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

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 Gua(4)Cu(4)Br(8) and Gua(3)Cu(2)I(5) (Gua = CH6N3+) single crystals have been successfully grown by slow evaporation methods in an ambient atmosphere. Interestingly, non-centrosymmetric Gua(6)Cu(4)I(10) single crystals were formed on the basis of Gua(3)Cu(2)I(5) induced by chiral (R)- and (S)-methylbenzylamine (MBA) cations. In particular, Gua(3)Cu(2)I(5) 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 Gua(3)Cu(2)I(5) 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.