High Performance p- and n-Type Light-Emitting Field-Effect Transistors Employing Thermally Activated Delayed Fluorescence

Jan Sobus, Fatima Bencheikh, Masashi Mamada, Robert Wawrzinek, Jean Charles Maurice Ribierre, Chihaya Adachi, Shih Chun Lo, Ebinazar B. Namdas

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Light-emitting field-effect transistors (LEFETs) are an emerging type of devices that combine light-emitting properties with logical switching function. One of the factors limiting their efficiency stems from the spin statistics of electrically generated excitons. Only 25% of them, short lived singlet states, are capable of light emission, with the other 75% being long lived triplet states that are wasted as heat due to spin-forbidden processes. Traditionally, the way to overcome this limitation is to use phosphorescent materials as additional emission channel harnessing the triplet excitons. Here, an alternative strategy for triplet usage in LEFETs in the form of thermally activated delayed fluorescence (TADF) is presented. Devices employing a TADF capable material, 4CzIPN (2,4,5,6-tetra[9H-carbazol-9-yl]isophthalonitrile), in both n-type and p-type configurations are shown. They manifest excellent electrical characteristics, consistent brightness in the range of 100–1,000 cd m-2 and external quantum efficiency (EQE) of up to 0.1%, which is comparable to the equivalent organic light-emitting diode (OLED) based on the same materials. Simulation identifies the poor light out-coupling as the main reason for lower than expected EQEs. Transmission measurements show it can be partially alleviated using a more transparent top contact, however more structural optimization is needed to tap the full potential of the device.

Original languageEnglish
Article number1800340
JournalAdvanced Functional Materials
Volume28
Issue number28
DOIs
Publication statusPublished - Jul 11 2018

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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