Moisture‐Resistant Mn 4+ ‐Doped Core–Shell‐Structured Fluoride Red Phosphor Exhibiting High Luminous Efficacy for Warm White Light‐Emitting Diodes

作者：Decai Huang, Haomiao Zhu, Zhonghua Deng, Qilin Zou, Hongyu Lu, Xiaodong Yi, Wang Guo, Can‐Zhong Lu, Xueyuan Chen · 发表于：Angewandte Chemie International Edition · 年份：2018 · DOI：10.1002/anie.201813363 · 被引用次数：175 · 研究领域：Luminescence Properties of Advanced Materials、Inorganic Fluorides and Related Compounds、Advanced Photocatalysis Techniques

Abstract K 2 TiF 6 :Mn 4+ is a highly efficient narrow‐band emission red phosphor with promising applications in white light‐emitting diodes (LEDs) and wide‐gamut displays. Nevertheless, the poor moisture‐resistant properties of this material hinder commercialization. A convenient reverse cation‐exchange strategy is introduced for constructing a core–shell‐structured K 2 TiF 6 :Mn 4+ @K 2 TiF 6 phosphor. The outer K 2 TiF 6 shell acts as a shield for preventing moisture in the air from hydrolyzing the internal MnF 6 2− group, while effectively cutting off the path of energy migration to surface defects, thereby increasing the emission efficiency (especially for the phosphors doped with high concentrations of Mn 4+ ). Employed as a red phosphor, the packaged white LED exhibits an extraordinarily high luminous efficacy of 162 lm W −1 , a correlated color temperature (CCT) of 3510 K, and a color rendering index of 93 (R a ). Aging tests performed on this device at 85 °C and 85 % humidity for 480 h retain up to 89 % luminous efficacy. The findings could facilitate commercial application of K 2 TiF 6 :Mn 4+ @K 2 TiF 6 phosphor.