Broadband blue light emissions of one-dimensional hybrid Cu(i) halides with ultrahigh anti -water stability

Low-dimensional organic-inorganic hybrid lead halide perovskites have attracted much interest in solid-state lighting and displays, but the toxicity and instability of lead halide are obstacles to their industrial applications, which must be overcome. As an alternative, Cu(I)-based hybrid metal halides have emerged as a new type of luminescent material owing to their diversified structure, adjustable luminescence, low toxicity and low cost. Herein, we report three one-dimensional (1D) hybrid Cu(I)-based halides with the general formula ACu₂Br₄ (A = [(Me)₄-Pipz]²⁺ and [BuDA]²⁺ and [TMEDA]²⁺). These 1D hybrid Cu(I) halides display stable broadband blue emission with maximum emission peaks in the range of 445-474 nm and the highest photoluminescence quantum yield of 37.8%. Furthermore, in-depth experimental and theoretical investigations revealed that the broadband blue emissions originate from the radiative recombination of self-trapped excitons. Most importantly, there is no structural degradation and attenuation of emission intensity even after continuously soaking these halides in water for at least two months, demonstrating their ultra-high anti-water stability. Hirshfeld surface analysis shows that a large number of weak hydrogen bonds can protect the inorganic skeleton from degradation due to water. This work provides a new strategy for the design of water-stable Cu(I)-based halides with efficient blue emission and wide potential applications in humid environments.