标题：Magnetic field effect in organic light emitting diodes based on donor-acceptor exciplexes showing thermally activated delayed fluorescence
作者：Baniya, S.; Pang, Z.; Sun, D.; Basel, T.; Zhai, Y.; Kwon, O.; Choi, H.; Vardeny, Z. V.
作者机构：[Baniya, S.; Pang, Z.; Sun, D.; Basel, T.; Zhai, Y.; Vardeny, Z. V.] Univ Utah, Dept Phys & Astron, Salt Lake City, UT 84112 USA.; [Pang, Z.] Shando 更多
会议名称：20th Conference on Organic Light Emitting Materials and Devices
会议日期：AUG 28-30, 2016
来源：ORGANIC LIGHT EMITTING MATERIALS AND DEVICES XX
关键词：organic light-emitting diodes; thermally activated delayed fluorescence;; additive fluorescence emitters; reverse intersystem crossing;; magneto-photoluminescence; magneto-electroluminescence
摘要：A new type of organic light-emitting diode (OLED) has emerged that shows enhanced operational stability and large internal quantum efficiency approaching 100%, which is based on exciplexes in donor-acceptor (D-A) blends having thermally activated delayed fluorescence (TADF) when doped with fluorescent emitters. We have investigated magneto-electroluminescence (MEL) and magneto-conductivity in such TADF-based OLEDs, as well as magneto-photoluminescence (MPL) in thin films based on the OLEDs active layers, with various fluorescence emitters. We found that both MEL and MPL responses are thermally activated with substantially lower activation energy compared to that in the pristine undoped D-A exciplex host blend. In addition, both MPL and MEL steeply decrease with the emitters' concentration. This indicates the existence of a loss mechanism, whereby the triplet charge-transfer state in the D-A exciplex host blend may directly decay to the lowest, non-emissive triplet state of the additive fluorescent emitter molecules.