PbX(OH) (X=Cl, Br, I) is considered one of the effective encapsulation matrixes to improve the stability and luminescence efficiency of perovskite. Several strategies have been explored to construct perovskite@PbBr(OH) composites with high photoluminescence quantum yield. However, there is limited research on their precise growth kinetics mechanism and morphology control. Here, PbBr2 microwires (MWs) were applied to act as the lead source and serve as a skeleton frame for the growth of CH3NH3PbBr3 (MAPbBr3) MWs. The structures transition from MAPbBr3 to MAPbBr3@PbBr(OH) MWs were triggered by the synergistic effect of H2O and CH3NH3OOCCH3 (methylamine acetate, MAAc). All components and synthesis processes used in this system are explicit which allows a more in-depth exploration of the MAPbBr3@PbBr(OH) formation kinetics. The results indicate that the hydrolysis of MAAc provides OH- and partly replaces Br- ions in MAPbBr3 to form MAPbBrxAc3-x intermediate, which induces the transformation of MAPbBr3 into PbBr(OH) and until the stable MAPbBr3@PbBr(OH) microwires are formed. Based on this growth kinetics process, utilizing H2O-MAAc and extra sodium halide (NaCl, NaI) mixture can synthesize MAPbBrnX3-n@PbX(OH) (X=Cl, I) microwires successfully. Our study can open a new avenue for developing high-efficiency and high-stability fluorescent hybrid perovskites for three primary color detectors, lasing cavities, and sensors.
Xiaoyan Gan,Kegui Li,Longtao Du,Ruoqi Wang,Yuge Chang,Liling Guo,Hanxing Liu
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.
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