Poly(vinylpyrrolidone) supported copper nanoclusters : glutathione enhanced blue photoluminescence for application in phosphor converted light emitting devices

Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(II) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92.