An efficient and stable narrow band Mn4+-activated fluorotitanate red phosphor Rb2TiF6:Mn4+ for warm white LED applications

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 6; no. 32; pp. 8670 - 8678
• Main Authors: Wang, L Y, Song, E H, Zhou, Y Y, Deng, T T, S Ye, Zhang, Q Y
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2018
• Subjects: Crystal structure; Light emitting diodes; Luminescence; Moisture resistance; Morphology; Optical properties; Phosphors; Quantum efficiency; Synthesis; Thermal resistance; Thermal stability; Titanium dioxide
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c8tc02615g

A Rb-based fluorotitanate stable narrow band red-emitting phosphor Rb2TiF6:Mn4+ with an internal quantum efficiency of 91% was synthesized through an efficient and mild coprecipitation method. Herein, by simultaneously using H2TiF6 as a Ti source to replace TiO2 and using H2O as a substitute for solvent HF, the total consumption of toxic HF can be effectively reduced in the synthesis processes. Further optimization of phosphors can be achieved by investigating the impact of doping concentration, amount of solvent added and reaction stirring time on the luminescence properties of the phosphors. The crystal structures, morphologies, luminescence performance, thermal stability, moisture resistance, and device performance of the as-synthesized phosphors were systematically investigated. The obtained Rb2TiF6:Mn4+ presents more exceptional luminescence properties, thermal stability and longevity under LED working conditions compared to Rb2ZrF6:Mn4+, and worthy of note, its unmodified moisture resistance is obviously superior to that of other Rb-based fluoride red phosphors. By using Rb2TiF6:Mn4+ as a red-light component, a high-quality LED device with desirable performance (Ra = 89, CCT = 3730 K and LE = 158.8 lm W−1) can be obtained, and the variable drive current and temperature tests revealed that the resultant device exhibits excellent performance, which further demonstrates that Rb2TiF6:Mn4+ has efficient and stable light-emitting properties and can be used to fabricate high power WLEDs with preferable heat resistance.