Simultaneous Enhancement of Luminescence Performance and Stability of Cs 3 Cu 2 Cl 5 Crystals in a Humid Environment by a Doping Strategy

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Low-dimensional cesium halide copper-based perovskites have attracted tremendous attention due to their advantages in the optoelectronic field. However, intrinsic factors, such as defects on the Cs 3 Cu 2 Cl 5 surface, tremendously restrict their applications in a highly humid environment. In this work, a series of Cs 3 Cu 2 Cl 5 crystals doped with metal ions (Mn 2+, Ni 2+, Li +, and Rb + ) has been prepared to enhance their luminescence performance and stability in a highly humid environment. In particular, the Rb + -doped Cs 3 Cu 2 Cl 5 exhibits excellent luminescence intensity, photoluminescence quantum yield (72.55%), and water stability. The Rb + dopant induces shrinkage of lattice constants, a decreased band gap, and fewer structural defects. The structure of Cs 3 Cu 2 Cl 5 is reinforced by Rb + doping to prevent the inorganic framework from the damage of water molecules. A suitable Huang–Rhys factor contributes to the intense excitation–phonon coupling and reduced electron–phonon coupling. Therefore, the self-trapped excitations (STEs) from the 0D Cs 3 Cu 2 Cl 5 structure contribute to the enhanced luminescence performance and stability in a highly humid environment. The luminescent mechanism is presented to explain how Rb + doping improves the luminescence properties of the Cs 3 Cu 2 Cl 5 crystals. Moreover, the Mn 2+ -, Ni 2+ -, and Li + -doped samples also demonstrate a higher luminescence intensity than that of the pristine Cs 3 Cu 2 Cl 5 . Finally, the practical applications of Rb + -doped Cs 3 Cu 2 Cl 5 crystals are systematically investigated, revealing that the as-synthesized metal-ion-doped inorganic copper-based perovskites may be potentially applied in fields of anticounterfeiting and green LEDs.