Electronic properties of polymers for photovoltaic applications
DIPC Seminars
- Speaker
-
Michel Côté, Univ. Montreal, Canada
- When
-
2011/10/20
14:00 - Place
- Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
- Add to calendar
-
iCal
Organic photovoltaic devices are presently the subject of intense research
since they could propose alternative solar energy solutions. Their main
advantages are probably their reduced fabrication cost as compared to
inorganic devices and the possibility to make flexible and light weight
devices. Although devices made of organic materials such as polymers are not
as efficient as inorganic semiconductors, their performance is increasing
rapidly reaching presently close to 8%. The search for better photovoltaic
polymers is very active, and ab initio calculations can help in this pursuit
by assessing potential polymers and evaluate their value even before they are
synthesized. Of the desirable properties, the band gap is surely crucial to
improve efficiency and some candidate polymers that have better tuned optical
properties to the solar spectrum will be presented. Another important issue
for organic device is the electron transport material. Presently, electron
transport is achieved with a fullerene derivative
(PCBM) but this solution has some disadvantages. First, the ratio of PCBM to
polymer has to be quite high to assure good electronic transport, and second,
the relative high prize of PCBM is not compatible with the goal of reducing
the cost of the device. For these reasons, a replacement for PCBM is desirable
and an all polymer device solution is vie
wed as the best avenue. An essential property for a polymer to be able to
transport electrons is its electron affinity which has to be as high as
possible. We will present results of calculations of polymers that meet this
criterion. Also, we will discuss our efforts to address the problem of the
energy levels in density-functional theory calculations.