Fabrication of high color rendering index white LED using Cd-free wavelength tunable Zn doped CuInS₂ nanocrystals

Highly luminescent Cd-free Zn doped CuInS₂ nanocrystals (ZCIS NCs) were synthesized, and their properties were evaluated using Xray diffraction, Raman, UV, and photoluminescence. The crystal structure of the ZCIS NCs was similar to the zinc blende, and the lattice constant decreased with increasing Zn concentration. By incorporation of Zn, the emission wavelength was tuned from 536 to 637nm with concomitant enhancement of the quantum yield up to 45%. A white light emitting diodes, integrating dual ZCIS NCs (λ_em = 567, and 617nm) and a 460nm InGaN LED, exhibited a high color rendering index of 84.1 with a warm color temperature of 4256.2K. The CIE-1931 chromaticity coordinates were slightly shifted from (0.3626, 0.3378) at 20mA to (0.3480, 0.3206) at 50mA.