Developments Continue in Organic PV
By Tom Morrow, EVP Emerging Markets, SEMI
Oct 18, 2012
Despite the dominance of crystalline silicon products in the market today, significant commercial and research milestones continue to be reached by organic photovoltaics (OPV). Currently, OPV does not offer the efficiency levels or lifetime assurances of crystalline silicon, but OPVs can offer unique form factor advantages, low capital expenditure requirements
and low cost roll-to-roll production. At the SEMI Plastic Electronics Conference, held in Dresden Germany from October 9-11, three days of technical and business presentations dedicated to OPV reviewed the status of OPV and the near and long term expectations for the technology.
A highlight of the OPV track at the conference was a keynote presentation by Thibaud Le Séguillon, CEO of Heliatek. The company was founded in 2006 out of two leading universities in Germany, has announced the world's leading OPV efficiency of 10.7 % and successfully demonstrated R2R production in Dresden. Heliatek is backed by backed by industry (Bosch, BASF, RWE) venture capital (Wellington Partners) and has received €10 M in public funding. The company is in the process of ramping up commercial production with 75MWp capacity and expected to begin a second R2R fab in January 2013.
Heliatek is focused on four key competencies: materials development, stack architecture, roll-to-roll production, and OPV business development. The company's business development strategy is to provide energy harvesting films for a variety of end markets, not in rooftop panels. The near-term applications are for "energy to go" applications up to 2-3MW, including automotive roofs, but by 2015 they plan to fully exploit the building integrated PV market (BIPV) providing films to glass, cement, polycarbonate, membranes and other building materials. They are targeting markets that need to unique form-factor of flexible films including ease of integration, aesthetics, superior energy harvesting and truly disposable green qualities. A key differentiator for Heliatek OPV—critical to automotive and architectural applications—is transparency. Today, they achieve 6.5% at 30% light transmission with a near-term goal of 7% at 30% light transmission, then 50%.
The company utilizes small molecule organics—oligomers—rather than polymers to achieve better efficiency, lifetime performance and production reliability. Oligomers do not require solvents in production, enables the preparation of optimized multilayer tandem cells, and avoids interface degradation by adding dedicated (doped) interlayers. The product utilizes a 250 nm stack with absorber layers that requires an amazing 1 gram of material for every square meter. Their Gen 8 production line (2.2M width) has a throughout of one meter per minute.
Le Séguillon confidently explained that only a small shift in spectra (50-100nm) will enable 13% efficiencies. He sees a clear path to 15% efficiencies. The company claims superior energy harvesting, up to 25% higher yield over traditional PV. At low light, Heliatek claims 15-25% better efficiency than other PV technologies and no loss of efficiencies at low temperatures.
Heliatek's foil-encapsulated solar films withstand lifetime tests well above industry standard PV limits Using IEC testing methods, Heliatek OPV provides excellent lifetime rating, proving > 95 % efficiency after 1,800 hrs both in light soaking test and at 85 °C. Extrapolated light soaking lifetime T80: 13,600 hrs (approximately 24 yrs.).
The product is manufactured on roll-to-roll pilot line using 30 cm wide PET-substrate using linear sources with low temperature vacuum deposition. Laser scribing is used for P1, P2 and P3 structuring. One vacuum roll coater integrates organic multilayer deposition, metal deposition, P2, P3 and first encapsulation.
3-Day OPV Agenda
The SEMI Plastics Electronics Conference featured morning plenary sessions with 3-afternoon and morning tracks on OPV, Displays and Lighting, and Integrated Systems. Over 15 presentations were given on OPV organized into technology, business case, and manufacturing. In addition to sessions on current and near-term commercialization from Heliatek, Merck Chemicals, Mitsubishi Chemical, Eight19, and Isovoltaic, the latest research on OPV was presented by CEA LITEN, Holst Centre, VTT, and many others.
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