High-Performance NaK<sub>2</sub>Li[Li<sub>3</sub>SiO<sub>4</sub>]<sub>4</sub>:Eu Green Phosphor for Backlighting Light-Emitting Diodes
Mu‐Huai Fang, Carl Osby M. Mariano, Kuan‐Chun Chen, Jiacheng Lin, Zhen Bao, Sebastian Mahlik, Tadeusz Leśniewski, Kuang‐Mao Lu, Ying‐Rui Lu, Yu‐Jong Wu, Hwo‐Shuenn Sheu, Jyh-Fu Lee, Shu‐Fen Hu, Ru‐Shi Liu, J. Paul Attfield
Abstract
Narrowband green phosphors with high quantum efficiency are required for backlighting white light-emitting diode (WLED) devices. Materials from the A[Li3SiO4]4:Eu2+ family have recently been proposed as having superior properties to industry-standard β-SiAlON green phosphors. Here, we show that a cheap, easily synthesized host NaK2Li[Li3SiO4]4 (NKLLSO) doped with a mixture of Eu2+ and Eu3+ is an outstanding narrowband green phosphor, with an external quantum efficiency of 51% and superb thermal stability (97.1% of room-temperature performance at 150 °C). Structural studies reveal that green emission occurs from two Eu2+ sites, while Eu3+ introduces a high concentration of vacancies that may suppress quenching from energy transfer between Eu2+ sites. A WLED package constructed using our NKLLSO phosphor shows extremely high color vividness, competitive with a β-SiAlON comparator. This work will stimulate further research on efficient green phosphors for practical WLED devices.