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

Abstract

• LiF doping reduce the surface defects and relieve lattice mismatch between SnO 2 and perovskite. • LiF doping enhance the electron transfer at SnO 2 /perovskite heterojunction interface. • The optimized PSCs exhibited a PCE of 21.33% with a V oc of 1.13 V, and a FF of 0.78. • The unencapsulated device exhibits good light, and long-term storage stabilities. 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 SnO 2 (SnO 2 :LiF)/perovskite interface. The theoretical and experimental results show that the LiF doping could modulate the lattice constant of SnO 2 , reduce the lattice mismatch between SnO 2 and perovskite and hence reduce the trap states. Furthermore, LiF doping could enhance the conductivity of SnO 2 ETL, improve the energy band alignment at interface, and enhance the charge transfer between SnO 2 and perovskite. Consequently, the PSC based on SnO 2 :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.