Pressure-induced emission of cesium lead halide perovskite nanocrystals

Abstract

Metal halide perovskites (MHPs) are of great interest for optoelectronics because of their high quantum efficiency in solar cells and light-emitting devices. However, exploring an effective strategy to further improve their optical activities remains a considerable challenge. Here, we report that nanocrystals (NCs) of the initially nonfluorescent zero-dimensional (0D) cesium lead halide perovskite Cs ₄PbBr ₆ exhibit a distinct emission under a high pressure of 3.01 GPa. Subsequently, the emission intensity of Cs ₄PbBr ₆ NCs experiences a significant increase upon further compression. Joint experimental and theoretical analyses indicate that such pressure-induced emission (PIE) may be ascribed to the enhanced optical activity and the increased binding energy of self-trapped excitons upon compression. This phenomenon is a result of the large distortion of [PbBr ₆] ⁴⁻ octahedral motifs resulting from a structural phase transition. Our findings demonstrate that high pressure can be a robust tool to boost the photoluminescence efficiency and provide insights into the relationship between the structure and optical properties of 0D MHPs under extreme conditions.

Abstract

The potential optoelectronic applications of metal halide perovskites make exploration and tuning of their optical properties of great interest. Here the authors show that non-emitting zero-dimensional cesium lead halide perovskites become strongly fluorescent under high pressure, due to distortion-induced effects.