Highly efficient wide-color-gamut QD-emissive LCDs using red and green perovskite core/shell QDs

Liquid crystal displays are widely used in numerous industries especially in electronics and optics. Considering the current trend, the performance of liquid crystal displays will continually grow due to rapid technological advancement. For instance, recently developed quantum dot based liquid crystal displays exhibit enhanced dynamic range, efficiency, and color gamut. Among the available solutions, fully inorganic cesium lead halide perovskite quantum dots have been widely used owing to their excellent properties such as strong light absorption and good wavelength tunability. Together with emerging peripheral technologies, the realization of efficient quantum dots-emissive liquid crystal displays has remained a dream due to the use of inappropriate red, green, blue quantum dots. To this note, researchers have been looking for alternative solutions to address the challenge.

Among the available solutions, stable InP/ZnSeS/ZnS quantum dots have been developed for application in quantum emissive liquid crystal displays. However, synthesis of stable RG/ InP/ZnSeS/ZnS, to realize larger color gamut, is still a major challenge. Alternatively, recently published literature has indicated several technologies like efficient quantum dot patterns and in-cell metal polarizers steered towards the realization of the high-performance emissive liquid crystal displays. Therefore, researchers have identified color mixing with light recycling filters and long-wavelength pass-dichroic filter, backward emission loss and reduction in the cross- talk as a promising solution to achieve the full-color conversion.

Recently, Kookmin University scientists led by Professor Young Rag Do developed efficient red CsPb(Br_0.35I_0.65)₃/CsPb₂­Br₅ and green CsPbBr₃/CsPbBr₅ core/shell perovskite quantum dot with the aim of achieving high-performance wide-color-gamut liquid crystal displays. The work is published in the research journal, Journal of Materials Chemistry C.

In brief, the authors commenced their work by optimizing the reaction parameters and elements composition through the one-step hot injection process. Next, the color purity and amount of light of the front emitting light was improved by using blue-windowing and RG mirroring light-recycling filters at the bottom position and blue-mirroring and RG-windowing long-wavelength pass-dichroic filter at the top position of the quantum dot film. To actualize their study, they performed a case study on the properties and characteristics of the fabricated red and green perovskite quantum dot emissive liquid crystal displays, taking into consideration the enlarged color gamut, photoluminescence efficiency, and backlight efficiency, and compared the results to the previously developed InP quantum dot-emissive liquid crystal display.

The authors observed that both red and green core/shell perovskite quantum dots exhibited enhanced photoluminescence quantum yield standing at 77.4% and 78.9% respectively as well as improved thermal stability, water resistance, and photostability. Consequently, it was noted that a color-by-blue perovskite quantum dot-emissive-liquid crystal display consisting of the red and greed films were 1.74 times wider and 1.94 times higher than the conventional color filter-liquid crystal displays.

The study by Kookmin University researchers proved suitable for the development of efficient and wide-color-gamut perovskite quantum dot-emissive liquid crystal displays. For instance, the overall enhancement efficiency of 4.28 times was obtained as compared to the conventional color filter-based liquid crystal displays. Therefore, the study will pave way for creation of more advanced liquid crystal displays.