Modifying perovskite solar cells with l(+)-cysteine at the interface between mesoporous TiO2 and perovskite

Abstract

Perovskite solar cells (PSCs) have attracted extensive attention and their which power conversion efficiency (PCE) has rapidly increased from 3.8% to 25.2% in recent years. Interfacial modification is regarded as a highly effective strategy to address the humidity instability and improve the performance of PSCs. In this regard, L(+)-cysteine (L-cy), a typical trifunctional amino acid, is employed to modify the interface between mesoporous TiO₂ (mp-TiO₂) and perovskite. The incorporation of L-cy increases the PCE from 11.5% to 14.4%. Fluorescence measurements show that the electron injection from perovskite to mp-TiO₂ is enhanced due to the interactions between the functional groups (–COOH, –NH₂ and –SH) of L-cy and Ti⁴⁺ ions in mp-TiO₂ and unsaturated Pb²⁺ and I⁻ ions in the perovskite film. This work demonstrates a facile and effective method to achieve high-performance PSCs.