We demonstrate a hybrid light-emitting device (LED) employing a chemical-vapor-deposition grown, centimeter-scale monolayer of WS2 (mWS2) as the active luminescent material embedded within conductive organic layers. The active area of the hybrid LED is composed of mWS2, located within the organic host matrix, sandwiched between the hole- and electron-transporting organic layers. The mWS2 shows fast exciton decay and efficient light outcoupling compared to the organic dyes used for OLEDs, whereas organic layers enable a precisely controlled, large-area fabrication process. As a result, LEDs with an average external quantum efficiency of 0.3 ± 0.3% and with the highest efficiency of 1% were achieved. Also, we show that negatively charged excitons, also known as trions, are generated in the mWS2 with the injected current, causing an efficiency roll-off at high current densities. Our result introduces a means for incorporating a range of emissive inorganic thin films into an organic device structure, thereby taking advantage of the positive attributes of both material systems.
Bibliographical noteFunding Information:
The work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, award no. DE-SC0017971, the Army Research Office (ARO), award no. W911NF-17-1-0312 (theory, data analysis, experimental details), and Universal Display Corporation (LED engineering). The authors thank the Lurie Nano Fabrication Facility for device processing.
© 2021 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering