Optimal spectra of white light-emitting diodes using quantum dot nanophosphors.

The relationship and trade-offs between the performance parameters including color rendering index (CRI), luminous efficacy of radiation (LER) and correlated color temperature (CCT) of white LEDs using quantum dot nanophosphors (QD-WLEDs) are investigated for CRI ≥ 80 and LER ≥ 300 lm/W at 1500 K ≤ CCT ≤ 6500 K. The optimal spectra of QD-WLEDs with CCTs of 2700-6500 K have been obtained with a nonlinear program for maximizing LER under conditions of both CRI and a special CRI of R9 strong red above 90 or 95. Furthermore, high performance QD-WLEDs with LER = 381 lm/W for CRI = R9 = 90 and LER = 371 lm/W for CRI = R9 = 95 at CCT = 3000 K, with LER = 361 lm/W for CRI = R9 = 90 and LER = 352 lm/W for CRI = R9 = 95 at CCT = 4500 K, and with LER = 346 lm/W for CRI = R9 = 90 and LER = 338 lm/W for CRI = R9 = 95 at CCT = 5700 K could be achieved. The LERs of high performance white LEDs using QD nanophosphors increase by 13% to 32% compared with that of white LEDs using traditional phosphors.