Direct Blue-LED Pumped Broadband Long-Wavelength Near-Infrared Emitter Based on Ni2+ Mono-Doped Double Perovskite Materials for Versatile Optical Applications

Long-wavelength near-infrared (NIR) phosphors (1000–2000 nm) have shown great promise in intelligent NIR spectroscopy technology fields. However, developing phosphors capable of directly absorbing blue light and emitting NIR light over 1000 nm still remains a significant challenge. Here, a series of ultra-broadband NIR phosphors with emission peaks longer than 1500 nm is achieved by incorporating single activator Ni²⁺ ion into ALaMgMO₆ (A = Ca, Sr, Ba; M = Sb, Nb, Ta) double perovskite hosts. Significantly, through a composition modulation strategy, the designed phosphors exhibit an intense blue light absorption band centered at 440 nm, making these Ni²⁺ mono-doped phosphors directly pumped by commercial blue LED chips without strictly introducing sensitized ions or the energy transfer process. The origination of effective blue-light excitable and ultra-broadband NIR-II to NIR-III phosphor emission is unraveled through Rietveld structural refinement and local symmetry analysis. Additionally, the developed phosphor demonstrated great potential in spectroscopic analysis, night-vision technology, non-destructive visualization, and information encryption and identification. This work provides a feasible strategy to solve the problem that Ni²⁺-doped phosphors cannot be directly pumped by blue light and can promote the development of more long-wavelength NIR materials for multiple photonic applications.