Moisture‐Resistant Mn4+‐Doped Core–Shell‐Structured Fluoride Red Phosphor Exhibiting High Luminous Efficacy for Warm White Light‐Emitting Diodes. Issue 12 (21st January 2019)

• Record Type: Journal Article
• Authors: Huang, Decai; Zhu, Haomiao; Deng, Zhonghua; Zou, Qilin; Lu, Hongyu; Yi, Xiaodong; Guo, Wang; Lu, Canzhong; Chen, Xueyuan
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 12(2019)
• Page Start: 3843
• Page End: 3847
• Publication Date: 2019-01-21
• Subjects: cation exchange -- luminous efficacy -- Mn4+ -- phosphors -- photoluminescence; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201813363
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: K2 TiF6 :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 K2 TiF6 :Mn 4+ @K2 TiF6 phosphor. The outer K2 TiF6 shell acts as a shield for preventing moisture in the air from hydrolyzing the internal MnF6 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 (Ra ). 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 K2 TiF6 :Mn 4+ @K2 TiF6 phosphor. Abstract : A reverse cation‐exchange strategy is presented for the construction of a core–shell‐structured K2 TiF6 :Mn 4+ @K2 TiF6 (KTF:Mn 4+ @KTF) phosphor. The KTF shell shields the KTF:Mn 4+ core from ambient moisture and prevents hydrolysis of the internal MnF6 2− group. The phosphor exhibits a high photoluminescence quantum yield and excellent moisture‐resistant properties.