By Cameron Chai
A team led by Bernard Kippelen of Georgia Tech has introduced a new method to decrease the work function of a broad range of conductors, including aluminum, gold and silver. They have applied an ultra-thin polymer layer of about 1-10 nm thick over the surface of the conductor to produce a strong surface dipole.
After introducing what appears to be a universal technique to reduce the work function of a conductor in printable electronics, a team led by Georgia Tech's Bernard Kippelen has developed the first completely plastic solar cell.
The application converts air-stable conductors into low-work function, efficient electrodes. The team has used commercially available polymers that can be easily produced from dilute solutions present in solvents like methoxyethanol and water. These polymer materials are environmentally friendly, economical and compatible with existing roll-to-roll mass production methods.
Printed electronics, an emerging technology, is anticipated to grow rapidly in the next 10 years. However, a major challenge lies in low-cost manufacturing of printed electronics under ambient conditions. The technology needs conductors, such as lithium, magnesium or calcium with a reduced work function to generate energy or light by infusing or collecting electrons. These conductors are chemically very reactive and they get oxidized and stop functioning when exposed to moisture and oxygen. Hence, electronics in TVs and solar cells need to be protected with a thick barrier, such as expensive encapsulation layers or glass. The new polymer modifier technique overcomes this obstacle and can lead to the development of low-cost and more flexible electronic devices.
The team has evaluated the performance of the polymers in OLEDs and organic thin-film transistors using the innovative technique. They have developed the first completely plastic solar cell. The method is also efficiently used in graphene and transparent metal-oxides, remarked Seth Marder, a professor in the School of Chemistry and Biochemistry and an associate director of COPE.