KuehneLab is concerned with functional molecules (small and large) for applications in the area of photonics and biomedicine. We focus on snthetic materials for modern luminescence, detection, and medical treatment. Furthermore, we explore new ways for structure formation and make non-processable polymers moldable and small particles self-assemble into any desired shape.
Hot Exciplexes in U-Shaped TADF Molecules with Emission from Locally Excited States
Rapid reverse intersystem crossing and high color purity are vital characteristics of emitters with thermally activated delayed fluorescence in opto-electronic devices. We present a new approach, called “hot exciplexes” that enables access to both attributes at the same time. Hot exciplexes are produced by coupling facing donor and acceptor moieties to an anthracene bridge, yielding an exciplex with large T1 to T2 spacing. The hot exciplex model is investigated using optical spec-troscopy and quantum chemical simulations. Reverse intersystem crossing is found to occur preferentially from the T3 to the S1 state within only a few nanoseconds. Application and practi-cality of the model are shown by fabrication of organic light-emitting diodes with up to 32 % hot exciplex contribution and low efficiency roll-off.