Dual‐Source Defect Managing of Tin–Lead Perovskite for Efficient All‐Perovskite Tandem Solar Cells

Abstract All‐perovskite tandem solar cells (TSCs) hold a great promise to break the Shockley‐Queisser (S‐Q) efficiency limit of single‐junction solar cells. However, the inferior performance of the tin‐lead (Sn–Pb) mixed perovskites based narrow‐bandgap bottom subcells largely limits the development of all‐perovskite TSCs due to the serious defects assisted non‐radiative charge recombination loss, especially at the perovskite/electron charge transport layer (ETL) interface. Herein, a dual‐source defect managing strategy is demonstrated to modify the top surface of Sn–Pb mixed perovskites. Specifically, ethylenediammonium diiodide (EDAI 2 ) and (3‐mercaptopropyl) trimethoxysilane (MPTS) are simultaneously introduced to passivate the organic cations and metal cations related defects, respectively. The strong interactions between the passivators and Sn–Pb perovskite result in effectively reduced non‐radiative carrier recombination, obviously suppressed Sn 2+ oxidation and accelerated carrier transportation at the perovskite/ETL interface. Ultimately, a champion efficiency of 22.7% for single‐junction Sn–Pb solar cells and an impressive efficiency of 28.26% for the all‐perovskite TSCs are achieved based on the dual‐source defect managing strategy.