Brownish red emitting YAG:Ce3+,Cu+ phosphors for enhancing the color rendering index of white LEDs

The optical properties of Cu+ and Ce3+ co-doped Y3Al5O12 synthesized by co-precipitation method are investigated in detail. Doping Cu+ ion into the YAG has little effect on the crystallized structure but the energy levels of Ce3+ ions have been changed. After doping with Cu+, the intensity of the broad emission band in the range of 580–700 nm has been enhanced under the visible region excitation light (400–500 nm) compared with that of undoped sample. Two broad emission bands of the electroluminescence spectra centered at around 540 nm (yellow) and 630 nm (red) are observed via a downconversion process under blue light (λem = 460 nm) excitation. Meanwhile, the red region of the electroluminescence spectra has been enlarged. Hence, Cu+ doping could be an effective method to enhance the red light proportion in white LEDs.

► Under the excitation of blue GaN chips, YAG:Ce3+,Cu+ phosphors exhibit brownish red.
► The peak of electroluminescence spectrum of YAG:Ce3+ developed into two peaks via doping Cu+ into the phosphors.
► We greatly improve the proportion of white LED light color.