Efficient Environment-friendly Lead-free Tin Perovskite Solar Cells Enabled by Incorporating 4-Fluorobenzylammonium Iodide Additives

Development of tin (Sn)-based perovskite solar cells (PSCs) largely lags behind that of lead counterparts due to fast crystallization process of Sn perovskite and numerous defects in both bulk and surface of Sn perovskite films. Herein, this work reports a facile strategy of introducing 4-fluorobenzylammonium iodide (FBZAI) as additives into Sn perovskite precursor to synergistically modulate the roles of benzylamine and fluorine in Sn-based PSCs. Incorporation of FBZAI can increase crystallinity, passivate defects, and inhibit the oxidation of Sn2+, leading to suppression of nonradiative recombination and enhancement of charge transport and collection in devices. As a result, the best-performing Sn-based PSC with the FBZAI additive achieves the maximum PCE of 13.85% with the enhanced fill factor of 77.8% and open-circuit voltage of 0.778 V. Our unencapsulated device exhibits good stability by maintaining 95% of its initial PCE after 160 days of storage.

Automated summary

This work presents a facile strategy of introducing 4-fluorobenzylammonium iodide (FBZAI) as additives into Sn perovskite precursor to modulate the roles of benzylamine and fluorine in Sn-based perovskite solar cells (PSCs). The incorporation of FBZAI enhances the crystallinity, passivates defects, and inhibits the oxidation of Sn2+, leading to improved charge transport and collection in devices. The best-performing Sn-based PSC with the FBZAI additive achieves a maximum power conversion efficiency (PCE) of 13.85% with enhanced fill factor and open-circuit voltage. The unencapsulated device also exhibits good stability with a PCE retention of 95% after 160 days of storage.