Plextronics, a Pittsburgh-based start-up developing organic photovoltaic technology for solar power, said it has raised $20.6 million in a second round of financing.

The round was led by the Solvay Group, a Brussels-based chemical-pharma group, and included Firelake Capital Management, Birchmere Ventures, Draper Triangle Ventures and Newlin Investment Company. Plextronics has raised a total of $37 million in equity capital over the last five years.

The company specializes in “printed electronics,” a field that covers next-generation light technologies (organic LEDs), flexible displays, plastic solar cells and organic RFID tags. The company is active in each of these lines. It says the market for printed electronics was about $1 billion in 2006 and is expected to exceed $300 billion within 20 years.
The company says its organic solar cells are getting efficiency rates of five percent in lab testing (referring to the efficiency with which the sun is converted into energy), which is high among organic photovoltaic competitors, but lower than other competing photovoltaic technologies, such as those based on crystalline silicon. The hope is that organic solar cells are cheaper to manufacture.