Bright luminescence of new low-melting copper(i) chlorides with compact organic cations

Abstract

Hybrid copper(I) halides are nowadays the subject of intensive studies as promising materials for various optoelectronic applications. This class of materials is characterized by wide structural diversity enabled by a great variety in the size and shape of organic cations. Therefore, the search and analysis of composition–structure–property relationships is a key step for the rational design of new hybrid halide materials with desired properties. In this paper, we comprehensively studied two ACl/CuCl systems with dimethylammonium (DMA⁺) and acetamidinium (Ac⁺) organic cations and proved the formation of five new crystalline phases: DMACu₂Cl₃, DMACuCl₂, DMA₄[Cu₂Cl₆], DMA₃CuCl₄, and AcCuCl₂. Based on X-ray diffraction and Raman spectroscopy, the discovered phases are characterized by a reduced dimensionality of inorganic sublattice (1D or 0D) and loosely packed crystal structure. Depending on the structure, these phases demonstrate photoluminescence in the range from red to blue (at room temperature and at 77 K), and “0D” phases show a high quantum yield up to 80%. Additionally, the studied hybrid chlorocuprates with compact organic cations were found to have melt without decomposition at relatively low temperatures (from 32 to 120 °C), which provides prospects for potentially useful low-temperature facile processing of novel efficient light-emitting materials.