While solar cells based on organic materials are more expensive than traditional silicon-based ones and significantly less efficient, they do have some advantages. They can be manufactured as flexible films, suitable for many surfaces without intricate mounting frames, and can make efficient use of low light conditions. New developments even indicate that the overall efficiency has the potential to rise into the area of anorganic cells.
Heliatek uses a family of small organic molecules - oligomers - developed and synthesized at its own lab in Ulm, Germany. Dr. Martin Pfeiffer, co-founder and CTO of Heliatek, brags a tiny little bit: »Heliatek is the only solar company in the world that uses the deposition of small organic molecules in a low temperature, roll-to-roll vacuum process. Our solar tandem cells are made of nanometers thin layers of high purity and uniformity. This enables us to literally engineer the cell architecture to systematically improve efficiency and lifetime.«
The measurement campaign of SGS included efficiency measurements under standard testing conditions of the solar industry as well as performance measurements at low light and high temperatures of up to 80°C.
The measurement results for low light established that the efficiency not only remains constant, but even increases gradually. At an irradiation of 100 W/m2 the efficiency is 15% higher compared to the standard efficiency measured at 1,000 W/m2. Additionally, the measurements at high temperatures confirmed that the efficiency remains constant. This behavior is unique for OPV technology in contrast to traditional solar technology which efficiency drops 15% to 20% at elevated temperatures.
These technology advantages translate into a higher harvesting factor under real life conditions. First outdoor tests have shown that the harvesting factor of Heliatek's organic solar cells is 15% to 25% higher than crystalline and thin film solar.
»When Heliatek was founded in 2006, the technology roadmap set out ambitious milestones for efficiency, and yet we have hit every single one of them,« says Thibaud Le Séguillon, CEO of Heliatek. »Thanks to the close cooperation between our research teams in chemistry and physics, we are now on our path to achieving 15 % efficiency within the next few years.«
Heliatek is currently working on its first roll-to-roll manufacturing line installed in Dresden, Germany, to go in production in the third quarter of 2012. It has also kicked off a third financing round to raise €60 million from current and new investors for a new roll-to-roll 75 MWp production line.