Optimal ways of colour mixing for high-quality white-light LED sources

Optimization of colour mixing in white-light sources based on light-emitting diodes (LEDs) only and those utilizing partial light conversion by a yellow YAG:Ce3+ phosphor is carried out by simulations. The trade-off between the colour rendering index (CRI) and efficacy of the white-light sources is examined, accounting for the efficiency of electricity-to-light conversion in state-of-the-art LEDs. The asymmetry and widths of the LED emission spectra, as well as the LED efficiencies, are regarded to depend substantially on the peak emission wavelength. The optimization has provided the optimal peak emission wavelengths of individual LEDs and the power fractions of their contribution to the total emission spectra, allowing estimations of the maximum achievable values of the CRI and efficacy for the white-light sources considered. Their comparison enables choosing the most advantageous solutions for producing high-quality white light.