Comparative Study on Backlighting Unit Using CsPbBr3 Nanocrystals/KSFM Phosphor + Blue LED and Commercial WLED in Liquid Crystal Display

In this study, K 2 SiF 6 :Mn 4+ microcrystals (KSFM) and CsPbBr 3 nanocrystals were synthesized step by step via co-precipitation and ligand-assisted re-precipitation, respectively, and applied onto a backlighting unit (BLU) using an irradiated blue light-emitting diode (LED) source. The radiant flux down-conversion efficiency was 50% (blue to green) for a CsPbBr 3 -embedded poly(methyl methacrylate) plate and 62% (blue to red) for a KSFM-coated chip LED as a phosphor converter. A blue LED/KSFM/CsPbBr 3 BLU was successfully applied onto a liquid crystal display. The real backlight display performance exhibited a bright white emission with a CIE chromaticity coordinate of ( x = 0.29, y = 0.31) and wide color gamut of 84% of Rec. 2020 standard. Compared with a blue LED/YAG:Ce [color rendering index (CRI) ~ 71], it showed a very low CRI of 37 due to its narrow-band emission. Thus, the BLU could be used in special display applications, which require a high color saturation but not the high CRI of white color displays.