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 (C=O, —NH), valeric acid chain (—COO^-), and tetrahydrothiophene (S—C) 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 (V_oc) 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.

Keywords

chemical coordination / defect passivation / tin perovskite solar cells / Vitamin H Biotin complex / wide bandgap

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