Near-Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications.

Near-infrared materials exhibiting high photoluminescence quantum yields present a promising avenue to broaden our capacity and threshold for detection and manipulation, extending beyond the visible emission range. The spotlight has shifted to near-infrared (NIR) luminescent materials emitting beyond 1000 nm, with growing interest due to their unique characteristics. The ability of NIR-II emission (1000-1700 nm) to penetrate deeply and transmit independently positions these NIR luminescent materials for applications in optical-communication devices, bioimaging, and photodetectors. The combination of rare earth metals/transition metals with a variety of matrix materials provides a new platform for creating new chemical and physical properties for materials science and device applications. In this review, we summarize the recent advancements in NIR emission activated by rare earth and transition metal ions and illustrate their role in applications spanning bioimaging, sensing, and optoelectronics. We start from the various synthesis techniques, including high-temperature solid-state, hydrothermal, and thermal decomposition methods, on how to delicately incorporate the rare-earth/transition metals to the NIR various matrixes, each imparting distinct characteristics to these luminescent materials. We then extend the discussion to strategies of enhancing excitation absorption and emission efficiency, spotlighting innovations like dye sensitization and surface plasmon resonance effects. Subsequently, a significant focus is placed on functionalization strategies and their applications. Finally, we provide a comprehensive analysis of the challenges and proposed strategies for rare earth/transition metal ion-doped near-infrared luminescent materials, summarizing the insights of each section. This article is protected by copyright. All rights reserved.