Pressure enables high-standard white light emission and significant emission enhancement in a 2D halide perovskite

Abstract

Two-dimensional (2D) organic–inorganic halide perovskites (OIHPs) usually show broadband emission characteristics, which are useful for obtaining white light emissions. However, achieving high standard white light emission using a single halide remains challenging under ambient conditions. Here, we report pressure-induced high-standard white light emission and significant emission enhancement of a 2D OIHP, (CHA)₂PbBr₄ (CHA = cyclohexylamine). It was found that (CHA)₂PbBr₄ exhibited significant pressure-induced emission enhancement: a 20- and 3-fold enhancement of the narrow and broadband emissions, respectively, from free excitons and self-trapped excitons. Such a prominent enhancement gives illumination chromaticity coordinates of (0.32, 0.34) at 2.0 GPa, being significantly close to the ideal white light of (0.33, 0.33). Our high-pressure synchrotron powder X-ray diffraction and theoretical calculations reveal that this phenomenon mainly arises from the pressure-induced distortion of the PbBr₆ octahedra. This work opens up possibilities for realizing high-standard white light emission of 2D OIHPs via strain engineering.