Breaking Concentration Quenching for Excellent Highly Efficient and Stable Narrowband Luminescence by Structural Ordering and Defect Regulation

Enhancing the performance of phosphor materials for wide‐color‐gamut and high‐brightness phosphor‐converted light‐emitting diodes (pc‐LEDs) represents a critical materials challenge. Improving quantum efficiency (QE) under concentration quenching constraints and maintaining thermal stability remain primary objectives. Here, we propose a nitrogen‐aluminosilicate host, La 1‐ x Si 9 Al 19 N 32 (L 1‐ x ASN): x Eu 2+ (0.1 ≤ x ≤ 1.0), with a highly condensed network. Through cationic ordering and optimized local crystal field configurations under ultrahigh activator doping ( x = 1.0), we achieved enhanced structural rigidity that effectively suppresses nonradiative energy transfer. This strategy resulted in external quantum efficiency (EQE) increases of 332% for the x = 1.0 sample relative to the x = 0.5 sample, the optimal doping concentration. The high structural rigidity and artificially created nitrogen vacancy defect compensate for emission loss during the thermal generation process, improving thermal stability at x = 1.0 by 278% compared to x = 0.5. The designed phosphor enables pc‐LEDs with a wide color gamut (106.6% NTSC) and ultrahigh brightness (8.56 × 10 6 cd m −2 ). This study advances the understanding of the relationship between luminescent properties and microstructure, demonstrating the effectiveness of structural ordering and defect engineering in enhancing the performance of LED phosphors.