Radical scavenger-driven oxidation prevention and structural stabilization for efficient and stable tin-based perovskite solar cells

Tin (Sn)-based perovskite solar cells (PSCs) have emerged as promising alternatives to lead-based PSCs owing to their lower toxicity and desirable optoelectronic properties. However, the instability of Sn-based perovskites and the vulnerability of the hole-transport layer (HTL), particularly poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), under oxidative environments remain significant challenges. In this study, we incorporated 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) as a radical scavenger at the HTL/perovskite interface in p-i-n PSCs to suppress Sn²⁺ oxidation through its radical scavenging properties, promote controlled growth of Sn-based perovskite films, and stabilize PEDOT:PSS by mitigating oxidative degradation. These effects resulted in improved crystallinity and reduced recombination losses leading to enhanced device performance. The power conversion efficiency of the PSCs increased from 11.08% to 13.42% upon the incorporation of TEMPOL, accompanied by improved operational stability. This study offers a promising route for addressing the key issues of Sn-based PSCs, paving the way for durable and efficient lead-free PSCs.