Mechanochemical Synthesis of Phase-Pure CsCu2I3 and Cs3Cu2I5 Phosphors Regulated by Polar Solvents and Their Application in Tunable Chromaticity LEDs

Lead halide perovskites have garnered interest in light-emitting diode (LED) applications due to their strong emission and tunable properties. However, conventional synthesis methods involve energy-intensive thermal processes and hazardous organic solvents, raising environmental concerns. In this study, we report a simple and eco-friendly mechanochemical approach that produces phase-pure blue-emitting Cs 3 Cu 2 I 5 (emission at 440 nm) and yellow-emitting CsCu 2 I 3 (emission at 570 nm) phosphors through polarity modulation and control of grinding duration. Our comprehensive analysis of the phase transitions during mechanochemical synthesis reveals that pure Cs 3 Cu 2 I 5 was synthesized from a 3:2 precursor molar ratio in ethanol for 30 min, while pure CsCu 2 I 3 was obtained from a 1:2 precursor molar ratio in an aqueous solution for 7.5 min. Moreover, Raman spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy analyses confirmed that phase-pure phosphors were achieved through these methods. Finally, we fabricated a series of color-adjustable LEDs by mixing Cs 3 Cu 2 I 5 and CsCu 2 I 3 phosphors in different proportions. This demonstrates the potential of our mechanochemical synthesis for the efficient, large-scale production of next-generation lighting materials with tunable emission.