Isoreticular Postsynthetic Modification of Robust Organocopper(I) Halide Hybrids for Enhanced Broad-Band Emission and Turn-On NH3 Sensing

Organometal halide hybrids are an emerging class of single-component white-light emitters originating from self-trapped excitons (STEs), showing many promising attributes such as intrinsic nature and a high color-rendering index (CRI). However, one challenge is to develop rational synthetic strategies to tune the photoluminescence properties on a molecular level. Herein, for the first time, we report the isostructural postsynthetic incorporation of NH3 into organometal halide crystalline materials to enhance the STE-based warm white-light emission, affording substantially increased photoluminescence quantum yields (PLQYs) from 5–5.5 to 60–75%. The NH3-incorporated CuI–halide hybrids are rare examples of lead-free single-component yellowish white-light emitters with high PLQYs and a high CRI of 64–72. The single-crystal-to-single-crystal transformation is monitored by X-ray crystallography and density functional theory calculations, suggesting that the incoming NH3 molecules serve as spacers to isolate linear CuI–halide species at the excited state to facilitate the exciton confinement. Moreover, the precise modification process is highly reversible and selective over many common gaseous molecules or other amines. The organocopper(I) halide hybrids also feature high structural and emissive stabilities for at least 18 months in air at room temperature, affording a high potential for commercial uses in solid-state lighting. This study demonstrates a potentially general strategy to enhance the STE emission on the molecular level.