Improving the Light Quality of White Light‐Emitting Diodes Using Cellulose Nanocrystal‐Filled Phosphors

Abstract

Light‐emitting diode (LED) lighting delivers better performance and reliability, and substantially lowers the total cost of ownership compared with conventional lighting. The most common white LED is generally produced using a blue LED chip and phosphor combination to generate white light. This type of phosphor‐converted white LED can be a great alternative to the more expensive 3 chip RGB (red, green, blue) LED. Herein, cellulose nanocrystals, a wood‐derived biopolymer, are used with phosphor to improve the uniformity of correlated color temperature (CCT) and luminous flux from the white LED. These nanocrystals can scatter light strongly and for an optimized concentration of nanocrystals, it is found to increase the luminous flux of the white LED by over 30% compared with the reference sample without any nanocrystal. The CCT uniformity is also improved from 173.45 K for the reference sample to 59 K for the optimized sample. The chromaticity coordinates are also studied and found to be shifting toward lower correlated color temperatures with increasing cellulose concentrations. Combining these results with low cost, wide availability, and environmental impact, cellulose nanocrystals can play an important role in the future generation of white LEDs.

Keywords

• cellulose
• correlated color temperature
• light-emitting diodes
• scattering