Recent Advances in Red and Near-Infrared Organic Room-Temperature Phosphorescent Materials

Organic room-temperature phosphorescent (RTP) materials, particularly those with emission bands in the red and near-infrared (red/NIR) regions, show great potential in biomedical imaging due to deep penetration depth and minimal background interference. This review systematically summarizes the latest advances in this field, focusing on molecular design strategies and innovations in biomedical applications. It specifically discusses the mechanisms for enhancing phosphorescence and achieving emission redshift across various systems, including purely organic small molecules, polymers, polymeric matrices, and host–guest doping systems. From an application perspective, the article also elucidates the unique value of these materials in areas such as biomedical imaging, high-sensitivity sensing, and information anticounterfeiting. This review aims not only to catalog the recent progress but also to provide insights into the structure–property relationships that will guide the rational design of next-generation organic RTP materials, ultimately accelerating their translation into real-world applications.