Counter‐Doping Effect by Trivalent Cations in tin‐based Perovskite Solar Cells

Abstract Tin (Sn) ‐based perovskite solar cells (PSCs) normally show low open circuit voltage due to serious carrier recombination in the devices, which can be attributed to the oxidation and the resultant high p‐type doping of the perovskite active layers. Considering the grand challenge to completely prohibit the oxidation of Sn‐based perovskites, a feasible way to improve the device performance is to counter‐dope the oxidized Sn‐based perovskites by replacing Sn 2+ with trivalent cations in the crystal lattice, which however is rarely reported. Here, the introduction of Sb 3+ , which can effectively counter‐dope the oxidized perovskite layer and improve the carrier lifetime, is presented. Meanwhile, Sb 3+ can passivate deep‐level defects and improve carrier mobility of the perovskite layer, which are all favorable for the photovoltaic performance of the devices. Consequently, the target devices yield a relative enhancement of the power conversion efficiency (PCE) of 31.4% as well as excellent shelf‐storage stability. This work provides a novel strategy to improve the performance of Sn‐based PSCs, which can be developed as a universal way to compensate for the oxidation of Sn‐based perovskites in optoelectronic devices.