Enhanced Stability and Brightness through Co‐Substitution: Promoting Plant Growth with Green‐Excited Deep Red Phosphor Ca1‐zSrzLi1‐xMg2xAl3‐xN4:yEu2+

The research utilized a strategy of chemical unit co‐substitution, successfully developing a novel blue‐green to green excited, deep red‐emitting phosphor, Ca1‐zSrzLi1‐xMg2xAl3‐xN4:yEu2+ (CLA‐2xM‐zS:yEu, 0≤x≤0.8, 0.003≤y≤0.01, 0≤z≤1), through the replacement of [Li−Al]4+ by [Mg−Mg]4+. This phosphor uniquely converts unusable green light to growth‐enhancing deep red, optimizing it for outdoor agriculture. Doping with Sr creates traps, causing a redshift in emission peaks, as confirmed by 7Li nuclear magnetic resonance (NMR) spectra, indicating Li presence and lattice changes. Ca0.2Sr0.8Li0.5MgAl2.5N4:0.005Eu2+ (CLAM‐0.8S) phosphor maintained high luminescence intensity under extreme conditions of 85 °C/85% RH, demonstrating excellent photoluminescence performance and chemical stability, compared with conventional SrLi0.5MgAl2.5N4:0.005Eu2+ (SLMA) and SrLiAl3N4:0.005Eu2+(SLA). Experimental results surprised that the unique Ca0.2Sr0.8Li0.8Mg0.4Al2.8N4:0.005Eu2+ (CLA‐0.4M‐0.8S) prepared light‐converting film, which is mainly excited by green light, demonstrated a 20% increase in optical density of Chlorella compared to the PP film and a remarkable 97.5% increase compared to the control group without any film. These findings suggest that this film has significant potential for applications in outdoor agriculture and other fields.