Enhanced far-red luminescence in Ca14Al10Zn6O35:Mn4+, Mg2+ phosphors via local structure modulation

Far-red light (700–800 nm) plays a vital role in promoting photosynthetic activity and regulating photomorphogenesis in controlled-environment agriculture. However, the development of efficient far-red phosphors remains a significant challenge. In this study, a high-performance far-red emitting (Ca,Mg)₁₄Al₁₀Zn₆O₃₅:Mn⁴⁺ (CMAZO:Mn⁴⁺) phosphor, was developed via a cationic substitution strategy. Upon blue light excitation, CMAZO:Mn⁴⁺ exhibits bright far-red emission centered at 720 nm, aligning well with the absorption spectrum of phytochromes. The partial substitution of Ca²⁺ by smaller Mg²⁺ ions in the Ca₁₄Al₁₀Zn₆O₃₅:Mn⁴⁺ (CAZO:Mn⁴⁺) lattice induces lattice shrinkage and enhances structural rigidity, thereby effectively suppressing nonradiative relaxation pathways. As a result, CMAZO:Mn⁴⁺ achieves an emission intensity 1.22 times greater than that of CAZO:Mn⁴⁺ and demonstrates enhanced thermal stability. At the optimal Mg²⁺ doping content, the phosphor reaches a quantum efficiency of 84.0 %. Notably, at 423 K, it maintains 86 % of its room temperature emission intensity. The pc-LED device, fabricated by integrating CMAZO:Mn⁴⁺C with an InGaN blue chip, demonstrates excellent photoelectric performance. These results suggest that CMAZO:Mn⁴⁺ is a promising far-red luminescent material for advanced indoor plant lighting applications.