Thermally Activated Delayed Fluorescence (TADF) in Transition Metal Complexes

Thermally activated delayed fluorescence (TADF) is a temperature-dependent luminescence mechanism that allows the harvesting of both singlet and triplet excitons for fluorescence emission. Consequently, TADF-active compounds exhibit excellent photophysical properties, such as high luminescence efficiencies and long excited-state lifetimes. In recent times, TADF materials have found widespread applications in material and life science, most prominently in organic light-emitting diodes (OLEDs). Many design strategies for TADF emitters have emerged, amongst which the use of transition metal complexes constitutes an appealing approach. In this chapter, the theoretical background of the TADF phenomenon is discussed, different types of metal-based TADF emitters are introduced, selected case studies are highlighted, and an overview is given of the many applications of TADF materials in light-driven systems.