Effects of the relative position and number of donors and acceptors on the properties of TADF materials

Thermally activated delayed fluorescence (TADF) emitters have attracted great attention for their use in organic light-emitting diodes since they can potentially realize 100% internal quantum efficiency by utilizing both singlet and triplet excitons due to an efficient reverse intersystem crossing process. However, forming a rational molecular design strategy is still challenging for high-performance TADF emitters. It is critical to understand the key factors that affect the performance of TADF materials. In this regard, this review focuses on the recent progress made in the design and synthesis of TADF materials controlled by the position and number of donor and acceptor units in different molecular structures. Reasonable molecular design principles have been summarized with the photophysical and electroluminescence characteristics of TADF materials. Furthermore, design guidelines and future prospects for high-performance TADF emitters are proposed for their future development.