Originally published February 6 2006
Scientists in North Carolina reach important mark in the development of spray-on polymer solar cells
by Mike Adams, the Health Ranger, NaturalNews Editor
Professor David Caroll of Wake Forest University has announced that his team of researchers has hit a mark of six percent efficiency with spray-on polymer solar cells.
Researchers in the US have improved the efficiency of a 'spray-on' polymer-based solar cell which moves it closer to practical use.
The North Carolina scientists have hit six per cent efficiency in buckyball-doped polymer solar cells.
"We have developed a photovoltaic which is flexible and has a high efficiency," Professor David Carroll...
... of Wake Forest University told Electronics Weekly.
"It is just like paint, you just paint it on," said Carroll.
High efficiency is a relative term, Carroll pointed out.
His cells are close to six per cent efficient: double that of similar cells, but low-cost glass substrate amorphous silicon cells achieve 12 per cent.
Starting with a flexible polycarbonate substrate, Wake Forest sputters on ITO (indium tin oxide), spins on the active layer, then tops it off by depositing a thin metal contact.
"The electrons leave through the metal and the holes leave through the ITO," said Carroll.
This thing can be rolled up and taken anywhere you want."
Electron-hole separation in the Wake Forest cells occurs in a polymer layer doped with a fullerene - a compound including C60 buckyballs.
There is no junction as such in this kind of cell, instead C60 acts as an electron-acceptor through the bulk of the polymer layer, splitting up photon-induced excitons.
Crucial to the increase in efficiency at Wake Forest is a novel heat treatment.
"We flash-anneal this device by putting a temperature gradient across the material," said Carroll.
"The nano-phase material begins to form elongated crystals.
We get nano-material 0.8nm across, but in a structure hundreds of nanometres across."
Research teams across the globe are working on C60-doped solar cells.
In particular two University of California campuses: Santa Barbara and UCLA, are in friendly rivalry with Carroll.
All content posted on this site is commentary or opinion and is protected under Free Speech. Truth Publishing LLC takes sole responsibility for all content. Truth Publishing sells no hard products and earns no money from the recommendation of products. NaturalNews.com is presented for educational and commentary purposes only and should not be construed as professional advice from any licensed practitioner. Truth Publishing assumes no responsibility for the use or misuse of this material. For the full terms of usage of this material, visit www.NaturalNews.com/terms.shtml