Ultra-broadband and high-efficiency phosphors to brighten NIR-II light source applications

Achieving phosphor-converted light-emitting diodes (pc-LEDs) for portable NIR spectroscopy applications has evoked enormous demand for high-efficiency broadband NIR-II (1,000–1,700 nm) phosphors. Herein, a series of Li-alloyed (Li/Mg)O:Ni 2+ phosphors with tunable NIR-II emission is prepared. By alloying Li-ions into MgO:Ni 2+ , we break the uniform coordination environment of Ni 2+ emitters by substitutional disorder and induce many crystallographically equivalent Ni 2+ emitters. This leads to large spectral tuning in the NIR-II region with the peak position and full-width at half-maximum (FWHM) varying in the 1,330–1,460 and 204–350 nm regions, respectively. Consequently, ultra-broadband (FWHM = 350 nm, 10.1 mW at 350 mA) and high-efficiency (FWHM = 204 nm, 19.7 mW at 350 mA) NIR-II pc-LEDs have been fabricated simultaneously based on the explored phosphors, and its applications are also demonstrated. We anticipate that this strategy can be used to explore other NIR phosphor systems, thus opening up new avenues for next-generation NIR spectroscopy technology.