Polymer‐Encapsulated Halide Perovskite Color Converters to Overcome Blue Overshoot and Cyan Gap of White Light‐Emitting Diodes

Abstract Currently, the most popular way to manufacture white light‐emitting diodes (WLEDs) is based on blue‐emitting InGaN LED chips (440–460 nm) and yellow‐emitting phosphor coating (520–700 nm) to produce white light lighting. However, because conventional white WLEDs lack the uniformly distributed continuous emission spectrum compared to natural sunlight: “blue overshoot” (extra 440–460 nm blue‐light can cause damage to the retina) and “cyan gap” (470–520 nm wavelength range). Here, a novel strategy to “kill two birds with one stone” is reported: using the stable and bright polymer encapsulated perovskite nanocrystals (PNCs) composite films as the cyan color converters that efficiently absorb the “blue overshoot” and effectively emit the cyan light to fill the “cyan gap”. A series of polymer‐encapsulated PNC films is achieved that can reach very high photoluminescence quantum yield (PL QY) of 90–95% under 450 nm blue‐light excitation. Importantly, both 370 nm UV‐excited WLED and 455 nm blue‐excited WLED devices are constructed that exhibit smoothly and evenly distributed white light without blue overshoot and cyan gap, which was not achieved before for blue‐excited cyan‐emissive materials. This study paves the way toward the application of PNC color converters in the next generation full‐visible‐spectrum WLED lighting that mimic the natural daylight.