Efficient blue organic light-emitting devices with a new bipolar emitter

A new multifunctional compound, 4,4′-di-(1-pyrenyl)-4′′-[2-(9,9′-dimethylfluorene)]-triphenylamine (DPFA) has been designed, synthesized and applied respectively as host-emitter, electron- and hole-transporters in organic light-emitting devices (OLEDs). The compound exhibits good thermal stability with a glass transition temperature (Tg) of 161 °C and shows blue emissions in both solution and films. OLEDs with DPFA playing various roles have been fabricated and characterized. The results show that DPFA has efficient bipolar charge transport properties for both hole and electron. By using DPFA as a blue emitter in a typical three layer device with a configuration of ITO/NPB(50 nm)/DPFA(20 nm)/TPBI(30 nm)/LiF(0.5 nm)/MgAg, highly efficient blue emission with a maximum luminescence efficiency of 5.1 cd/A (5.3 lm/W) is obtained.

The molecular structure of the bipolar emitter; I-V-L characteristics of the device based on the bipolar emitter, inset: current and power efficiencies of the device.Figure optionsDownload as PowerPoint slideResearch highlights
► New multifunctional 4,4′-di-(1-pyrenyl)-4′′-[2-(9,9′-dimethylfluorene)]-triphenylamine (DPFA) has been designed, synthesized, and applied as host emitter, electron- and hole-transporters in organic light-emitting devices (OLEDs).
► DPFA exhibits good thermal stability with a glass transition temperature (Tg) of 161 °C and shows blue emissions in both solution and films.
► DPFA has efficient bipolar charge transport properties for both hole and electron.
► Highly efficient blue emission with a maximum luminescence efficiency of 5.1 cd/A (5.3 lm/W) is obtained in DPFA based devices.