Organic Thermally Activated Delayed Fluorescence (TADF) Compound as The Photosensitizer in CO2 Photoreduction: Taking 4CzIPN as An Example

Abstract Over the past decades, excessive CO₂ emissions have caused severe environmental problems, primarily global warming and climate change. To address these challenges, researchers have developed photocatalytic approaches to convert CO₂ into high‐value‐added chemicals. The development of efficient, green, and cost‐effective photocatalytic CO₂ reduction systems represents a crucial step toward sustainable energy solutions. However, replacing noble metal‐based photosensitizers, which are widely used in CO₂ reduction, with more sustainable alternatives remains challenging. Thermally activated delayed fluorescence (TADF) compounds have emerged as promising organic photosensitizers, offering high quantum efficiency, long lifetimes, and wide redox window. Notably, 1,2,3,5‐Tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene (4CzIPN), a prototypical TADF compound, has demonstrated exceptional performance in various photocatalytic CO₂ reduction systems. This review systematically summarizes recent advances in TADF‐based photosensitizers, particularly 4CzIPN, for photocatalytic CO₂ reduction, while elucidating their underlying reaction mechanisms.