and experimental results show that the LiF doping could modulate the lattice constant of SnO2, reduce the lattice mismatch between SnO2 and perovskite and hence reduce the trap states. Furthermore, LiF doping could enhance the conductivity of SnO2 ETL, improve the energy band alignment at interface, and enhance the charge transfer between SnO2 and perovskite. Consequently, the PSC based on SnO2:LiF/perovskite heterojunction achieves a high power conversion efficiency (PCE) of 21.33% with a V-oc of 1.13 V, a J(sc) of 24.00 mA/cm(2) and an FF of 0.78. Meanwhile, the devices exhibit improved stability under continuous AM 1.5G light illumination and high humidity conditions. Our work provides an oxide/perovskite heterojunction avenue to further increase the efficiency and stability of PSCs.