Enhancing the Efficiency of Color Conversion Micro-LED Display with a Patterned Cholesteric Liquid Crystal Polymer Film

Abstract

Color-converted micro-light-emitting diode (micro-LED) displays with wide color gamut, high ambient contrast ratio, and fast response time are emerging as a potentially disruptive technology. However, due to limited optical density and thickness of the color-conversion film, the blue light leakage and low color-conversion efficiency still hinder their widespread applications. In this paper, we demonstrate a patterned cholesteric liquid crystal (CLC) polymer film with two special optical functionalities. On the green and red sub-pixels, the corresponding planar CLC texture acts as a distributed Bragg reflector for the blue light, which in turn improves the color conversion efficiency and expands the color gamut. On the blue sub-pixels, the corresponding focal-conic CLC texture acts as light scattering medium, which helps to reduce the angular color shift. Further analysis reveals that the patterned CLC film can alleviate the crosstalk between green and blue color filters. Therefore, compared to the display system without such a CLC film, our proposed device structure increases the color conversion efficiency by 143% (at ~90% Rec. 2020) and reduces average angular color shift Δu’v’ from 0.03 to 0.018 at the viewing angle with the most severe color shift. Such a patterned CLC film is applicable to all kinds of color-conversion display systems, including organic and inorganic phosphors.

Environmental-Friendly Cs3MnxZn(1–x)Br5@PS Films Used for Wide Color Gamut Backlight Displays

“…The absorption coefficient, PLQY, thickness, and green−red ratio of the film all affect the color conversion of LCD devices. 48,49 Moreover, the effects of the Cs 3 Mn 0.6 Zn 0.4 Br 5 @K 2 SiF 6 :Mn 4+ @PS thickness and green−red ratio on the performance of LCD devices were discussed in detail. In this way, a series of films were prepared with different ratios and thicknesses, and the content ratios of Cs 3 Mn 0.6 Zn 0.4 Br 5 and K 2 SiF 6 :Mn 4+ were 1.00:0.005, 1.00:0.010, and 1.00:0.015, respectively.…”

Effective Blue Light-Absorbing AuAg Nanoparticles in InP Quantum Dots-Based Color Conversion

“…In the color-by-blue mode-based display device where QD emitters are placed in the front panel, QDs can be undesirably excited upon exposure to ambient lights [ 31 , 32 ]. This inevitably deteriorates the color purity and contrast ratio of the display device.…”

Luminescent Nanomaterials for Energy-Efficient Display and Healthcare

“…The first approach is the additive optical film. As shown in Figure a, to improve the excitation light absorption, a high-pass filter recycles the blue light leaked from the QDCC back to the film to excite the QD material, and the absorption filters on top of the QDCC prevents blue light leakage and eliminates ambient light excitation. , The band-pass filter can be a distributed Bragg reflector (DBR) or a stacked cholesteric liquid crystal (CLC) film with opposite chirality.…”