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

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.