Concepedia

Organic Light-Emitting Diodes on Solution-Processed Graphene Transparent Electrodes

Junbo Wu, Mukul Agrawal, Héctor A. Becerril, Zhenan Bao, Zunfeng Liu, Yongsheng Chen, Peter Peumans

ACS Nano · 2009 · 967 citations · 52 references

TL;DR

Graphene thin films offer an unmatched combination of low sheet resistance and high transparency, making them attractive as transparent electrodes for thin‑film devices such as solar cells and OLEDs. This study demonstrates OLEDs fabricated with solution‑processed graphene thin‑film transparent conductive anodes. Graphene electrodes were spin‑coated from an aqueous dispersion of functionalized graphene onto quartz substrates and then vacuum‑annealed to reduce sheet resistance. Devices with small‑molecule organic layers and a metal cathode deposited directly on the graphene anodes achieved performance and outcoupling efficiency comparable to control devices on indium‑tin‑oxide anodes, confirming model predictions.

Abstract

Theoretical estimates indicate that graphene thin films can be used as transparent electrodes for thin-film devices such as solar cells and organic light-emitting diodes, with an unmatched combination of sheet resistance and transparency. We demonstrate organic light-emitting diodes with solution-processed graphene thin film transparent conductive anodes. The graphene electrodes were deposited on quartz substrates by spin-coating of an aqueous dispersion of functionalized graphene, followed by a vacuum anneal step to reduce the sheet resistance. Small molecular weight organic materials and a metal cathode were directly deposited on the graphene anodes, resulting in devices with a performance comparable to control devices on indium−tin-oxide transparent anodes. The outcoupling efficiency of devices on graphene and indium−tin-oxide is nearly identical, in agreement with model predictions.