Optical Properties of Two-Dimensional/Three-Dimensional Composite Perovskite Films

Two-dimensional/three-dimensional (2D/3D) composite perovskites (CPs) are extremely promising for their application in optoelectronics. Although understanding the fundamental optical properties of 2D/3D CPs is of great importance for optimizing the performance of optoelectronic devices, relevant studies still remain far from being sufficient. In this work, by using R-methylbenzylammonium (R-MBA) and R-1-(1-naphthyl)-ethylammonium (R-NEA) as the A-site cations, we have synthesized two kinds of 2D/3D CP films, abbreviated as R-MBA- and R-NEA-films, respectively. Impressively, with an increasing temperature from 80 to 300 K, no phase transition or obvious emission shift is observed in both R-MBA- and R-NEA-films, and the latter has stronger electron-phonon coupling strength. Femtosecond transient absorption spectroscopy reveals that the R-NEA-film exhibits faster hot carrier cooling time and shorter biexciton lifetime. This work not only confirms the possibility of regulating the optical properties of 2D/3D CPs by the use of different organic A-site cations but also provides important information for the development of related optoelectronic devices.