High Color Gamut Mini-LED Backlight Demon based on Dual-Emissive Perovskite Quantum Dots Films

Here, we highlight the up-to-date PODF with low cost, high brightness and low heavy metal content. This technology originated invented by our group at Beijing Institute of Technology (BIT)and jointly developed by Zhijing NanotechCo., Ltd. and Hefei Lucky Co., Ltd.. The green emissive PQDF is now commercial available from Zhijing Nanotech Co., Ltd. For this demon, the green and red PODF were fabricated through our reported in situ fabrication process. The fabrication involves three stages. Firstly, the raw materials of perovskites and polymer were mixed in N, N-dimethylformamide (DMF) to form the precursor solution, Secondly, the precursor solution was coating onto PET film to obtain a uniform precursor coating layer. Thirdly, with the evaporation of solvent under vacuum drying, the PQDF with strong PL emission were formed on the polymer substrate.

Figure la and b shows PL spectra of green and red emissive PODF, respectively. The PL emission peaks of these green and red films locate at 530 nm and 628 nm, with FWHM of 2l nm and31 nm for green and red PQDFs, respectively. Figure le presents the transparency properties of the green and red composite films.The transparency of these films approach to 92%.

To illustrate the potential use of these PODF films in LCD backlight, we prepared green and red emissive PQDF with width about 40 cm and length about 300 cm by adapting our reported in-situ fabrication methods. As shown in Figure 2a and b, these films are uniform with strong PL emission. The green and red films were assembled into a composite dual emissive film for Mini-LED application. Figure 2c shows a schematic diagram of the configuration of the integration. Figure 2 d shows the electroluminescence (EL)spectra of the backlight used Mini LED and PODF. The peak position and FWHM were kept after combination. The transparency was slightly reduced to 90%. The quantum yield of the POD based color convention film is about84%. The decrease of PLOYs can be attributed to the reabsorptionof green light by red film. Figure 2e shown CIE color coordinates corresponding to the dual emissive PODF combined with blue Mini-LED backlight and NTSC standard. The color coordinates area of the composite film and blue Mini LED chip is much larger than that of the color space of the NTSC(~118% ofNTSC 1931)standard with a matching rate of 100%. The excellent opticalproperties make them very suitable for LCD backlight display application. We then developed a 32 inch LCD demo, an enhanced performance can be visualized. As shown in figure 2fthe screen using dual emissive perovskite quantum dots composite film assembly backlight unit gives more details of object colors.The demo screen demonstrates a higher saturation and a more remarkable color rendition.