Organic solar cell with inverted architecture achieves 8.3 percent efficiency

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The group has recorded the efficiency on its polymer-based single junction organic solar cells in an inverted device stack. "These excellent performance results represent a crucial step towards successful commercialization of organic photovoltaic cells," said Imec in a statement released.

The company has designed a proprietary inverted bulk heterojunction architecture for polymer-based solar cells, which is said to simultaneously optimize cell light management and increase device stability. "With this architecture, and a proprietary Polyera semiconductor in the photoactive layer, a team of imec and Solvay researchers now announces a certified conversion efficiency of 8.3 percent," continued the statement.

Before the technology can be commercialized, however, Imec does admit that further efficiency gains and lifetime improvements need to be recorded.

Overall, the company believes that organic cells will help to boost the cost competitiveness of solar, due to their potential to be manufactured on large-areas at high-throughput. Furthermore, their flexibility in application – they can be manufactured on such lightweight and flexible substrates as plastic and textiles – means transportation and installation costs can continue to be driven down.

Tom Aernouts of Imec tells pv magazine that organic solar cells possess the potential to beecome "the most cost-competitive PV-technology on the longer run with targets quite below 0.5 Euro/Wp."

When asked what makes this technology better than, for example, Konarka’s or Solarmer’s, which have already acheievd organic solar cell efficiencies of over eight percent last year, he replied, "We have used a reverse solar cell architecture, which means a solution-processed cathode as first layer. Such cell has better manufacturability, because we do not have a low-workfunction metal cathode (such as Ca, Li, Be, Yb, Cs or other such difficult materials, which are reputed to be highly prone to oxidation!).

"Many groups work on such architecture, but we now have the record of 8.3 percent. So, the better manufacturability in combination with avoiding sensitive materials is a strong advantage over others."