Studies of Scotopic/Photopic Ratios for Color-Tunable White Light-Emitting Diodes

Three- and four-hump InGaN-based white light-emitting diodes (LEDs) have been computationally investigated. The investigation includes three-hump LEDs precoated with green- and red-emitting quantum dots (QDs) and four-hump LEDs precoated with green-, yellow-, and red-emitting QDs. Results show scotopic/photopic (S/P) ratios 3.80 and color rendering indices (CRIs) ≥ 70 for three-hump LEDs and S/P ratios 3.90 and CRIs ≥ 70 for four-hump LEDs under a correlated color temperature (CCT) of 45 000 K. Furthermore, for both three- and four-hump LEDs under the condition of CCT 5000 K, optimal results in this paper exhibit capabilities of exceeding S/P = 2.50 and simultaneously satisfying the criterion of CRI ≥ 70. Our simulation procedure is conducted under variations of nine CCTs, several wavelengths, and peak heights. Optimized results of S/P ratios and CRIs are identified and retained through filtering off a great number of unqualified candidates. Finally, present findings may help improve the quality of eye visions pertaining to LED illumination and help reduce the electrical energy consumption related to LED usage.