Abstract
Triplet exciton harvesting is a key issue for high-efficiency organic light-emitting diodes (OLEDs). Recently, we demonstrated an alternative pathway for efficient fluorescence-based OLEDs by applying thermally activated delayed fluorescence (TADF) as a singlet energy generation mechanism using materials with a small energy gap between singlet and triplet excited states. The resulting fluorescence-based OLEDs with TADF materials as dopants showed very high internal electroluminescence quantum efficiencies approaching nearly 100% for blue, green, yellow, and red emission. We also found that the OLEDs employing this triplet energy harvesting process have significantly enhanced device operational stability. In this article, we will review the unique features of this triplet harvesting process, i.e., TADF-assisted fluorescence.
