Introducing Uranium as the Activator toward Highly Stable Narrow-Band Green Emitters with Near-Unity Quantum Efficiency

Searching for new green phosphors featured with a narrow band, small Stokes-shift, high thermal stability, and decent chemical resistance is critical for white light emitting diodes (LEDs) in liquid-crystal displays (LCDs). For the first time, we introduce a uranyl (UO22+) compound with inherently bright green emission as the activator for fabricating high-performance phosphor-converted LEDs. UO22+ was successfully incorporated into a dense, rigid, UV-transparent, and photoluminescent borate framework (Na[(UO2)B6O10(OH)]·2H2O (NaUBO-4)) exhibiting surprisingly high internal and external quantum efficiencies (close to 100% and 92% for excitation at 260 nm, respectively), low thermal quenching (96% of the initial emission intensity can be maintained at 120 °C), and high luminous stability after long-term exposure to moisture and UV radiation. Furthermore, the vibronically coupled emission from UO22+ with relatively narrow emission bands leading to a wide color range of 95% of the National Television System ...