Major advance in organic solar cells

Oct 19, 2009

Professor Guillermo Bazan and a team of postgraduate researchers at UC Santa Barbara's Center for Polymers and Organic Solids (CPOS) today announced a major advance in the synthesis of organic polymers for plastic solar cells.

Bazan's team:

  • reduced reaction time by 99%, from 48 hours to 30 minutes, and
  • increased average molecular weight of the polymers by a factor of more than 3.
The reduced reaction time effectively cuts production time for the organic polymers by nearly 50%, since and purification time are approximately equal in the production process, in both laboratory and commercial environments.

The higher molecular weight of the polymers, reflecting the creation of longer chains of the polymers, has a major benefit in increasing current density in by as much as a factor of more than four. Over batches with varying average molecular weights, produced using varying combinations of the elements of the new methodology, the increase in current density was found to be approximately proportional to the increase in average molecular weight.

The methodology, detailed in a Nature Chemistry paper published online today and slated for later inclusion in the print publication, "will greatly accelerate research in this area," stated Bazan, "by making possible the rapid production of different batches of polymers for evaluation." He further noted, "We plan to take advantage of this approach both to generate new materials that will increase solar cell efficiencies and operational lifetimes, and to reevaluate previously-considered polymer structures that should exhibit much higher performance than they showed initially."

To make these gains, the team:

  1. Replaced conventional thermal heating with microwave heating,
  2. modified reactant concentrations, and
  3. varied the ratio of reactants by only 5% from the nominal 1:1 stoichiometric ratio normally employed in polymerization reactions.

Mike McGehee, Director of Stanford's Center for Advanced Molecular Photovoltaics, hailed Bazan's work, commenting, "Many synthetic chemists around the world are making copolymers with alternating donor and acceptors to attain low bandgaps. Most of them are having trouble attaining adequate molecular weight, so this new synthetic method that creates longer polymer chains is a real breakthrough. The reduction in synthesis time should also make it easier to optimize the chemical structure as the research moves forward and will ultimately reduce the manufacturing cost."

More information: Nature Chemistry paper: dx.doi.org/10.1038/NCHEM.403

Source: University of California - Santa Barbara (news : web)

Explore further: Seeing is bead-lieving: Scientists create model 'bead-spring' chains with tunable properties

add to favorites email to friend print save as pdf

Related Stories

Clicking synthetic and biological molecules together

Feb 19, 2008

Dutch researcher Joost Opsteen has developed a method to click polymers together in a controlled manner. Using this method, he can even attach proteins to nanoballs. For instance, this approach could be used to transport ...

Discovery brings organic solar cells a step closer

Jan 15, 2009

Inexpensive solar cells, vastly improved medical imaging techniques and lighter and more flexible television screens are among the potential applications envisioned for organic electronics.

Higher efficiency organic solar cell created

Jul 12, 2007

Using plastics to harvest the energy of the sun just got a significant boost in efficiency thanks to a discovery made at the Center for Polymers and Organic Solids at the University of California, Santa Barbara.

Recommended for you

Building the ideal rest stop for protons

20 hours ago

Where protons, or positive charges, decide to rest makes the difference between proceeding towards ammonia (NH3) production or not, according to scientists at Pacific Northwest National Laboratory (PNNL) and ...

Cagey material acts as alcohol factory

22 hours ago

Some chemical conversions are harder than others. Refining natural gas into an easy-to-transport, easy-to-store liquid alcohol has so far been a logistic and economic challenge. But now, a new material, designed ...

User comments : 0