Evaluation of multi-resonant thermally activated delayed fluorescence emitters as photocatalysts

This thesis explores different classes of multi-resonant thermally activated delayed fluorescence (MR-TADF) compounds as photocatalysts (PCs) in photoinduced electron (PET) and photoinduced energy transfer (PEnT) reactions. The main objective is to expand on the existing library of MR-TADF PCs to cover a broader range of ground- and excited-state redox potentials and to access higher triplet energies than the current initial reported examples. Chapter 1 introduces photophysical and photochemical processes that take place in photocatalytic reactions. Different PC design strategies are presented and the concept of TADF is elucidated. Relevant examples of literature PCs and photocatalytic reactions are discussed. Chapter 2 studies four B/N doped MR-TADF emitters in their performance in PET and PEnT reactions. The influence of the structural changes between them on the ground- and excited-state redox potentials is investigated. The photocatalysts are employed in four model reactions and compared to literature reference PCs. Mechanistic studies and photostability tests explore their applicability in these reactions. Chapter 3 investigates four DiICz-based MR-TADF PCs as sensitizers in PEnT reactions. Two novel MR-TADF compounds were designed and a complete photophysical analysis is presented. In five different PEnT reactions, the influence of the singlet-triplet energy gap on the reaction progression and oxygen sensitivity is studied. The findings are compared to literature reference PCs. Chapter 4 presents three B/O doped MR-TADF compounds as PCs in PET and PEnT reactions. The optoelectronic properties are presented. These compounds are assessed in three photocatalysis reactions and their performance correlated to their structure.