Stable Lead-Free Blue-Emitting Cs3Cu2Br5 Single Crystal with Self-Trap Exciton Emission for Optoelectronics

Owing to their excellent photoelectric properties, perovskite materials have broad application prospects; however, the toxicity of Pb limits the application of Pbbased perovskite materials. To overcome this problem, Pb-free perovskite materials are prepared by replacing Pb with nontoxic elements including Ge and Sn; nevertheless, the stabilities of these materials are low. Herein, single crystals of nontoxic Cu(I)-based ternary metal halide (Cs3Cu2Br5) with outstanding stabilities and self-trapped excition (STE) emission are constructed by an antisolvent method for the first time; these crystals exhibit central blue emission at 458 nm and large Stokes shifts. Photoluminescence (PL) intensities of the single crystals remain above 96.9% of their initial intensities when these crystals are exposed to an atmospheric environment for 90 days. Moreover, the stabilities of the Cs3Cu2Br5 single crystals are investigated by temperature-dependent PL spectroscopy, which suggests a considerable exciton binding energy of 503 meV, and derivative thermogravimetric analysis, which indicate that the temperature of complete decomposition of Cs3Cu2Br5 is above 930 degrees C. Furthermore, a new class of white light-emitting diodes with an ultrahigh color rendering index of 97.8 and satisfactory performance is produced using the Cs3Cu2Br5 single crystals. The study demonstrates significant potentials of Cu(I)-based single crystals in the field of optoelectronics.

Automated summary

Nontoxic Cu(I)-based ternary metal halide (Cs3Cu2Br5) single crystals with outstanding stabilities and self-trapped exciton (STE) emission are prepared for the first time by an antisolvent method. These crystals exhibit central blue emission and large Stokes shifts. The study demonstrates significant potentials of Cu(I)-based single crystals in the field of optoelectronics.