Growth and Optical Properties of Cs3Cu2Br5 Single Crystals by Vertical Bridgman Method

In recent years, Copper(I)-based inorganic halides have garnered significant interest for their exceptional optical properties. In this paper, Cs 3 Cu 2 Br 5 single crystals are grown by the vertical Bridgman method, resulting in large transparent single crystals ≈40 mm in length. The crystals are characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). Transmission spectra, photoluminescence (PL), temperature-dependent fluorescence spectra, X-ray excitation spectra, and photoluminescence decay time are also measured. The results indicate that the Cs 3 Cu 2 Br 5 single crystal exhibits good optical transmittance of 85% in the wavelength range of 250–800 nm and a large direct bandgap of 3.85 eV. The Cs 3 Cu 2 Br 5 single crystal displays intense broadband blue luminescence, featuring significant Stokes shifts, a microsecond-long fluorescence lifetime decay, and higher quantum yield, all attributed to self-trapped exciton emission. The temperature-dependent fluorescence spectra of the crystals are measured to analyze the luminescence mechanism. In summary, the research indicates that the Cs 3 Cu 2 Br 5 single crystal has certain potential applications in the field of photodetectors, light-emitting diodes, scintillators, etc.