Growth and Optical Properties of Yellow Luminescent [Epy]2[CuBr3] Single Crystals Based on Self Trapping States

The low-dimensional organic-inorganic lead halide compound has garnered significant attention in recent times due to its exceptional optoelectronic properties. However, its application in the field of optoelectronics has been hindered by the toxicity of lead. Here, a novel inorganic-organic compound [Epy]₂[CuBr₃] single crystal material with a 0D structure based on Cu(I) is introduced. The single crystal exhibits a broad band yellow luminescence, a significant Stokes shift, and a microsecond-scale photoluminescence (PL) lifetime, which is mainly attributed to the self-trapped excitons (STEs) excitation. In addition, the relevant PL spectra are measured at 78–348 K. The photoluminescence intensity decreases with increasing temperature due to strong electro-phonon coupling. The exciton binding energy E_b of the crystal is 76.43 meV, and the Huang-Rhys factor S is 40.55. It is worth noting that the crystal also shows a good response to X-rays. Overall, [Epy]₂[CuBr₃] displays its good potential.