Organic photovoltaics offer greener benefits to provide solar cell

January 10, 2012 // By Paul Buckley
In this news analysis article EE Times Europe Power Management's editor, Paul Buckley quizzes Dr. Martin Pfeiffer, co-founder and CTO of Heliatek GmbH, a global leader and Heliatek's CEO, Thibaud Le Seguillon, to learn more about the high-end solar PV technology company's pioneering developments which continue to break world efficiency records in the field of organic photovoltaics and recently earned some of the company's technologists to clinch the 2011 Deutscher Zukunftspreis (German Prize for Innovation and Technology).

Last month Heliatek GmbH claimed a new world record for organic solar cells after Fraunhofer ISE CalLab (Freiburg, Germany) measured and certified under standard test conditions a cell efficiency of 9.8 % for a 1.1 cm² tandem cell manufactured with a low temperature deposition process. The new record is the third time in a row that Heliatek has set a world record for efficiency in the field of organic photovoltaics.

EE Times Europe:  Can you explain more about the recent efficiency record and the benefits of the OPV technology?

Dr. Pfeiffer:  Heliatek is the only solar company in the world focused on the deposition of small molecules with low temperature processes, a method that has already been widely adopted by the market for use with organic LEDs (OLEDs). Heliatek develops and synthesizes in-house the molecules responsible for capturing light in solar cells and converting this light into electricity.

Our latest record is 9.8 percent with a completely low temperature process organic solar cell.  The process is below 120 degrees C which is to say that it is completely compatible with cost effective PET- foil.  We don't require any highly temperature stable foils like PEN or polyimide.

The technology does not make use of any solvents.  It is a dry process in vacuum and requires the minimum consumption of organic materials as the semiconductor.  We only require a gram per square meter.  The technology uses an abundantly available non-toxic material. 

Our cells do not lose efficiency when you go up in temperature and they also do not lose efficiency when you go down in light intensity which contrasts favorably with typical silicon or Cd-Te solar cells.  These factors translate into an improved 'harvesting factor' which is how much energy you expect to gain from a nominal power.  Our 'harvesting factor' is some 10 to 20 percent better than the competition depending where you put your solar cells.

Our benchmark is Cd-Te