Enhanced Third Harmonic Generation in Lead Bromide Perovskites with Ruddlesden–Popper Planar Faults
Payal Bhattacharya, Maria V. Morrell, Yangchuan Xing, Cherian J. Mathai, Ping Yu, S. Guha
Abstract
Lead halide perovskites provide a test bed for exploring nonlinear optical properties. Although the underlying centrosymmetric crystal structure of 3D lead halide perovskites precludes the phenomenon of second harmonic generation, the third and higher-order harmonic generation are allowed. In this work, we probe the third harmonic generation (THG) from CsPbBr3 nanocrystals (NCs) and compare it to the THG from CsPbBr3 NCs with Ruddlesden–Popper planar faults (RP-CsPbBr3), formed via postsynthetic fusion-growth. The THG from CsPbBr3 NCs is negligible compared with that of RP-CsPbBr3 NCs within a wide range of femtosecond excitation wavelengths. We further compare the THG from a thin film of RP-CsPbBr3 with that of a single crystal of methylammonium lead bromide (MAPbBr3). The THG efficiency of RP-CsPbBr3 is found to be three times greater than that of MAPbBr3. An effective third-order susceptibility of the order of 10–18 m2 V–2 is obtained for a RP-CsPbBr3 film, opening up the prospect of inorganic halide perovskite NCs with planar defects for a range of nonlinear optical applications.