Direct synthesis of high quantum yield lead‐free CsCu2I3 powder in water and its application in yellow LED

Abstract Yellow light‐emitting diodes (LEDs) with a wavelength of 570–590 nm can reduce the excitability of peripheral nerves and the sensitivity of the skin, stimulate collagen synthesis, and tighten the skin, which plays an important role in skin rejuvenation. In general, commercial LEDs are made of phosphor excited by ultraviolet chips. It is very important for the development of yellow light emitters with high luminous efficiency, good stability, and environmental protection. For the first time, a simple organic structural unit (2‐methylimidazole, 2‐MIM) was used to collect a mixture of two metal precursors (CsI and CuI) and successfully synthesized an all‐inorganic lead‐free yellow light CsCu 2 I 3 powder in water. The prepared CsCu 2 I 3 powder exhibited excellent optical properties and considerable stability. Finally, a phosphor‐converted LED (pc‐LED) device was fabricated via the CsCu 2 I 3 phosphor coated on a 310 nm ultraviolet chip. The pc‐LED device's electroluminescence spectra may be a good fit for the blood's absorption regions. Therefore, this work provides a facile method for the synthesis of novel lead‐free metal halide CsCu 2 I 3 powder in eco‐friendly solvents. In addition, the stable and efficient CsCu 2 I 3 powder shows promising exciting potential applications in photoluminescence and phototherapy fields.