Thermally Activated Delayed Fluorescence (TADF) Materials Based on Earth‐Abundant Transition Metal Complexes: Synthesis, Design and Applications

Materials exhibiting thermally activated delayed fluorescence (TADF) based
on transition metal complexes are currently gathering significant attention
due to their technological potential. Their application extends beyond
optoelectronics, in particular organic light-emitting diodes (OLEDs) and
light-emitting electrochemical cells (LECs), and include also photocatalysis,
sensing, and X-ray scintillators. From the perspective of sustainability,
earth-abundant metal centers are preferred to rarer second- and
third-transition series elements, thus determining a reduction in costs and
toxicity but without compromising the overall performances. This review
offers an overview of earth-abundant transition metal complexes exhibiting
TADF and their application as photoconversion materials. Particular attention
is devoted to the types of ligands employed, helping in the design of novel
systems with enhanced TADF properties.