Inducing B-site distortion in Gd3Sc1.5In0.5Ga3O12 garnet to accommodate Cr3+ ions: achieving high quantum efficiency and thermally stable broadband NIR phosphors for NIR spectroscopy applications

• • Internal quantum efficiency (IQE) reaches 98.29% under 460 nm excitation, approaching the theoretical limit for Cr3+-activated phosphors; this reduces non-radiative losses and enables higher NIR output per unit of blue pump power, directly lowering system energy consumption in portable spectroscopy. • • Thermal stability: 85.50% of initial emission intensity is retained at 423 K (150 °C), a critical threshold for high-power LED operation where junction temperatures routinely exceed 120 °C; this mitigates thermal quenching that otherwise degrades signal-to-noise ratios in continuous NIR monitoring. • • Broadband emission with FWHM >135 nm centered at 775 nm covers the first NIR biological window (700–900 nm), enabling deeper tissue penetration and multiplexed spectral analysis; the broad bandwidth arises from increased B-site distortion that lifts the parity selection rule, enhancing oscillator strength. • • Prototype NIR pc-LED achieves 19.75% power conversion efficiency (PCE) at 30 mA and 276.01 mW NIR output at 1200 mA, demonstrating scalability to high-drive currents; this output power exceeds typical requirements for handheld NIR spectrometers and non-destructive testing devices.