A Unified Photophysical Framework for Anomalous Cr‐Activated Near‐Infrared Emission in Oxide Hosts

ABSTRACT Broadband near‐infrared (NIR) emission from Cr‐activated oxides has attracted increasing interest for applications in nondestructive inspection, night vision, and biomedical photonics. However, several recently reported NIR bands have been attributed to unconventional coordination geometries of , in conflict with established mechanistic understanding and hindering the development of reliable materials‐design and optimization principles. Here we present a unified photophysical framework for these anomalous emissions by combining first‐principles defect thermodynamics with configuration‐coordinate excited‐state modeling. Our analysis demonstrates that tetrahedrally coordinated is intrinsically non‐emissive. The reported anomalous NIR emissions—including the 730–780 nm bands in tetrahedral gallates, the 900 nm emission in spinels, and the apparent multicenter emission in —originate instead from locally distorted octahedral environments. Such distortions arise from lattice heterogeneity, intrinsic point defects (e.g., cation vacancies), solid‐solution–induced site inequivalence, or trace impurity phases formed during synthesis. This unified interpretation resolves long‐standing inconsistencies in the literature and identifies distorted octahedral coordination as the key structural motif governing broadband Cr‐based NIR emission in the 700–1000 nm range. The results establish physically grounded design guidelines for engineering high‐performance Cr‐activated NIR phosphors through controlled crystal‐field weakening and local symmetry breaking.