Recent progress in solution processable TADF materials for organic light-emitting diodes

Solution processable organic light-emitting diodes (OLEDs) are drawing increasing attention due to their potential application in low-cost, large-area, solid-state lighting. Meanwhile, thermally activated delayed fluorescence (TADF) materials have undergone significant progress since TADF-OLEDs exhibit extraordinary performance, which have been given priority in newly developed OLED technologies. Combining these two technologies to construct solution processable TADF-OLEDs is a newly developed area. In this review, we will generalize the design strategy for solution processable TADF materials. The spin-orbit coupling matrix element will be discussed as a new approach for highly efficient TADF. Then we will review materials used in solution-processed TADF-OLEDs, including small molecules, polymers and dendrimers. Furthermore, the prospects and remaining problems in this area will be discussed at the end of the review.