Optical properties of two-dimensional perovskite single crystal of (C6H5C2H4NH3)2PbI4

2D perovskite materials have exhibited remarkable stability under ambient conditions, making them highly desirable semiconductors for optoelectronic applications. However, there has been limited research conducted on the optical properties of 2D perovskite single crystals. In this study, we employed temperature dependence and excitation intensity dependence photoluminescence (PL) spectroscopies to investigate the optical properties of (PEA)2PbI4 (PEPI) single crystals. The PL spectrum of the PEPI single crystal reveals a dual emission consisting of narrow emission (NE) and board emission (BE), which will vary with temperature. NE demonstrates a nearly linear relationship between PL intensity and low excitation power, suggesting the dominance of excitons in the photophysical properties. Conversely, BE displays a superlinear relationship, indicating the presence of free carriers and/or trapped carriers. Furthermore, micro-area spectral scanning of the PEPI single crystal reveals the presence of multiple layers, with numerous small grains visible on the surface. The Full Width at Half Maximum (FWHM) at the boundaries is larger, and the peak energy is lower compared to other locations. Mechanical exfoliation of the crystal reduces the presence of small grains on the surface, but does not alter the layer-to-layer boundary.