Two targets with one strategy: Insights into the role of aluminum atoms on the luminescence properties and thermal stability in Mn⁴⁺-doped calcium aluminozincate phosphor

Greenhouse plant cultivation (GPC) has attracted great attention in recent years, and the search for novel high efficiency far-red emitting phosphor is a crucial task. With this aim in view, in the present paper Ca₁₄Al₁₀Zn₆O₃₅:Mn⁴⁺ (CAZO:Mn⁴⁺) was investigated as a prototype phosphor. By simply incorporating excessive amount of Al, CA_10.25ZO:Mn⁴⁺ can meet two criteria simultaneously: it has relatively high quantum efficiency (QE) and good thermal stability, which tackle the goal of “killing two birds with one stone”. The internal QE (IQE) could further enhance from 83.9% to 90.0% due to the increased occupancy capability of Mn⁴⁺ in [AlO₆] octahedron, which is evidenced by solid-state ²⁷Al nuclear magnetic resonance (NMR) and energy dispersive spectra (EDS) measurements. In addition, the Mn⁴⁺ concentration-dependent excitation and emission spectra also demonstrate that the optimal doping concentration of Mn⁴⁺ in CA_10.25ZO host increases from 0.15 to 0.17 mol. Moreover, compared with CA_9.85ZO:0.15Mn⁴⁺, the thermal stability of CA_10.25ZO:0.15Mn⁴⁺ improves from 55% to 58% at 150 °C and 38%–45% at 200 °C, respectively. The as-fabricated plant growth LED devices shows better potential to be applied in GPC. This design strategy shown here provides an alternative pathway to further improve the luminescence properties of phosphors.