Air-grown hybrid copper(i) halide single crystals: structural transformations and ultraviolet-pumped photoluminescence applications

Abstract

Lead-free copper-based halide hybrid materials have emerged as a class of potential candidates for next-generation optoelectronic devices. In this work, we demonstrated that Gua₄Cu₄Br₈ and Gua₃Cu₂I₅ (Gua = CH₆N₃⁺) single crystals have been successfully grown by slow evaporation methods in an ambient atmosphere. Interestingly, non-centrosymmetric Gua₆Cu₄I₁₀ single crystals were formed on the basis of Gua₃Cu₂I₅ induced by chiral (R)- and (S)-methylbenzylamine (MBA) cations. In particular, Gua₃Cu₂I₅ exhibited a large Stokes shift of about 200 nm with a long PL lifetime of about 3835 ns and an absolute PLQY of about 72.04% at room temperature. More importantly, ultraviolet (UV)-pumped light-emitting diodes based on Gua₃Cu₂I₅ single crystals exhibited strong photoluminescence characteristics at an emission peaking position of about 575 nm with high luminance. The above characteristics should provide guidance for further applications of lead-free hybrid single-crystalline optoelectronic devices.