Exciton tunneling behaviors in two dimensional halide perovskite

Two-dimensional (2D) halide perovskite materials have attracted great attention because of their impressive optoelectronic properties in light-emitting diodes (LED), sensors and solar cells, etc. Recently, it has been shown that the low dimensional perovskites with direct white light emission may act as the single component phosphors in next generation white-LEDs. Here, we demonstrate the temperature dependent photoluminescence (PL) properties of white light 2D perovskites by laser excitation. Spectroscopic measurements suggest that the white light spectrum consist of free exciton (FE) and self-trapped exciton (STE). The relative intensities between the FE and STE are temperature dependent, and the energy tunneling effect is dominated at low temperature while the thermal quenching is responsible for the higher temperature region. Our results give the physical insight of the energy transfer and thermal behaviours of the excitons in 2D perovskites.