Dresden-headquartered Heliatek has set a new efficiency record of 10.7% efficiency for its tandem organic photovoltaic (PV) cell.
Accredited and independent testing facility SGS, carried out the tests on the 1.1cm2 cell under standard testing conditions of the solar industry.
Of more critical significance is the data measured concerning the OPV's performance in low light and temperatures of up to 80°C, where the efficiencies of conventional crystalline silicon panels start to drop by 15-20% at higher temperatures. Efficiency of Heliatek's cell remained constant.
Peak efficiency - widely used in the PV industry, where crystalline silicon panels account for 85% of the market - is not the only performance benchmark, however. Tests on other lighting conditions can give a more accurate sense of how OPVs perform in real-world conditions.
Low light measurement showed efficiency remains constant, but increases gradually. At an irradiation of 100W per square metre the efficiency is 15 % higher, compared to the standard efficiency measured at 1,000W/m².
First outdoor tests have shown that the harvesting factor of Heliatek's organic solar cells is 15-25 % higher than crystalline and thin-film solar.
Solar tandem cells are made up of active layers of high purity and uniformity, each a few nanometres in thickness. The structures provide scope to engineer cell architecture to steadily improve efficiency and lifetime. Heliatek's ongoing R&D work is focused on 15% efficiency in the next few years.
The company's existing roll-to-roll line will go into production in Q3 2012. Heliatek has also started a third financing round, to raise €60 million from current and new investors for a new roll-to-roll line, with an annual output of 75MW peak.
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Documents and links
Website for the TU Dresden start-up that is developing OPVs
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