Boosting Red Luminescence of Mn4+ in Tantalum Heptafluoride Based on an Ab Initio-Facilitated Sensitizer and Hydrophobic Surface Modification

Jiansheng Huo; Quwei Ni; Haiyong Ni; Tan Li; Yuanyuan Meng; Junhao Li; Jianbang Zhou

doi:10.1021/acsami.3c04734

Boosting Red Luminescence of Mn⁴⁺ in Tantalum Heptafluoride Based on an Ab Initio-Facilitated Sensitizer and Hydrophobic Surface Modification

ACS Appl Mater Interfaces. 2023 Apr 26;15(16):20252-20265. doi: 10.1021/acsami.3c04734. Epub 2023 Apr 14.

Authors

Jiansheng Huo¹, Quwei Ni^{1

2}, Haiyong Ni¹, Tan Li³, Yuanyuan Meng⁴, Junhao Li¹, Jianbang Zhou¹

Affiliations

¹ State Key Laboratory of Rare Metals Separation and Comprehensive Utilization, Guangdong Province Key Laboratory of Rare Earth Development and Application, Institute of Resources Utilization and Rare Earth Development, Guangdong Academy of Sciences, Guangzhou 510651, P. R. China.
² School of Chemistry, South China Normal University, Guangzhou 510006, P. R. China.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, P. R. China.
⁴ College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China.

PMID: 37058140
DOI: 10.1021/acsami.3c04734

Abstract

A narrow-band red-light component is critical to establish high color rendition and a wide color gamut of phosphor-converted white-light-emitting diodes (pc-WLEDs). In this sense, Mn⁴⁺-doped K₂SiF₆ fluoride is the most successful material that has been commercialized. As with K₂SiF₆:Mn⁴⁺ phosphors, Mn⁴⁺-doped tantalum heptafluoride (K₂TaF₇:Mn⁴⁺) fulfills a similar luminescence behavior and has been brought in a promising narrow-band red phosphor. But the limited brightness and low moisture-resistant performances have inevitably blocked its practical application. Herein, we employed the density functional theory (DFT)-based ab initio estimation approach to quickly identify the proper sensitizer by systematically investigating the electronic-band coupling between the several possible sensitizers (Rb, Hf, Zr, Sn, Nb, and Mo) and the luminescent center (Mn). Combined with experimental results, Mo was demonstrated to be the optimal sensitizer, which resulted in a 60% enhancement of the emission. On the side, the moisture sensitivity has been effectively improved via grafting the hydrophobic octadecyltrimethoxysilane (ODTMS) layer on the phosphor surface. Through employing the K₂TaF₇:Mn⁴⁺,Mo⁶⁺@ODTMS composite as a red component, warm WLEDs with good performance were achieved with a correlated color temperature (CCT) of 4352 K, a luminous efficacy (LE) of 90.1 lm/W, and a color rendering index (Ra) of 83.4. In addition, a wide color gamut reaching up to 102.8% of the NTSC 1953 value could be realized. Aging tests at 85 °C and 85% humidity for 120 h on this device manifested that the ODTMS-modified phosphor had much better moisture stability than that of the unmodified one. These studies provided viable tools for optimizing Mn⁴⁺ luminescence in fluoride hosts.

Keywords: Mn4+ ions; density functional theory; moisture resistance; narrow-band red emission; warm WLEDs; wide color gamut.