A Stable and Efficient Red‐Emitting Color Converter Based on K2SiF6:Mn4+ Phosphor‐in‐Glass Film for Next‐Generation Laser‐Excited Lighting and Display

Laser diodes (LDs) are expected to be the next‐generation high luminance sources because of the unobvious “efficiency droop” phenomenon under high power. To achieve high‐quality white lighting, red emission is essential for white lighting devices. K 2 SiF 6 :Mn 4+ (KSFM) is a highly suitable red phosphor for its strong broadband excitation in the UV and blue region and intense red emission at 631 nm. In addition, the ultranarrow emission makes it suitable for wide gamut displays. Herein, a stable and easily prepared red color converter, KSFM based phosphor‐in‐glass films on a coated sapphire substrate (CSA) is developed, which exhibits a high thermal conductivity of 32.02 W m −1 K −1 . Compared with the KSFM phosphor, this KSFM–CSA composite shows an overall increase in thermal quenching and irradiation resistance abilities. A wide color gamut covering 128% of the National Television Standards Committee (NTSC) standard white LD (WLD) is fabricated by coupling a green‐emitting CsPbBr 3 embedded glass plate and red‐emitting KSFM–CSA with blue LDs. Furthermore, a high‐quality WLD with a luminous flux (520 lm), luminous efficiency (93.0 lm W −1 ), and color rendering index (CRI, 81.4) is achieved. With its excellent properties, the KSFM–CSA has great potential in high‐power laser lighting and display.