Synthesis and application of non-toxic ZnCuInS₂ZnS nanocrystals for white LED by hybridization with conjugated polymer

In this study, strongly luminescent non-toxic CuInS₂-ZnS (ZCIS) alloy nanocrystals were synthesized using inorganic precursors and noncoordinating solvents. The emission wavelength was tuned from 575 nm to 655 nm by introducing the different ratios of Zn doped into a CuInS₂ lattice. A further blue shift was observed by overcoating the ZnS shell and the quantum yield also increased to 46. The white LED was generated by combining a 430 nm LED chip with a greenish-yellow emission poly (9,9-dioctyl-2,7- divinylenefluorenylene)-alt-co-(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene) conjugated polymer and 640 nm deep red emission ZnCuInS₂ZnS nanocrystals. Through a partial energy transfer between the polymer and nanocrystals, the emission intensity of the nanocrystals was enhanced and the fabricated white LED covered the whole visible spectral region. The white LED produced warm white light (3237.4 K) with a high color rendering index of 83.8. The CIE chromaticity coordinates slightly varied from (0.3891, 0.3357) at 20 mA to (0.3843, 0.3398) at 60 mA.