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

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.