Temperature dependent optical properties of red emitting Na3GaF6:Mn4+ as a color converter for warm white LEDs

Abstract

Abstract This work presents and disentangles the temperature dependent optical properties of the red-emitting phosphor Na3GaF6:Mn4+. Moreover, crystal field and Racah parameters were investigated. It was proven that the material is suitable for the application in warm white LEDs due to its high quantum yield of about 83%, little thermal quenching of the photoluminescence up to 410 K, high lumen equivalent of about 220 lm/W, and strong absorption at 450 nm. In addition, different DFT approaches were used to investigate its band structure. The calculated data were compared to those obtained experimentally. Red phosphor spectra were calculated to evaluate the suitability of red line-emitting phosphors for the application in warm white emitting pcLEDs. Finally, warm white emitting LEDs comprising Na3GaF6:Mn4+ were constructed in order to show the potential of Na3GaF6:Mn4+ serving as a red component in phosphor blends for future warm white pcLEDs.