Developing and optimizing novel Cr³⁺-activated inorganic NIR phosphors by combining triple-objective optimization and crystal field engineering

The development of novel near-infrared (NIR) phosphors that simultaneously satisfy diverse performance needs is extremely difficult in the vast materials space. In this paper, we propose a novel approach combining three-objective optimization (TOO) and crystal field engineering (CFE) for the development of new NIR phosphors. Utilizing the efficient optimization capabilities of machine learning in a high-dimensional space and the extended advantages of CFE in specific material systems, we successfully discovered a new NIR phosphor, LaGa0.5Sb1.5O6:Cr3+, with an excellent performance, which emerged from the LnA(m)B(2-m)O(6):Cr3+ (Ln = La, Gd; A = Al, Ga, In, Mg; B = Sb, Te; m = 0.5, 1/3) family. LaGa0.5Sb1.5O6:Cr3+ exhibited a broadband emission in the range 700-1200 nm (lambda(max) = 850 nm) with a full width at the half maximum (FWHM) of 200 nm and an internal quantum efficiency (IQE) of 55.4%. Moreover, 65% of its initial emission intensity could be maintained when heated to 393 K. This study paves a promising way for the rapid development of novel NIR phosphors with multiple essential properties.