Achieving Ultra-Broadband Sunlight-Like Emission in Single-Phase Phosphors: The Interplay of Structure and Luminescence.

The quest for artificial light sources that mimic sunlight's spectral characteristics has been a long-standing endeavor, particularly for applications in anticounterfeiting, agriculture, and color hue detection. Conventional sunlight simulators, such as xenon lamps, are often cost-prohibitive and bulky, limiting their adoption. In this regard, the development of a series of single-phase phosphors Ca 9 LiMg 1-x Al 2x/3 (PO 4 ) 7 :0.1Eu 2+ (x = 0-0.75) with sunlight-like emission described in this work holds immense promise as a compact and economical light source alternative. The phosphors have been obtained by an original heterovalent substitution method and emit a broad spectrum that encompasses the entire visible region, spanning from violet to deep red. Notably, the phosphor with x = 0.5 exhibits an impressive full width at half maximum of 330 nm. A synergistic interplay of experimental investigations and density-functional theory calculations unveils the underlying mechanism behind sunlight-like emission. It is attributed to the local structural perturbations introduced by the heterovalent substitution of Al 3+ for Mg 2+ , leading to a varied distribution of Eu 2+ within the lattice. Subsequent characterization of a series of organic dyes combining absorption spectroscopy with convolutional neural network analysis convincingly demonstrates the potential of this phosphor in portable photodetection devices. Broad-spectrum light source testing empowers our model to precisely differentiate dye patterns. This points to the phosphor being ideal for mimicking sunlight. And beyond this demonstrated application, we envision the phosphor's utility in other relevant domains, including visible light communication and smart agriculture. These findings not only enrich our understanding of luminescent materials design but also pave the way for advancements in various application areas. This article is protected by copyright. All rights reserved.