High-Quality Thiophene-Based Two-Dimensional Perovskite Films Prepared with Dual Additives and Their Application in Solar Cells

This study explores the optimization of (TMA)2MA4Pb5I16 perovskite films by regulating the film quality through the addition of MACl and MAAc additives. We found that adding MACl resulted in a film of larger grains with a power conversion efficiency (PCE) of 5.34%, while excessive MACl led to the formation of low-dimensional phases. Adding 7.5% MAAc improved the film quality with a PCE of 5.64%, although excessive MAAc induces pores and smaller grains. To address these issues, we proposed the combined use of MACl and MAAc additives, resulting in films with a larger grain size, smoother surface, and denser structure. Remarkably, the addition of MAAc + MACl achieved a champion PCE of 8.86% with good reproducibility. Mechanism studies revealed that TMA and MAAc formed a stable complex with PbI2 in solution, disrupting nucleation laws and promoting the formation of nuclei, leading to denser films with smaller grains. Additionally, the MACl treatment effectively promoted grain growth, resulting in high-quality films. This study presents novel insights into dual additive usage and their role in film crystallization, offering valuable guidance for the preparation of high-performance perovskite films.