Wang Feifan, Huber Lucas, Maehrlein Sebastian F, Zhu X-Y
Department of Chemistry, Columbia University, New York, New York 10027, United States.
J Phys Chem Lett. 2021 May 27;12(20):5016-5022. doi: 10.1021/acs.jpclett.1c00918. Epub 2021 May 21.
Optical anisotropy originates from crystalline structures with low symmetry and governs the polarization-dependent light propagation. Optical anisotropy is particularly important to lead halide perovskites that have been under intense investigation for optoelectronic and photonic applications, as this group of materials possesses rich structural phases that deviate from the high-symmetry cubic phase. Here we apply 2D optical Kerr effect spectroscopy to quantify the optical anisotropy in single-crystal methylammonium lead bromide (MAPbBr). We determine the strong photon energy dependence of optical anisotropy near the band gap and show the dramatic change in optical anisotropy across phase transitions. We correlate the optical anisotropy with the structural anisotropy and demonstrate the tuning of optical anisotropy by alloyed CsMAPbBr perovskite crystals.
光学各向异性源于低对称性的晶体结构，并控制着与偏振相关的光传播。光学各向异性对于卤化铅钙钛矿尤为重要，这类材料因其具有丰富的偏离高对称立方相的结构相，而一直是光电和光子应用领域的研究热点。在此，我们应用二维光学克尔效应光谱法来量化单晶甲基溴化铅（MAPbBr）中的光学各向异性。我们确定了带隙附近光学各向异性对光子能量的强烈依赖性，并展示了相变过程中光学各向异性的显著变化。我们将光学各向异性与结构各向异性相关联，并证明了通过合金化的CsMAPbBr钙钛矿晶体对光学各向异性的调控。
