Quantum dot enabled efficient white leds for wide color gamut displays

Abstract

In recent years quantum dots (QDs) emerge as a powerful building block for liquid-crystal display (LCD) technology, and they are successfully used in the form of color enhancement films. However, their transition toward efficient and wide color gamut LEDs for backlighting remain as an important challenge, which can decrease the required amount of QDs per TV for orders of magnitude. Here, QD-based white LEDs are reported that can simultaneously operate with a high external quantum efficiency (EQE) of 39.8% and a wide NTSC color gamut coverage of 133.3%. For red-emitting spectral range, giant CdSe/CdS core/shell QDs are synthesized via hot injection method, and it is observed that 20 monolayers of CdS shell can lead to a near-unity photoluminescence quantum yield (PLQY) of 98%. In addition, green-emitting CdZnSeS/ZnS alloyed core/shell QDs show a PLQY of 97% with a narrow full width at half maximum (FWHM) of 20 nm. To maintain the optical properties of QDs in device architecture, QDs are injected in liquid matrix on blue LED chips and used as the backlighting source for LCD TV that lead to bright and vivid colored images. QD-based white LEDs with high efficiency and wide color gamut have significant potential for next-generation display technology.