Strategic Incorporation of h‐BN@SiO ₂ into Phosphor‐in‐Glass Film Enabling Thermally Robust Color Converters for Laser‐Driven Lighting

ABSTRACT Phosphor‐in‐glass film (PiGF) has emerged as an advanced color converter for laser lighting owing to its simple fabrication and versatility with various phosphors. Nevertheless, the inherently poor thermal conductivity of the glass endows PiGF with a low saturation threshold and limited radiation resistance, hindering its practical applications. Here, a series of Y 3 Al 5 O 12 :Ce 3+ ‐h‐BN@SiO 2 ‐PiGF (Y‐B@S‐PiGF) are fabricated by incorporating amorphous silica‐coated h‐BN (h‐BN@SiO 2 ) into the glass matrix as a heat transfer medium. Compared with the original h‐BN, h‐BN@SiO 2 not only establishes an extensive thermal conduction network within the glass matrix due to its homogeneous dispersion, but also strengthens the interfacial interaction with the glass matrix. Consequently, Y‐B@S‐PiGF with 40 wt% h‐BN@SiO 2 demonstrates superior performance with a luminous flux (LF) of 6545 lm and luminous efficacy (LE) of 153.1 lm W − 1 @ 23.7 W·mm − 2 , outperforming most reported PiGF@sapphire. By supplementing red CaAlSiN 3 :Eu 2+ (CASN:Eu) phosphor and optimizing the mass ratio of Y 3 Al 5 O 12 : Ce 3+ (YAG:Ce) to CASN:Eu (YtC ratio), the Y‐C‐B@S‐PiGFs achieve high‐quality white light with a tunable color rendering index (CRI) of 70–86 and correlated color temperature (CCT) of 3269–7906 K in rotational mode. The assembled white laser diode (WLD) module exhibits efficient and stable illumination performance, demonstrating great potential for next‐generation laser‐driven lighting.