《Stable Blue Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes with Three Times Longer Lifetime than Phosphorescent Organic Light-Emitting Diodes》
来源专题：绿色印刷—LED
编译者：张宗鹏
发布时间：2016-04-13
Abstract
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High quantum efficiency above 18% and extended lifetime three times longer than that of phosphorescent organic light-emitting diodes (OLEDs) are demonstrated in blue thermally activated delayed fluorescent OLEDs.
Highly efficient, simplified, solution-processed thermally activated delayed-fluorescence organic light-emitting diodes can be realized by using pure-organic thermally activated delayed fluorescence emitters and a multifunctional buffer hole-injection layer, in which high EQE (≈24%) and current efficiency (≈73 cd A−1) are demonstrated. High-efficiency fluorescence red-emitting and blue-emitting devices can also be fabricated in this manner.
Abstract
The electron positive boron atom usually does not contribute to the frontier orbitals for several lower-lying electronic transitions, and thus is ideal to serve as a hub for the spiro linker of light-emitting molecules, such that the electron donor (HOMO) and acceptor (LUMO) moieties can be spatially separated with orthogonal orientation. On this basis, we prepared a series of novel boron complexes bearing electron deficient pyridyl pyrrolide and electron donating phenylcarbazolyl fragments or triphenylamine. The new boron complexes show strong solvent-polarity dependent charge-transfer emission accompanied by a small, non-negligible normal emission. The slim orbital overlap between HOMO and LUMO and hence the lack of electron correlation lead to a significant reduction of the energy gap between the lowest lying singlet and triplet excited states (ΔET-S) and thereby the generation of thermally activated delay fluorescence (TADF).
