Broadband near-infrared (NIR) phosphors have gained growing interest in applications such as food detection, plant growth and night vision lighting. However, designing NIR phosphors with large full width at half maximum (FWHM) is challenging. In this study, we introduce a novel blue light excitable Cr3+-Yb3+-Er3+ tri-doped KAlP2O7 (KAPO) phosphor, which exhibits luminescence in ultra-wide NIR region, including broadband NIR-II luminescence with the FWHM of 302nm and sharp NIR-III luminescence at 1538nm. Fluorescence decay curves confirmed the presence of energy transfer. In addition, the NIR optical thermometry was developed using the non-thermally coupled energy states of 4T2→4A2 (Cr3+) and 4I13/2→4I15/2 (Er3+), with the highest absolute (SA) and relative sensitivity (SR) values determined to be 122.2 × 10−4 K−1 (T = 473K) and 0.76% K−1 (T = 448K), respectively. In addition,the prepared phosphor can be efficiently excited by various wavelengths including 377nm ultraviolet light, 468nm blue light, and 808/980nm near infrared light, suggesting its promising applications in anti-counterfeiting. The NIR phosphor-converted LED (pc-LED) was fabricated using KAPO: 0.01Cr3+, 0.002Yb3+, 0.01Er3+ phosphor and a 470nm LED chip, demonstrating notable potential in night vision technology.
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