Narrow Red Emission Band Fluoride Phosphor KNaSiF6:Mn(4+) for Warm White Light-Emitting Diodes.
Red phosphors AMF6:Mn(4+) (A = Na, K, Cs, Ba, Rb; M = Si, Ti, Ge) have been widely studied due to the narrow red emission bands around 630 nm. The different emission of the zero-phonon line (ZPL) may affect the color rendering index of white light-emitting diodes (WLED). The primary reason behind the emergence and intensity of ZPL, taking KNaSiF6:Mn(4+) as an example, was investigated here. The effects of pressure on crystal structure and luminescence were determined experimentally and theoretically. The increase of band gap, red shift of emission spectrum and blue shift of excitation spectrum were observed with higher applied pressure. The angles of ∠FMnF and ∠FMF(M = Si, Ti, Ge) were found clearly distorted from 180° in MF6(2-) octahedron with strong ZPL intensity. The larger distorted SiF6(2-) octahedron, the stronger ZPL intensity. This research provides a new perspective to address the ZPL intensity problem of the hexafluorosilicate phosphors caused by crystal distortion and pressure-dependence of the luminescence. The efficacy of the device featuring from Y3Al5O12:Ce(3+) (YAG) and KNaSiF6:Mn(4+) phosphor was 118 lm/W with the color temperature of 3455 K. These results reveal that KNaSiF6:Mn(4+) presents good luminescent properties and could be a potential candidate material for application in back-lighting systems.
School of Optoelectronic Information, Chongqing University of Technology , Chongqing 400054, China.
Ye
Y
Jin
Mu-Huai
MH
Fang
Institute of Experimental Physics, University of Gdańsk , 80-952 Gdańsk, Poland.
Marek
M
Grinberg
Institute of Experimental Physics, University of Gdańsk , 80-952 Gdańsk, Poland.
Sebastian
S
Mahlik
Institute of Experimental Physics, University of Gdańsk , 80-952 Gdańsk, Poland.
Tadeusz
T
Lesniewski
College of Sciences, Chongqing University of Posts and Telecommunications , Chongqing 400065, China.|Institute of Physics, University of Tartu , Tartu 50411, Estonia.|Institute of Physics, Jan Dlugosz University , Czestochowa PL-42200, Poland.
M G
MG
Brik
Guan-Yu
GY
Luo
Jauyn Grace
JG
Lin
Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology , Taipei 106, Taiwan.
Ru-Shi
RS
Liu
KNaSiF6:Mn4+; ZPL; high pressure; red phosphor; warm white LED