Erbium chloride-mediated nucleation/crystallization control for high-performance tin-based perovskite solar cells

Tin-halide perovskite solar cells (THPSCs), while offering low toxicity and high theoretical power conversion efficiency, suffer from inferior device performance compared to lead-based counterparts. The primary limitations arise from challenges in fabricating high-quality perovskite films and mitigating the oxidation of Sn²⁺ ions, which leads to severe non-radiative voltage losses. To address these issues, we incorporate the rare-earth element erbium chloride (ErCl₃) into PEA_0.15FA_0.70EA_0.15SnI_2.70Br_0.30 perovskite to effectively control the nucleation and crystal growth, significantly influencing the morphology of the perovskite films. As a result, the ErCl₃-processed THPSC exhibits an impressive open-circuit voltage (V_OC) of 0.83 V and power conversion efficiency (PCE) of 14.0% with the superior light and air stability, compared to the control device (V_OC = 0.77 V and PCE = 12.8%). This ErCl₃-strategy provides a feasible solution for high-performance THPSCs by regulating nucleation/crystallization kinetics and mitigating excessive crystal defects during the preparation process of lead-free perovskites.