Graphene-Polymer Nanocomposite Incorporating Chemically Doped Graphene-Polymer Heterostructure for Flexible and Transparent Conductive Films
SUMMARY
UCLA researchers in the Department of Electrical Engineering have invented a novel graphene-polymer nanocomposite material for flexible transparent conductive electrode (TCE) applications.
BACKGROUND
Transparent conductive electrodes are an essential part of optoelectronics, such as light emitting diodes (LEDs), displays, and solar cells. The current TCE field is dominated by indium tin oxide (ITO) thin films because of its good stability, high conductivity, transparency, and suitable energy level. However, ITO’s brittleness limits its application in flexible and stretchable devices. As well, ITO is expensive and has a very low transmittance in the ultraviolet (UV) range (53% at 300 nm). Current alternative materials (i.e.; silver nanowires, graphene, and carbon nanotubes) have not been able to effectively replace ITO, where replacement materials must be cheap, transparent, and highly conductive to be competitive in this space.
INNOVATION
Researchers led by Professor Kang Wang have developed an innovative chemically doped graphene-polymer nanocomposite as an alternative to ITO for flexible electronic technologies. This material has a sheet resistance up to 15 ohms per square and over 90% transmittance at 550 nm, with a uniform transmittance throughout the UV-visible-near-infrared spectrum. Likewise, under an applied compressive stress there is no change in the film resistance up to 23 gigapascals and the material has a bending angle flexibility of more than ± 90 degrees.
APPLICATIONS
- TCEs for optoelectronics (i.e.; solar cells, display, and LED technologies)
- Conductive polymers and composite electrodes
- Flexible electroluminescence devices
ADVANTAGES
- Flexible and transparent electrode material
- Uniform transmittance over the UV-visible-near-infrared spectrum
- Can withstand compressive stress up to 23 GPa
- Sheet resistance up to 15 ohms/square
- ± 90 degrees bending angle
STATE OF DEVELOPMENT
Flexible doped graphene/polymer nanocomposite thin films have been fabricated and the electrical and optical properties have been characterized.