In the two-step process of preparing perovskite films, the chemical properties of the PbI2 solution play an important role in determining the phase stability of the perovskite films. Sungkyunkwan University Nam-Gyu Park et al. reported the sulfoxide salt controlled crystallization of α-phase formamidine lead iodide (FAPbI3) stabilized in perovskite solar cells through additive engineering of PbI2 solution .
In situ grazing incidence wide-angle X-ray scattering studies show that trimethylsulfoxide iodide (TMSOI) additive produces ordered solvated quasicrystals PbI2, which facilitates the transformation of PbI2 into the alpha phase when reacting with FAI at room temperature FAPbI3.
Therefore, the photovoltaic performance and stability of perovskite solar cells are enhanced due to the improved photovoltaic properties of perovskite films. The best-performing device has a power conversion efficiency of 24.65% under AM 1.5G illumination. The unpackaged device retained 96.40% of its initial efficiency after 1000 hours of storage at room temperature and relative humidity of 30-40%.
Yalan Zhang, Tinghuan Yang, Sang-Uk Lee, Shengzhong Liu, Kui Zhao, Nam-Gyu Park, Stabilizing α-Phase FAPbI3 Perovskite Induced by an Ordered Solvated Quasi-Crystalline PbI2, ACS Energy Letters, 2023.
DOI: 10.1021/acsenergylett.3c02455