Strategies for Enhancement Luminance of Sub‐Micrometer Phosphor: A Sub‐Micrometer Narrow‐Band Red Phosphor with Ultrahigh Thermal Stability

Abstract

AbstractNowadays, phosphors are widely used in high quality white light emitting diodes (W‐LEDs) and display technology. Micro light emitting diode (Micro‐LED) has the advantages of ultrahigh resolution color saturation, while ordinary phosphors are difficult to apply due to their large particle size. As is known to all, once the phosphor particle size is reduced, its luminescence intensity will loser. This paper presents a strategy to improve the luminescence intensity of sub‐micrometer narrow‐band red phosphors. By increasing the doping concentration of rare‐earth ions through total substitution and reducing the nonradiative transition in the cell, ultrahigh concentration doping of sub‐micrometer phosphors is achieved to improve the luminescence intensity. Surprisingly, with increasing Eu3+ up to entirely substitution for Gd3+ site, both the absorption efficiency and the internal quantum efficiency of the sample increased greatly. The external quantum efficiency increased from 5.42% to 19.70%. Sub‐micrometer EuAl3(BO3)4 exhibits ultrahigh thermal stability, with a luminous intensity at 225 °C that is 128% of that at room temperature, meeting the conditions of extreme high‐temperature environments or high‐power LEDs. In summary, this work has great potential for application in W‐LED and presents a solution idea to solve the luminous intensity reduction of sub‐micrometer phosphors.