Efficient Cr3+-activated NaInP2O7 phosphor for broadband near-infrared LED applications

Abstract

Recently, Cr³⁺-activated phosphors have garnered attention for broadband near-infrared phosphor converted light-emitting diode (NIR pc-LED) applications, but usually display low efficiency. Herein, we designed and synthesized a novel efficient broadband NIR phosphor NaIn_1−xP₂O₇:xCr³⁺ (in brief NIP:Cr³⁺) for NIR pc-LEDs. The NIP:0.04Cr³⁺ phosphor exhibits broadband NIR emission with a peak maximum at 856 nm and a full width at half maximum (FWHM) of 133 nm under 480 nm excitation. The crystal field parameters, luminescence decay curves, and temperature-dependence photoluminescence characteristics of the NIP:Cr³⁺ phosphor were investigated and discussed to understand its optical properties further. The NIP:0.04Cr³⁺ phosphor has a superior internal quantum efficiency (IQE) of ∼71.3%, and its external quantum efficiency (EQE) increased from ∼30.1% to ∼35.7% via the introduction of Li₂CO₃ as the flux. In addition, a NIR pc-LED was fabricated by combining the as-synthesized phosphor with a 460 nm blue LED chip, which can achieve a NIR output power of 39.11 mW and a photoelectric efficiency of 10.93% at 120 mA drive current, and the fabricated pc-LED performs well in night vision applications. These findings indicate that the NIP:Cr³⁺ phosphor has considerable application potential in broadband NIR pc-LEDs.