The electronic and optical properties of a narrow-band red-emitting nanophosphor K2NaGaF6:Mn4+ for warm white light-emitting diodes

Chunyan Jiang; Mikhail G. Brik; Lihua Li; Liyi Li; Jie Peng; Jianan Wu; Maxim S. Molokeev; Ka-Leung Wong; Mingying Peng

doi:10.1039/C7TC05098D

The electronic and optical properties of a narrow-band red-emitting nanophosphor K₂NaGaF₆:Mn⁴⁺ for warm white light-emitting diodes†

Chunyan Jiang,^a Mikhail G. Brik,^cde Lihua Li,^a Liyi Li,^a Jie Peng,^a Jianan Wu,^a Maxim S. Molokeev,

^fg Ka-Leung Wong

^h and Mingying Peng

*^ab

Author affiliations

* Corresponding authors

^a The China-Germany Research Center for Photonic Materials and Device, State Key Laboratory of Luminescent Materials and Devices, and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, P. R. China
E-mail: pengmingying@scut.edu.cn

^b School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong 529020, P. R. China

^c College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China

^d Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu 50411, Estonia

^e Institute of Physics, Jan Długosz University, Armii Krajowej 13/15, PL-42200 Częstochowa, Poland

^f Laboratory of Crystal Physics, Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk 660036, Russia

^g Siberian Federal University, Krasnoyarsk 660041, Russia

^h Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, P. R. China

Abstract

Recently, as a key red component in the development of warm white light-emitting diodes (WLEDs), Mn⁴⁺-doped fluorides with narrow red emission have sparked rapidly growing interest because they improve color rendition and enhance the visual energy efficiency. Herein, a red nanophosphor, K₂NaGaF₆:Mn⁴⁺, with a diameter of 150–250 nm has been synthesized using a simple co-precipitation method. Rietveld refinement reveals that it crystallizes in the space group Fm [3 with combining macron] m with the cell parameter a = 8.25320(4) Å. The exchange charge model (ECM) has been used to calculate the energy levels of Mn⁴⁺ ions in K₂NaGaF₆, which match well with the experimental spectra. The as-synthesized phosphor exhibits a narrow red emission at around 630 nm (spin-forbidden ²E_g → ⁴A₂ transition of Mn⁴⁺ ions) when excited at 365 nm (⁴A_2g → ⁴T_1g) and 467 nm (⁴A_2g → ⁴T_2g), with a quantum efficiency (QE) of 61% and good resistance to thermal quenching. Based on the structure, the formation mechanism of ZPL has been discussed. In addition, the concentration-dependent decay curves of Mn⁴⁺ in K₂NaGaF₆ were fitted using the Inokuti–Hirayama model, suggesting that the dipole–dipole interactions determine the concentration quenching. Finally, encouraged by the good performance, a warm LED with a CRI of 89.4 and CCT of 3779 K was fabricated by employing the title nanophosphor as the red component. Our findings suggest that K₂NaGaF₆:Mn⁴⁺ can be a viable candidate for the red phosphor used in warm WLEDs.

Journal of Materials Chemistry C

The electronic and optical properties of a narrow-band red-emitting nanophosphor K₂NaGaF₆:Mn⁴⁺ for warm white light-emitting diodes†

Abstract

Supplementary files

Article information

Download Citation

Permissions

The electronic and optical properties of a narrow-band red-emitting nanophosphor K₂NaGaF₆:Mn⁴⁺ for warm white light-emitting diodes

Social activity

Search articles by author

Spotlight

Advertisements

Journal of Materials Chemistry C