Cherasse Marie, Heshmati Niusha, Urban Joanna M, Ünlü Feray, Spencer Michael S, Frenzel Maximilian, Perfetti Luca, Mathur Sanjay, Maehrlein Sebastian F
Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Berlin, Germany.
LSI, CEA/DRF/IRAMIS, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, Palaiseau, France.
Small. 2025 May;21(21):e2500977. doi: 10.1002/smll.202500977. Epub 2025 Apr 18.
Lead halide perovskites (LHPs) are promising materials for efficient photovoltaic devices; however, they often encounter limited structural stability and degradation problems that limit their technological potential. This study investigates a novel perovskite composition consisting of (Cs, MA, FA, GA)PbBr abbreviated as (4cat)PbBr, to effectively enhance phase stability and optoelectronic characteristics. The spectroscopic data reveal improved structural order, electronic properties, and dynamic lattice response in a cubic phase, which is uniquely stabilized by the specific cation composition down to 80 K. Superior optoelectronic properties are verified by increased photoluminescence (PL) and 20-fold higher electron mobility, when compared to the single-cation composition, MAPbBr. Notably, the ultrafast Terahertz-induced Kerr effect (TKE) reveals a dominating 1.1 THz octahedral twist mode, also observed in MAPbBr, however with a doubled phonon coherence time in (4cat)PbBr at 80 K. The observation of higher structural order in the 4-cation composition is thus reflected by the prolonged lattice coherences, indicating enhanced dynamic screening effects that can explain the improved optoelectronic properties of (4cat)PbBr. This study therefore sheds light on the influence of the A-site cation composition on the inorganic sublattice and its coherent dynamics, highly relevant to perovskite-based photovoltaic and optoelectronic technologies.
卤化铅钙钛矿（LHPs）是用于高效光伏器件的有前景的材料；然而，它们经常遇到结构稳定性有限和降解问题，这限制了它们的技术潜力。本研究调查了一种新型钙钛矿组合物，其由（Cs、MA、FA、GA）PbBr（简称为（4cat）PbBr）组成，以有效提高相稳定性和光电特性。光谱数据揭示了立方相结构有序性、电子性质和动态晶格响应的改善，该立方相通过特定的阳离子组成在低至80K时独特地稳定下来。与单阳离子组合物MAPbBr相比，通过增强的光致发光（PL）和高20倍的电子迁移率验证了优异的光电性质。值得注意的是，超快太赫兹诱导的克尔效应（TKE）揭示了占主导地位的1.1太赫兹八面体扭曲模式，在MAPbBr中也观察到了该模式，然而在80K时（4cat）PbBr中的声子相干时间加倍。因此，在4阳离子组合物中更高结构有序性的观察结果通过延长的晶格相干性得以体现，这表明增强的动态屏蔽效应可以解释（4cat）PbBr改善的光电性质。因此，本研究揭示了A位阳离子组成对无机亚晶格及其相干动力学的影响，这与基于钙钛矿的光伏和光电技术高度相关。
