A novel bright cyan emitting phosphor of Eu2+ activated Ba6BO3Cl9 with robust thermal stability for full-spectrum WLED applications

Abstract

The currently available commercial white light-emitting diodes (WLEDs) suffer from a poor spectral continuity due to the absence of cyan light. Satisfactory bright cyan phosphors are urgently needed to promote the performance of WLEDs. Herein, we report a bright cyan-emitting phosphor Ba₆BO₃Cl₉:Eu²⁺. The internal quantum efficiency and external quantum efficiency of the Ba₆BO₃Cl₉:Eu²⁺ phosphor were measured to be 86.2% and 41.3%, respectively. Also, this phosphor exhibits strong endurance to luminescence thermal quenching, with the luminescence intensity at 150 °C retaining 93.9% of the value at room temperature. When applied in full-spectrum phosphor-converted WLEDs, the Ba₆BO₃Cl₉:Eu²⁺ phosphor may efficiently compensate for the lack of cyan light emission of WLED devices prepared using blue/yellow/red phosphor strategies and also contribute to the improvement of R_a (color rendering index) of WLED devices based on RGB (red/green/blue) phosphor strategies. In addition, the Ba₆BO₃Cl₉:Eu²⁺ phosphor can be applied as an independent efficient blue-cyan component to replace the blue light component in common WLEDs and reduces the proportion of high-energy blue light that is harmful to vision protection. These results demonstrate that Ba₆BO₃Cl₉:Eu²⁺ will have a wide range of potential applications in indoor healthy lighting as a cyan phosphor.