Photometric Optimization of Color Temperature Tunable Quantum Dots Converted White LEDs for Excellent Color Rendition

The photometric optimization for maximizing limited luminous efficacy (LLE) of correlated color temperature (CCT) tunable quantum dots (QDs) converted white light-emitting diode (LED) (QD-WLED) with green, yellow, and red QDs excited by a blue chip was developed under the constraints of the designated color rendering index (CRI) and color quality scale (CQS). The results show that CCT tunable (2700-6500 K) QD-WLEDs with both excellent color rendition and high luminous efficacy should use three narrow emission QDs. The optimal CCT tunable QD-WLEDs with CRI ≥ 95 and CQS ≥ 93 consist of a blue chip (461.0, 25 nm) and green (519.7, 30 nm), yellow (569.2, 30 nm), and red (622.9, 30 nm) QDs, and their LLEs could reach 270-292 lm/W. Simulation demonstrates that QD-WLEDs using a blue chip (460.0, 25 nm) and the green (521, 41 nm), yellow (562 nm, 44 nm), and red (620, 59 nm) CdTe QDs could realize CCT tunable white lights with CRIs of 95-96, CQSs of 93-94, and LLEs of 256-272 lm/W, which increase by 12-21%, compared with that of optimal phosphor-coated white LEDs (pc-W LEDs). Finally, LEs of both QD-WLED and pc-W LED were estimated. The requirements of the overall efficiency of QDs film were present if the CCT tunable QD-WLEDs were competitive to the CCT tunable pc-W LEDs.