From Lab to Industrial-Scale Production: Organic PV Overcomes Scaling Hurdle

Freiburg – Organic photovoltaics has made the leap from lab-scale cells to an industry-ready manufacturing process. A research team from the University of Freiburg and the Fraunhofer Institute for Solar Energy Systems ISE, working with industry partners, has produced semitransparent organic solar modules on significantly larger areas than before.

Transferring lab results to industrially relevant module sizes has long been considered the central hurdle in organic photovoltaics: processes that deliver high efficiencies at small scale often cannot be scaled up to large-area modules without losses. For semitransparent variants, there is an additional trade-off between light transmittance and efficiency loss, a relationship the industry describes as light utilization efficiency (LUE).

43.2 Percent Transparency at Up to 9.26 Percent Efficiency

As part of the "Durchblick-PV" project, the research team produced semitransparent organic solar modules with an area of around 210 square centimeters on 14.5 by 14.5-centimeter glass substrates. The modules achieved an average visible-light transmittance of 43.2 percent and an efficiency of up to 9.26 percent, corresponding to a light utilization efficiency of up to 4.0 percent.

The near-infrared-reflecting back electrode was applied using a sputtering process. The organic absorber layer and a metal-free top electrode made of the conductive polymer PEDOT:PSS were applied via slot-die coating. More than 100 solar cells were then interconnected using laser structuring.

"The fact that we have now, for the first time, successfully and with virtually no loss applied all the layers of the solar cells using the slot-die process is a major breakthrough for us," said Dr. Uli Würfel, Head of the Organic and Perovskite Photovoltaics Department at Fraunhofer ISE.

The higher transparency of the top electrode was aided by a new PEDOT:PSS formulation from Heraeus Epurio, a specialty chemicals company based in Hanau that has long supplied conductive polymers to the electronics industry under its Clevios brand. The results were published in the journal "Joule" in August 2026.

Flexible Modules Withstand 1,275 Bending Cycles Without Efficiency Loss

Because slot-die coating is also compatible with roll-to-roll processes, the "Durchblick-PV" project also investigated and demonstrated the transfer of the technology to flexible substrates. The films required for this were supplied by ROWO Coating, a vacuum-coating specialist based in Herbolzheim, Baden-Württemberg.

"As part of the project, we have already produced the first flexible, organic PV modules that retain 100 percent of their original efficiency after 1,275 bending cycles over a rod with a diameter of 15 millimeters," said Dr. Mathias List, research associate for organic and perovskite photovoltaics at Fraunhofer ISE.

As a next step, the research team plans to increase the module area for the flexible variants as well. It cites facades and greenhouses as potential applications for high-transparency modules, and tinted applications such as vehicle roofs for variants with lower light transmittance. This makes the technology particularly relevant for building-integrated photovoltaics (BIPV) and agrivoltaics (Agri-PV).

The "Durchblick-PV" project is funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK, now BMWE). In addition to Fraunhofer ISE and the University of Freiburg, project partners included Heraeus Epurio, ROWO Coating, and Asca, a provider specializing in organic photovoltaic films.

According to Würfel, the manufacturing process is now, for the first time, sufficiently controllable to allow the team to further increase the transparency of the rigid modules and expand the area of the flexible variants in the next step, without reducing efficiency.

Source: IWR Online, 27 Aug 2026