High EQE and High Brightness Solution-Processed TADF Light-Emitting Transistors and OLEDs

Viqar Ahmad, Jan Sobus, Fatima Bencheikh, Masashi Mamada, Chihaya Adachi, Shih Chun Lo, Ebinazar B. Namdas

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Thermally activated delayed fluorescence (TADF) emitters can exhibit high quantum efficiencies by harvesting triplet excitons through efficient reverse intersystem crossing. Reports on efficient TADF based light-emitting field-effect transistors (LEFETs) are rare. Moreover, despite efficient TADF organic light-emitting diodes (OLEDs), most devices have thermally evaporated multilayer device designs. In this work, highly efficient solution processed LEFETs using ACRXTN [3-(9,9-dimethylacridin-10(9H)-yl)-9H-xanthen-9-one] are demonstrated to show high external quantum efficiencies (EQEs) of ≈1% and on/off ratios (≈105) at low operating voltages (≈22 V) with negligible EQE roll-off even at ≈1,500 cd m–2. The same emitter is further studied in solution-processedOLEDs with a simple architecture to achieve high peak EQEs (≈16%) and brightness ('1000 cd m–2). The OLEDs retain a high EQE (≈10%) at 20 000 cd m–2, indicating excellent charge balance even with such simple device architecture. Our optical simulations identify EQE discrepancy in the two devices, mainly arisen from a poorer light out-coupling efficiency in the LEFETs (0.8%) than that (≈24%) in the OLEDs. This work shows state-of-the-art of solution-processed TADF LEFETs and OLEDs with simple device architectures and negligible EQE roll-off.

Original languageEnglish
Article number2000554
JournalAdvanced Optical Materials
Issue number18
Publication statusPublished - Sept 1 2020

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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