Color-enrichment semiconductor nanocrystals for biorhythm-friendly backlighting
Demir, Hilmi Volkan
Zeitschrift fur Physikalische Chemie
1457 - 1468
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Nanocrystals (NCs) offer great opportunities for developing novel light-emitting devices possessing superior properties such as high quality indoor lighting, efficient outdoor lighting, and display backlighting with increased color definition. The narrow-band emission spectra of these materials also offer opportunities to protect the human daily biological rhythm against the adverse effects of display backlighting. For this purpose, here we address this problem using color converting NCs and analyzed the effect of the NC integrated color converting light-emitting diode (NC LED) backlight spectra on the human circadian rhythm. We employed the three existing models including the circadian light, the melanopic sensitivity function, and the circadian effect factor by simultaneously satisfying the National Television Standards Committee (NTSC) requirements. The results show that NC LED backlighting exhibits (i) 33% less disruption on the circadian cycle if the same color gamut of the commercially available YAG:Ce LED is targeted and (ii) 34% wider color gamut while causing 4.1% weaker disruption on the circadian rhythm compared to YAG:Ce LED backlight if the NTSC color gamut is fully reproduced. Furthermore, we found out that blue and green emission peaks have to be located at 465 with 30 nm bandwidth and at 535 nm with 20 nm bandwidth, respectively, for a circadian rhythm friendly design while the red component offers flexibility around the peak emission wavelength at 636 nm as opposed to the requirements of quality indoor lighting. These design considerations introduced as a new design perspective for the displays of future will help avoiding the disruption of the human circadian rhythm.