Broadband NIR phosphor with high external quantum yield and application of smoke penetration imaging

Currently, near-infrared (NIR) phosphors have been applied in many emerging fields, therefore, there is an urgent need to investigate the high-efficiency broadband NIR phosphors with different emission wavelengths to meet the demands of widespread applications. However, the bottleneck of relatively low photoluminescence quantum yield (PL QY) has significantly constrained the performance of NIR phosphors. Herein, an efficient Na_0.6Al_0.8Nb_1.2(PO₄)₃:Cr³⁺ (NANP:Cr³⁺) phosphor with 815 nm NIR emission was successfully synthesized. Moreover, the achieved external PL QY is up to 53.9 % under 460 nm blue-light excitation by the proper introduction of Yb³⁺. A NIR phosphor-converted light-emitting diode (NIR pc-LED) is fabricated by using the NANP:Cr³⁺,Yb³⁺ phosphor and a 460 nm blue diode chip. The photoelectric conversion efficiency is 28.8 % at 10 mA drive current. Furthermore, we demonstrate a new application using the encapsulated NIR pc-LED. Thanks to the excellent penetration ability of NIR light, so that demonstrating better performance in an environment where human vision is poor. The NIR pc-LED was successfully used as the lighting source for penetration in smoke and water mist, and the imaging ability suggests that the NIR phosphors can be used in the field of transportation and fire protection.