Chlorinated-Ti3C2TF as a dual-functional buried interface on SnO2 electron-transporting layers for 25.09% high-performance n–i–p perovskite solar cells

Abstract

Fluorinated titanium carbide MXenes (Ti₃C₂T_F) have been proven as interfacial materials for hole transport layers in perovskite solar cells (pero-SCs). The surface terminals of Ti₃C₂T_F can be adjusted to regulate the work function (WF) of electron transport layers (ETLs). In this work, Ti₃C₂T_F,OH,O was treated with HCl to obtain Cl-terminated Ti₃C₂T_F (named Ti₃C₂T_F,Cl). The resulting Ti₃C₂T_F,Cl was employed as a buried interlayer between SnO₂ and the perovskite, which provides the dual functions of reducing the WF of SnO₂, leading to good ohmic contact between the ETL and the perovskite, and facilitating the growth of the perovskite and reducing lattice stress via alteration of the surface energy of the ETL and lattice matching with the perovskite. n–i–p pero-SCs based on FA_0.92MA_0.08PbI₃ achieved an excellent power conversion efficiency (PCE) of 25.09% with an open circuit voltage of 1.18 V. The optimized pero-SCs exhibit improved stability in N₂, light soaking conditions, and air with a relative humidity of 30–40%. Additionally, Ti₃C₂T_F,Cl performs well in large-scale devices (1.1 cm²) with a PCE of 20.62%, and is adaptable to pero-SCs with different perovskite (FA_0.85MA_0.15PbI_2.55Br_0.45), which achieves an exceptional PCE of 24.05% and a high fill factor of 84.52%.