Enhanced Selective Charge Collection with Metal–Insulator–Semiconductor Junction in Electron Transport Layer‐Free Perovskite Solar Cells

Abstract

AbstractElectron transport layer (ETL)‐free perovskite solar cells (PSCs) have witnessed great progress via material and interface engineering. Enlighten by the wisdom from an old story of efficient silicon solar cells design, highly efficient MINP (metal/insulator/n‐type perovskite/p‐type spiro‐MeOTAD) PSC with polar insulating inter‐layer (PIIL) modified fluorine‐doped tin oxide (FTO) is reported as electron selective contact. The PIIL forms metal‐insulator‐semiconductor (MIS) junction with FTO and perovskite layer, while the n‐type perovskite forms P‐N junction with p‐type spiro‐MeOTAD. Unlike the classic MINP silicon solar cells where the I‐layer is usually neutral tunneling layer, the PIIL here optimizes the energy level alignment at the FTO/perovskite interface with its intrinsic electronic polarity while acting as an effective tunneling layer. Also, the functional group of the PIIL passivates the FTO/perovskite interface defects thus suppressing carrier recombination thereof and enhancing all device performance parameters simultaneously. Accordingly, the power conversion efficiency is greatly improved from 12.82% to 19.75%. With the enhanced electron collection and decreased carrier recombination of the MIS junction, this collaborative effect of interface engineering and defect passivation contribute to more stable ETL‐free PSC with less hysteresis. This work highlights the potential of novel device and interface design for simple‐structured, efficient and cost‐effective PSCs.