Efficient Sn‐Pb Perovskite Solar Cells Through Inhibiting Hole Accumulation

Abstract Sn‐Pb perovskite solar cells (PSCs) own the highest theoretical efficiency due to their ideal bandgap. However, the efficiency of Sn‐Pb PSCs remains 22–23% at present, which is much lower than Pb‐based PSCs. One key reason lies in the Sn 2+ oxidation issue. Here, this study demonstrates that apart from well‐known chemical environmental oxidation, photo‐generated holes and their accumulation are also a critical factor for Sn 2+ oxidation in Sn‐Pb PSCs. To address this issue, a non‐planar hole transport layer (HTL) of P3CT/Me‐4PACz is designed through solution micelle regulation. P3CT/Me‐4PACz will form a 3D HTL film with a spike‐like structure penetrating Sn‐Pb perovskite bulk to accelerate hole extraction, thus inhibiting holes accumulation and Sn 2+ oxidation. Resulted Sn‐Pb PSCs exhibit the highest efficiency of over 24% with good operational stability, retaining 82% of initial efficiency after continuous MPP tracking for 1000 h at an elevated temperature of 55 °C.