Organic solar cells push efficiency thresholds to 8.3%

Sara Ver-Bruggen - 08 Dec 2010

European and US organic solar cell developers have recorded 8.3% efficiencies for prototype devices.

The results help to increase the commercial relevance of these emerging solar cell technologies, opening up opportunities for low-cost and lightweight renewable power generation.

Heliatek, a Germany-based developer of vacuum-processed organic photovoltaic (OPV) devices, made a 1.1cm² device with efficiencies of 8.3%, independently confirmed characteristics of a PV module in development for commerc by Fraunhofer ISE CalLab in Freiburg. The cell has the sameial applications. This will comprise several individual cells connected to each other, similar to existing thin-film solar technologies.

In the US, Konarka recently followed up with its own 8.3% efficiency cell, independently verified by the National Renewable Energy Laboratory (NREL). Konarka's technology is based on a single junction solar cell structure and exceeds previous efficiency records for this type of OPV technology.

Fabrication

Both companies are developing structures and processes for fabricating flexible solar cells. Konarka's cells are produced on plastic, while Heliatek's are made on foil.

Boosting efficiencies of pre-commercial cells will help enable the companies to transfer these gains to pilot and early commercial-phase production in the next two years.

However improving conversion efficiencies of emerging solar cells is only half the challenge. For practical applications devices need to be robust and stable. To overcome this Solarmer - another US organic solar cell developer, which has recorded device efficiencies of 8.13% - is working with NREL in a cooperative R&D agreement to improve the lifetimes of plastic solar cells.

Work includes evaluating the lifetime of Solarmer's cells under simulated solar conditions that accelerate degradation of the cells, and improving the durability of OPV cells by tweaking the device architecture, and applying and testing different barrier layers.

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