The field of organic photovoltaics (OPV) is a promising approach for solar cells, although it still has a long way to go, particularly in terms of efficiency and lifetime. That was the message delivered at the Organic Photovoltaics Summit, organized by the new Solar Today group and held Oct. 15-16, 2009 at Boston’s Hyatt Harborside Hotel.

Nearly 100 attendees gathered to hear about the latest breakthroughs and challenges facing the OPV field.

Day 1 Proceedings

On Oct. 15, the conference opened with remarks from Dana Olson, research scientist, National Renewable Energy Laboratory (NREL), who served as chair as well as the moderator for the opening panel discussion, “Organic Photovoltaics Market Overview.”

The panel, which examined the state of the OPV market and where it is heading was made up of Mary Boone, director of market development, Plextronics; Katherine Derbyshire, analyst, Nanomarkets; Paula Mints, senior analyst, Navigant Consulting and Johanna Schmidtke, senior analyst, Lux Research.

“I think that we can all agree that OPVs are in their infancy,” Olson noted.

“Organic photovoltaics have been in development for many years but the technology is still very young,” Mints said. “OPVs need to reach industry standards in efficiency and lifetime.”

David Germack, Polymers Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology (NIST), led the second panel, whose topic was “Improving Stability & Lifetime for Organic PV.

The members of the panel discussed the latest in OPV stability breakthroughs as well as the challenges ahead. They included Julia W. P. Hsu, member of technical staff, Sandia National Laboratories; Bernard Kippelen, associate director, Center for Organic Photonics and Electronics; Kion Norrman, senior scientist, solar energy program, Riso DTU University of Denmark – DTU; and Eitan Zeira, vice president, printed photovoltaics for Konarka.

Oxygen and water remain the major challenges in terms of degradation for OPVs.

“There are a lot of research advances for flexible barriers,” Zeira noted. “The holy grail would be a coatable barrier.” Zeira also noted that acceleration tests used for silicon may not be appropriate for OPVs.

“Improving Cell Conversion Efficiencies for Organic PV” was the topic of the third panel discussion. The session, moderated by Dr. Moritz Riede, head of the organic solar cell group, Institute for Applied Photo Physics (IAPP), analyzed OPV efficiency breakthroughs and what needs to happen on the coming years. The panel consisted of NREL’s Olson; Tom Aernouts, senior scientist, team leader OPV, IMEC; and Dr. Zheng Xu, senior researcher, Solarmer Energy.

“I think that 9 to 10 percent efficiencies is achieveable in the next few years,” Dr. Xu said.

Germack concluded the morning session with a talk on “Organic Bulk Heterojunction Interfaces: Impacts on Performance and Lifetime,” a look at the work being conducted by NIST.

“The layered structures of OPVs allow for a staggering number of potential combinations of materials,” Germack noted.

A pair of interesting discussions on commercializing OPV started off the afternoon session. Zeira discussed Konarka’s successes in his talk on “Commercial Opportunities for Printed OPV.”

“Roll to roll processing is really the answer,” Zeira said, noting that it has to be low temperature for thin film and flexible substrates. Konarka’s manufacturing facility n New Bedford, MA is capable of running at 100 square feet per minute, potentially producing 1 gigawatt per year. Konarka is presently producing its Power Plastic for applications ranging from sensors and toys to chargers and remote power systems, and is on target for BIPV (building integrated PV) projects.

Boone then discussed “Addressing Hurdles to OPV Commercialization.” She pointed out that Plextronics’ inks are achieving better than 5 percent efficiency in tests by NREL, and the company is focused on 7 percent efficiency for its inks and ink systems, which are used for OPVs and OLEDs.

Dr. Uli Wuerfel, Department Materials Research and Applied Optics, Fraunhofer ISE, followed up with “Exclusive Insight into Organic Solar Module Development at Fraunhofer ISE.” Aernouts then discussed “Research Strategies in a Developing OPV Market,” offering insight into IMEC's (Interuniversity Microelectronics Centre) OPV research on the use of multi-junction architectures.

An analysis of the financial aspects followed, as Schmidtke moderated a panel discussion on “Investors Perspectives on Organic Photovoltaics.” The panel featured John Bartlett, financial analyst, U.S. Department of Energy, and Andrew Friendly, partner, Advanced Technology Ventures.

Normann closed the first day’s program with his talk on “Water and Oxygen Induced Degradation of R2R Manufactured Polymer Solar Cells,” which offered a quantitative comparison of water and oxygen induced degradation.

Day 2 Proceedings

The second day opened with Mints, who discussed “First Applications and Markets for OPV (Looking Down the Line).” Mints talked about some of the possible opportunities, including the BIPV market.

Mints noted that the overall market for solar has grown from 1MW in 1978 to 5.5GW in 2008, although the consumer market is far smaller, with estimates of growth to 61MW by 2018.

Mints was followed by Hsu, whose topic was “Assessing Organic PV Performance and Reliability,” an evaluation of performance and reliability data for OPV. Olson then analyzed “Applications of Metal Oxides in Organic Photovoltaics,” a look at NREL’s research on indium tin oxide and other metal oxides.

Dr. Riede followed with a talk on “Efficient Organic Solar Cells Made from Small Molecules,” a look at vacuum processing and optimizing device morphology. “Organic PV Testing and Certification,” presented by Keith Emery, device performance, research staff, NREL, looked at the certification process at NREL.

Dr. Xu talked about “Current Advance in Low-Energy Gap Polymer Development and Device Engineering for OPVs,” and how this can produce high efficiencies for OPV cells. “Area-Scaling and Packaging of Organic Photovoltaic Solar Cells,” by Kippelen, closed the morning session.

The afternoon featured three talks: “Novel Organic Photovoltaics,” a look at organic compounds for scalable energy harvesting, by Max Shtein, materials science and engineering, University of Michigan; “Roll-to-Roll Manufacturing of Large Area Flexible Organic Photovoltaics Modules,” by Jukka Hast, senior research scientist, VTT Technical Research Centre of Finland; and “All-Printed Current Collecting Grid for ITO Replacement in BHJ Solar Cells,” a talk by Dr. Ronn Andriessen, program manager printing and OPV, Holst Centre/TNO.

Overall, Joshua Bull, the conference organizer, and Olson felt Organic Photovoltaics Summit went very well.

“I thought the conference was good,” said Bull. “This is an emerging sector, and there appear to be a lot of breakthroughs for this young industry. We had a good mix of developers, analysts and research institutes here.”

“The conference has gone very well,” Olson added. “There have been some good discussions.”