The Anti‐Thermal Quenching Phosphor Landscape: Mechanisms, Materials, and Applications

ABSTRACT Anti‐thermal quenching (ATQ) is one of the most practically significant advances in inorganic luminescent materials. Unlike conventional phosphors, which suffer monotonic emission loss upon heating, ATQ phosphors exhibit stable or even increasing emission intensities as the temperature rises. This review provides a comprehensive and critical account of the ATQ phenomena, covering the mechanisms, material diversity, design strategies, measurement protocols, and the rapidly growing applications. We begin by establishing a conceptual framework for thermal quenching, followed by a systematic discussion of the principal ATQ mechanisms. We survey the full breadth of ATQ materials, including oxide‐based garnets, silicates, double perovskites, tungstates, phosphates, nitride and oxynitride phosphors, fluoride phosphors, halide perovskites, lead‐free halide double perovskites, zero‐dimensional metal halides, and organic–inorganic hybrid cluster‐based materials. We discuss the central role of activator ions, including Eu 2+ , Ce 3+ , Mn 2+ /Mn 4+ , Cr 3+ , Bi 3+ , and various trivalent lanthanides. The review critically addresses a methodological controversy surrounding the reproducibility and physical validity of reported ATQ behavior, emphasizing the importance of rigorous measurement protocols. Finally, we outline the key applications in solid‐state lighting, display backlighting, near‐infrared pc‐LED sources, non‐contact optical thermometry, X‐ray scintillators, anti‐counterfeiting, and information encryption, while articulating the scientific challenges and most promising directions for future research.