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122 results on '"Li, Zong-Tao"'

7. Utilizing Photothermal Actuation Structure to Improving Light Extraction Efficiency and Ambient Contrast Ratio of Light-Emitting Diode Display Devices

Author

Yu, Binhai, Meng, Jiahao, Li, Jiasheng, Wu, Junhao, Ding, Xinrui, and Li, Zong-Tao

Abstract

Light-emitting diode (LED) display devices that combine high light extraction efficiency (LEE) and high ambient contrast ratio (ACR) are the key to achieve high-performance displays. At present, the industry usually can only meet one performance at the expense of the other. In this article, a simple optical performance regulation method that does not require additional energy drive was implemented, by integrating photothermal actuation structure (PAS) into LED display devices to improve their LEE and ACR. Specifically, a PAS based on graphene oxide (GO) and polydimethylsiloxane (PDMS) (GO-PDMS PAS) was designed. The GO layer plays a role in extinction, which can reduce the reflectivity of LED display devices, thereby improving ACR. The PDMS layer and the GO layer jointly play a role in photothermal deformation; by absorbing the optical energy of LED display devices, the GO-PDMS PAS gradually opens, improving the LEE. Compared with the commercial LED display device using the graphite as extinction layer (GPH-LED), the ACR and LEE of the LED display device using the GO-PDMS PAS as extinction layer (PAS-LED) were improved by 437% and 150%, respectively. In the future, scholars can further study and optimize the structure of the PAS and design it in combination with other functional materials, thereby further improving the LEE and ACR of LED display devices.

Published
2024
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11. Preparation of Dome-Shaped SiO2/Al2O3 Composite-Patterned Sapphire Substrate for High-Performance Mini-LED Backlight Modules

Author

Xu, Liang, Meng, Jiahao, Yang, Zhihui, Li, Jiasheng, Ding, Xinrui, and Li, Zong-Tao

Abstract

High-efficiency mini-LED with a large light-emitting angle is the key to achieving high-quality high dynamic range (HDR) in liquid crystal display (LCD) displays. In this study, we adopted photolithography and ion beam-assisted electron beam evaporation to prepare a dome-shaped SiO2/Al2O3 composite-patterned sapphire substrate (CPSS). Simultaneously, inductively coupled plasma (ICP) dry etching was used to form a patterned sapphire substrate (PSS) as the contrast group. Combined with epitaxial growth and chip manufacturing processes, mini-LED flip chips prepared using CPSS and PSS were obtained, and mini-LED backlight modules were prepared. By comparison, we found that the CPSS-LED chip has higher external quantum efficiency (EQE), and higher EQE brings higher peak brightness, which improves the HDR performance. Simultaneously, we also found that the CPSS-LED chip has a larger light-emitting angle, and the mini-LED backlight module made of it shows a more uniform irradiance distribution and better light mixing effect. In short, we prepared a high-performance mini-LED backlight module using the CPSS-LED chip with both a large light-emitting angle and high EQE, which is expected to be used in future LCD displays.

Published
2023
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32. Improving Ambient Contrast Ratio of Display Device at Oblique Angle Using a Fe3O4-Magnetic Particle Chained Pillar Array Structure

Author

Li, Zong-Tao, Wu, Jun-Hao, Liang, Guan-Wei, Yang, Ren-peng, Yang, Zhihui, and Li, Jia-Sheng

Abstract

A high ambient contrast ratio (ACR) is essential for achieving a high dynamic range in advanced display applications, but reported ACR enhancement strategies always result in reduced optical efficiency of light-emitting diode (LED) display devices. In this study, an Fe3O4-magnetic particle-chained pillar array (Fe3O4-MPCP) structure was introduced to improve the ACR of LED display devices with low optical loss. The results indicated that the MPCP structure achieved high ACR at an oblique angle using surface pillar array to suppress ambient light reflections, and its internal magnetic particle chain improved the transmissivity to maintain high device efficiency. Compared with the commercial graphite-coated device at typical viewing angles (i.e., 0 deg and 60 deg), the ACR of the optimal MPCP device increased by 217 and 140%, while the device efficiency increased by 25 and 12%, respectively. Therefore, the proposed method provides a novel approach for significantly improving ACR at all oblique angles while maintaining high device efficiency, which can be easily integrated into various LED display devices and has significant potential in advanced display applications.

Published
2024
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