High-performance, narrow-band green-emitting phosphors for white LEDs: recent advances and perspectives

Abstract

An ultrawide-color-gamut backlight is crucial for achieving ultrahigh definition and ultrahigh resolution liquid crystal displays (LCDs), where green-emitting phosphors with narrow spectral emission are the decisive factors. However, the key green-emitting phosphors currently used in light-emitting diode (LED) backlights, such as commercial β-SiAlON:Eu²⁺, have the disadvantages of a wide emission band and large particles. In order to display more colorful and vivid photographs, there is an urgent need to accelerate the development of narrow-band green-emitting phosphors with independent intellectual property rights and high quantum efficiency. This article outlines the design of green-emitting phosphors and the improvement of their luminescent properties. From a design perspective, an optimal phosphor must consider the host material and the activator. The emission bands of Tb³⁺, Mn²⁺, Ce³⁺ and Eu²⁺ are usually located in the visible region, and the short luminesence decay time of Eu²⁺/Ce³⁺ makes it a potential activator for high-quality displays. In the exploration and selection of hosts for novel phosphors, approaches such as single-particle diagnosis, high-throughput density functional theory (DFT) calculations and mineral-inspired prototype evolution are commonly employed. Thermal stability and quantum efficiency (QE) are critical properties for phosphors, and various strategies to enhance these characteristics are discussed herein. Moreover, the color gamuts of various green-emitting phosphors are presented, highlighting their applications in green-emitting phosphor-based WLEDs used in LCD screens and projectors. These WLEDs display more vivid image quality than the conventional commercial WLEDs. Finally, the future outlook on exploring and developing green-emitting phosphors with enhanced performance is discussed.