Record power conversion efficiency in wide bandgap lead-free perovskite solar cells enabled by a natural Vitamin H (Biotin) complex

Abstract

This study introduces a multifunctional coordination approach to enhance wide bandgap (WBG) tin (Sn) perovskite solar cells (PSCs) by incorporating a naturally derived Vitamin H (Biotin) complex into the perovskite precursor. The Biotin complex exhibits strong chemical interaction with Sn2+ via its ureido ring (CO, NH), valeric acid chain (COO−), and tetrahydrothiophene (SC) functionalities. This multidentate interaction further helps to regulate crystal growth kinetics, resulting in compact, pinhole-free films with enhanced surface homogeneity. Furthermore, Biotin effectively passivates uncoordinated Sn sites, mitigates Sn2+ oxidation, and suppresses antisite defects, thereby reducing non-radiative recombination and ion migration. As a result, the optimized device demonstrates a record-high power conversion efficiency of 12.8% (independently certified at 12.5%) and an open-circuit voltage (Voc) of 1.03 V for WBG Sn PSCs. Notably, the device exhibits outstanding ambient stability, retaining almost 80% of its initial efficiency after 1460 h of storage without encapsulation, highlighting the potential of the Biotin complex for high-performance and durable lead-free perovskite photovoltaics. (Figure presented.).