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Workfunction-tunable, N-doped reduced graphene transparent electrodes for high-performance polymer light-emitting
Jin Ok Hwang1, Ji Sun Park, Dong Sung Choi
1Department of Materials Science and Engineering, KI for the Nanocentury, KAIST, Daejeon, 305-701, Republic of Korea.
ACS Nano
|December 14, 2011
Summary
This study presents N-doped reduced graphene as a low-cost, high-performance alternative to fluorine-doped tin oxide (FTO) for polymer light-emitting diodes (PLEDs). The novel graphene cathode enhances device efficiency and offers tunable workfunction properties.
Area of Science:
- Materials Science
- Nanotechnology
- Organic Electronics
Background:
- Transparent conducting oxides like FTO are essential but brittle and costly.
- Reduced graphene offers a promising, cost-effective alternative with solution processability.
- Limited research has focused on reduced graphene for transparent electrode applications.
Purpose of the Study:
- To develop a workfunction-tunable, highly conductive N-doped reduced graphene film.
- To evaluate its performance as a transparent cathode in polymer light-emitting diodes (PLEDs).
- To demonstrate its advantages over traditional fluorine-doped tin oxide (FTO) electrodes.
Main Methods:
- Graphene oxide dispersion was spin-cast and subsequently treated with hydrazine and thermal reduction.
- Nitrogen doping was optimized to achieve desired workfunction and conductivity.
- Fabrication and characterization of PLEDs using N-doped reduced graphene cathodes were performed.
Main Results:
- N-doped reduced graphene films achieved a sheet resistance of 300 Ω/□ at 80% transmittance.
- This represents one of the lowest reported values for reduced graphene oxide films.
- PLEDs with N-doped graphene cathodes showed higher electroluminescence efficiency (7.0 cd/A) compared to FTO (4.0 cd/A).
Conclusions:
- N-doped reduced graphene is a viable, high-performance alternative to FTO for PLEDs.
- Tunable workfunction and reduced electron injection barriers contribute to enhanced device performance.
- Low-cost solution processing makes this graphene material attractive for flexible electronics.
