Germany Develops Semi-Transparent Organic Photovoltaic Module with 9.26% Efficiency

en.Wedoany.com Reported - The Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) and the University of Freiburg have announced research results on semi-transparent organic photovoltaic modules. Using processes suitable for scalable manufacturing, the research team produced organic photovoltaic modules measuring 14.5 cm × 14.5 cm with an area of approximately 210 cm². The modules achieved an average transparency of 43.2% and a maximum power conversion efficiency of 9.26%. The findings have been published in Joule.

The research team combined magnetron sputtering with slot-die coating for module fabrication, both of which are already established in industrial applications and can be scaled to larger-area modules. The photovoltaic active layer was prepared via slot-die coating using a non-halogenated solvent system, reducing reliance on special solvents and laboratory deposition methods when transitioning from small-area lab-scale devices to continuous, large-area production processes.

The semi-transparent modules fabricated in the study achieved a maximum visible light transmittance of approximately 50%. The highest light utilization efficiency (LUE) reported in the paper reached approximately 4%, a metric used to simultaneously assess the device's power generation efficiency and visible light transmittance. By tuning the organic semiconductor absorber layers and transparent electrodes, the research team enabled the modules to primarily absorb in the near-infrared range while maintaining a relatively high proportion of visible light transmission.

In addition to rigid modules, the team validated the same manufacturing approach on flexible substrates. The flexible modules showed no performance degradation after 1,275 bending cycles around a test mandrel with a diameter of approximately 15 mm. The researchers also employed lock-in thermography and electroluminescence imaging to detect localized shunts and defects introduced during scale-up manufacturing, helping to identify areas that affect performance uniformity across large-area modules.

Fraunhofer ISE explicitly positions this technology for building-integrated photovoltaics and agrivoltaics — applications that require light transmittance. The currently published results remain at the stage of module development and manufacturing process validation; no details have been disclosed regarding commercial mass-production lines, production capacity, mass-production timelines, or product certification plans.