Enhancement of zero phonon line for Na2TiF6:Mn4+, Li+ phosphors induced by Li+

Abstract

Red light purity of red emitting phosphor is an important factor for using in warm white light-emitting diodes (WLEDs). In order to obtain red emitting phosphor with good red light purity, a series of Na2TiF6:0.08Mn4+, xLi+ samples were prepared with the cation exchange method. Phenomena of zero phonon line as the strongest peak and strong enhancement induced by Li+ were observed. The mechanisms of the phenomena are discussed and proposed. From the result of temperature-dependent behavior measurement and stability test, it can be known that the optimal sample exhibited good thermal stability and color stability under WLEDs working conditions. Finally, prototype WLEDs was fabricated with the optimal sample and Y3Al5O12:Ce3+ (YAG:Ce3+) based on InGaN chip. Warm white light with low correlated color temperature (CCT = 4393 K) and high color rendering index (Ra = 90.5 and R9 = 89) was obtained, making it had potential application for blue light-based warm WLEDs.