Study of Perovskite QD Down-Converted LEDs and Six-Color White LEDs for Future Displays with Excellent Color Performance

Abstract

A narrow-emitting red, green, and blue (RGB) perovskite quantum dot (PeQD)-based tricolored display system can widen the color gamut over the National Television System Committee (NTSC) to 120%, but this value is misleading with regard to the color perception of cyan and yellow reproduced in the narrow RGB spectra. We propose that a PeQD-based six-color display system can reproduce true-to-life spectral distributions with high fidelity, widen the color gamut, and close the cyan and yellow gap in the RGB tricolored display by adding cyan (Cy), yellowish green (Yg), and orange colors (Or). In this study, we demonstrated pure-colored CsPbX3 (X = Cl, Br, I, or their halide mixtures; Cl/Br and Br/I) PeQD-based monochromatic down-converted light-emitting diodes (DC-LED) for the first time, and we incorporated PeQDs with UV-curable binders and long-wavelength-pass-dichroic filters (LPDFs). CsPbX3 PeQD-based pure Cy-, G-, Yg-, Or-, R-emitting monochromatic DC-LED provide luminous efficacy (LE) values of 81, 184, 79, 80, and 35 lm/W, respectively, at 20 mA. We also confirmed the suitability and the possibility of access to future color-by-blue backlights for field-sequential-color liquid crystal displays, using six-color multipackage white LEDs, as well as future six-colored light-emitting devices with high vision and color performance. The fabricated six-color multipackage white LEDs exhibited an appropriate LE (62 lm/W at total 120 mA), excellent color qualities (color rendering index (CRI) = 96, special CRI for red (R9) = 97) at a correlated color temperature (CCT) of 6500 K, and a wide color gamut covering the NTSC up to 145% in the 1931 Commission International de l'Eclairage (CIE) color coordinates space.

Circadian-tunable Perovskite Quantum Dot-based Down-Converted Multi-Package White LED with a Color Fidelity Index over 90

“…Here, the PL colors of the PeQDs can be blue-shifted by widening the bandgap through the formation of an alloy with smaller anions, decreasing both the unit cell and the covalency of the PeQDs. As we reported previously 17–19 , six selected colors of fully down-converted LEDs were fabricated by capping a LPDF-capped LED package filled with PeQD/NOA 63 paste. As shown in Fig.…”

“…Recently developed perovskite (Pe) QDs as well as Cd-containing II-VI QDs are excellent candidates for tunable multi-package WLEDs 13–17 . Instead of using environmentally harmful, recently commercialized Cd-containing II-VI QDs, the PeQD family is becoming more popular as a less environmentally harmful and excellent candidate for maximizing the circadian tunable range and two-measure system of color quality levels.…”

“…Furthermore, it is necessary to analyze how an efficient LER value, a tunable CER range, a high R f score exceeding 90, and an R g score close to 100 can be obtained from multi-package WLEDs incorporating tunable PeQDs while optimizing the number of mixed monochromatic colors from three to six DC-LEDs (one blue-chip LED plus two or two more fully converted QD-LEDs). In this study, we synthesized six different colors (cyan (C), green (G), yellowish green (Y), amber (A), orange (O) and red (R)) of CsPb(Br 1−x , X x ) 3 (X = Cl, Br) PeQDs using a hot-injection method developed in our previous study 17 and fabricated five PeQD-based CGYOR-emitting monochromatic DC-LEDs and a multi-package WLED based on them with a blue (B)-chip LED. We analyzed and optimized the SPDs of tunable multi-package WLEDs in terms of energy savings, color reproducibility and health benefits.…”

Atomic Characterization of Byproduct Nanoparticles on Cesium Lead Halide Nanocrystals Using High-Resolution Scanning Transmission Electron Microscopy

“…In the family of LHP materials, colloidal all-inorganic cesium lead halide (CsPbX 3 , X = Cl, Br, and I) perovskite nanocrystals combine both high stability and superior high luminescent efficiency compared to their organic-inorganic counterparts [18,19]. With their colloidal properties, many works have concentrated on applying them to solution-processed devices such as display screens [20], lasers [12] and LEDs [8].…”

Cesium lead halide ( CsPbX 3, X = Cl , Br, I) perovskite quantum dots-synthesis, properties, and applications: a review of their present status

“…On the other hand, the application of CsLHQDs has been found to be useful in display-related devices such as LEDs, and impressive progress has been made in this direction. 94,95 Song et al 80 fabricated the first quantum dot light emitting diode (QLED) based on CsPbX 3 QDs with the device configuration ITO/PEDOT: PSS/PVK/QDs/TPBi/LiF&Al. The authors observed luminances (i.e., the intensity of light emitted from a surface per unit area in a given direction) of 742, 946, and 528 cd m −2 (cd ¼ candela) with external quantum efficiency (EQE) values 0.07%, 0.12%, and 0.09% for the blue, green, and orange LEDs.…”