Organic Photovoltaics

Organic photovoltaics offers unique potential for the generation of environmentally friendly electrical energy. The semiconducting materials essentially consist of hydrocarbons, ranging from small molecules to polymers. The layers of organic solar cells are around 1000 times thinner than crystalline silicon solar cells, ranging from a few nanometers for certain contact layers to several hundred nanometers for the light-absorbing layers. This makes them extremely light, flexible and unbreakable, determined solely by the packaging. Due to the low material consumption, the simple processing with printing and coating processes and the avoidance of critical elements such as lead or cadmium, the ecological footprint is extremely small.

OPV technology has the potential to further increase CO2 savings through photovoltaics and drastically reduce energy recovery times. As the materials are carbon-based, it is even conceivable in the long term to produce them synthetically from CO2, provided that such technologies, such as Power-to-X, can be established in the future. The molecularly shaped optical properties open up unrivaled adaptability, so that a wide variety of types of solar cells can be developed, from classic single-junction solar cells with efficiency potential of at least 20% (19% has already been achieved in the laboratory), to multi-junction solar cells with potential for even higher efficiencies or solar cells specially adapted to artificial light sources, to spectrally selective solar cells that are highly transparent in the visible spectral range and use UV and infrared light to generate electricity. As a result, this technology can enable innovative products such as floating photovoltaic films, electricity-generating awnings, window panes and greenhouses, particularly in integrated photovoltaics.  In the short term, initial applications as an energy source for wireless sensor technology in the areas of production, logistics and smart homes appear feasible. 

This extraordinary potential motivates us to work with our partners to tackle the existing challenges in terms of efficiency, long-term stability, scaling up to modules and production processes in a targeted and application-specific manner.

Material Screening and Cell Stack Optimization of Organic Solar Cells

Unsere exzellente Laborinfrastruktur inklusive automatisierter Basis-Charakterisierung erlaubt die schnelle Qualifikation und Parameteroptimierung. Solarzellen können sowohl vollständig unter Inertgas als auch an Luft hergestellt werden.
© Fraunhofer ISE
Our excellent laboratory infrastructure, including automated basic characterization, allows for rapid qualification and parameter optimization. Solar cells can be produced both completely under an inert gas and in air.

New organic semiconductors and contact materials are continually being synthesized all over the world. This makes continuous screening of the most promising materials indispensable. Our attention is focused not only on the highest efficiency values, but also on long-term stability and compatibility with production-relevant cell stacks and processes. The most suitable materials are identified for various applications.

Our R&D Services on this Topic Include:

  • Testing of materials and components for use in organic solar cells
  • Benchmarking in reference cell stacks
  • Development of production-relevant cell concepts

 

Organic Photovoltaics with High Visual Transparency

Laserstrukturiertes transparentes OPV-Modul.
© Laser-structured transparent OPV module.
Laser-structured transparent OPV module.

Organic photovoltaics offers a unique potential for modules with high visual transparency. Since organic semiconductors absorb only a limited bandwidth of light due to their molecular nature, Materials can be produced that strongly absorb near-infrared light but hardly any visible light. This is not possible with other technologies based on band-edge semiconductors such as silicon, inorganic thin-film materials or perovskites due to fundamental differences in the material properties. The spectral selectivity of organic semiconductors theoretically allows the production of completely transparent photovoltaics with a potential efficiency of 20%. In addition, fine laser structuring can be used to produce modules with barely visible structures. On the terawatt scale, highly transparent OPV can be used in the sections of agri-photovoltaics, building integration and e-mobility. We are working hard to exploit this potential.

Our R&D Services on this Topic Include:

  • Development of highly transparent front electrodes and optically selective rear electrodes with high transmission in the visible spectrum and high reflectivity in the near-infrared spectrum
  • Application-specific optimization of the layer stack with regard to the desired degree of transparency and the layout of modules
  • Manufacture of demonstrator modules

Module and Production Processes of Organic Photovoltaics

Mit der Rolle-zu-Rolle Beschichtungsanlage können OPV-Module teilinert oder an Luft hergestellt werden.
© Fraunhofer ISE / Foto: Thomas Klink
With the roll-to-roll coating system, OPV modules can be produced in a partially inert environment or in air.

From world-record modules produced under laboratory conditions to flexible OPV modules manufactured entirely using roll-to-roll processes, we can process modules on rigid and flexible substrates using various coating methods in air and under inert gas. Our development activities focus on scalable processes that use inexpensive and harmless materials. In this context, cell stacks, circuitry and dimensions are optimized for each specific application. For example, the optimal modules for an application under indoor lighting conditions differ significantly from those to be used outdoors. The choice of organic semiconductor material, the electrode layers and the module layout then depend on such practical differences.

Our R&D Services on the Topic Include:

  • Application-specific optimization of the module layout
  • Development of cost-effective and robust module concepts
  • Production of demonstrator modules

 

Long-Term Stability of Organic Solar Cells

Organische Solarmodule auf dem Teststand am Fraunhofer ISE.
© Fraunhofer ISE
Organic solar modules being tested at the Fraunhofer ISE.

The requirements for long-term stability and the main influencing factors depend heavily on the respective application. Various aging tests under controlled conditions (e.g. continuous illumination with simulated sunlight or LEDs, elevated temperature) and outdoors can be used to identify the crucial factors and to improve the OPV modules in a targeted manner. From small laboratory cells to OPV modules, we can precisely determine long-term stability by measuring characteristic curves and maximum power point tracking. By recording important environmental parameters, correlations can be established and behavior at different light intensities, angles of incidence and temperatures can be determined. By determining such data and conducting a thorough characterization, the decisive factors for degradation can be identified and the component stability of OPV modules improved.

Our R&D Services on this Topic Include:

 

Characterization and Modeling of Organic Solar Cells

© Fraunhofer ISE

In the long term, a thorough understanding of how organic solar cells work is crucial for the efficient further development of the technology. A wide range of characterization methods makes it possible to identify limiting factors in a targeted manner. Modeling allows hypotheses about influencing mechanisms to be tested quantitatively, thus enabling an increasingly detailed understanding to be gained. These methods also help in the section of long-term stability, both to localize weaknesses in the encapsulation and to identify degradation mechanisms.

  • Electrical simulation of components (Sentaurus TCAD)
  • Optical simulation (transfer matrix and RCWA)
  • Electro-optical characterization to identify functional principles and limiting components in the solar cells
  • Imaging techniques (thermography, spatially resolved photocurrent, electroluminescence, photoluminescence) to localize defects and optimize coatings and production processes

R&D Infrastructure

At Fraunhofer ISE, we benefit from this infrastructure for our research and development activities:

 

Center for Emerging PV Technologies

Next-generation solar cell technologies

Selected Research Projects

 

ADAPT

Climate Adaptation through Organic Agri-Photovoltaics

 

ORGANAUT

Organic Photovoltaics for Autonomous Linked Sensors and Internet of Things

Current Publications on the Topic "Organic Photovoltaics"

Jahr
Year
Titel/Autor:in
Title/Author
Publikationstyp
Publication Type
2024 Ultra-Stable ITO-Free Organic Solar Cells and Modules Processed from Non-Halogenated Solvents under Indoor Illumination
Müller, David; Jiang, Ershuai; Campos Guzmán, Laura; Rivas Lazaro, Paula; Baretzky, Clemens; Bogati, Shankar; Zimmermann, Birger; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2023 Over 1600 V DC voltage from highly efficient solar mini modules
Jiang, Ershuai; Jamali, Armin; List, Mathias; Würfel, Uli
Vortrag
Presentation
2023 Photoelectrochemical Energy Storage with Organic Solar Cells
Delgado Andrés, Rodrigo; Berestok, Taisiia; Wessling, Robin; Schyrba, Kateryna; Fischer, Anna; Esser, Birgit; Würfel, Uli
Vortrag
Presentation
2023 Improved Light Utilization Efficiency for an ITO-Free Semitransparent Organic Solar Cell Using a Multilayer Silver Back Electrode as Infrared Mirror
Pap, Leonie; Schirmacher, Bertolt; Bloch, Esther; Bogati, Shankar; Viehmann, Philipp; Scheel, Arnulf; Müller, David; List, Mathias; Zimmermann, Birger; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2023 Photoelectrochemical Energy Storage with Organic Solar Cells
Delgado Andrés, Rodrigo; Berestok, Taisiia; Weßling, Robin; Shchyrba, Kateryna; Fischer, Anna; Esser, Birgit; Würfel, Uli
Meeting Abstract
2023 Organic Solar Cell with an Active Area > 1 cm² Achieving 15.8% Certified Efficiency using Optimized VIS-NIR Antireflection Coating
Faißt, Jared; Jiang, Ershuai; Bogati, Shankar; Pap, Leonie; Zimmermann, Birger; Kroyer, Thomas; Würfel, Uli; List, Mathias
Zeitschriftenaufsatz
Journal Article
2023 Improved Current Generation for an ITO-free Semitransparent Organic Solar Cell Using a Multilayer Silver Electrode as Distributed Bragg Reflector
Pap, Leonie; Glissmann-Jahnke, Nico; Zimmermann, Birger; Würfel, Uli
Vortrag
Presentation
2023 Indoor Photovoltaics for the Internet-of-Things - A Comparison of State-of-the-Art Devices from Different Photovoltaic Technologies
Müller, David; Jiang, Ershuai; Rivas Lazaro, Paula; Baretzky, Clemens; Loukeris, Georgios; Bogati, Shankar; Paetel, Stefan; Irvine, Stuart J.C.; Olobia, Ochai; Jones, Steve; Lamb, Dan; Richter, Armin; Siefer, Gerald; Lackner, David; Helmers, Henning; Teixeira, Cristina; Forgács, David; Freitag, Marina; Bradford, David; Shen, Zhogjin; Zimmermann, Birger; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2023 Direct Determination of the Photogenerated Free Charge Carrier Luminescence in Organic Solar Cells via Transient Photoluminescence Measurements
Faißt, Jared; List, Mathias; Würfel, Uli
Vortrag
Presentation
2023 Photovoltaics on Earth vs. Space
Lackner, David; Philipps, Simon; Bett, Andreas W.
Vortrag
Presentation
2023 Organic photo-battery with high operating voltage using a multi-junction organic solar cell and an organic redox-polymer-based battery
Delgado Andrés, Rodrigo; Wessling, Robin; Büttner, Jan; Pap, Leonie; Fischer, Anna; Esser, Birgit; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2023 Determination of Free Charge Carrier Luminescence and quasi-Fermi Level Separation in Organic Solar Cells via Transient Photoluminescence Measurements
List, Mathias; Faißt, Jared; Heinz, Friedemann; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2022 A novel recycling method for encapsulated perovskite mesoscopic photovoltaic devices with minimal performance loss
Bogachuk, Dmitry; Windt, Peter van der; Martineau, David; Narbey, Stephanie; Verma, Anand; Zouhair, Salma; Hinsch, Andreas; Kohlstädt, Markus; Wagner, Lukas
Vortrag
Presentation
2022 Stability of flexible ITO-free OPV for indoor application
Müller, David; Campos Guzman, Laura; Rivas Lazaro, Paula; Jiang, Ershuai; Zimmermann, Birger; Würfel, Uli
Vortrag
Presentation
2022 ITO-Free Indoor OPV Modules from Nonhalogenated Solvents
Müller, David; Campos Guzmán, Laura; Jiang, Ershuai; Zimmermann, Birger; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2022 Stable, cost-effective, sustainable and recyclable perovskite photovoltaics using carbon-based electrodes
Bogachuk, Dmitry; Wagner, Lukas; Windt, Peter Van Der; Martineau, David; Zouhair, Salma; Hinsch, Andreas
Vortrag
Presentation
2022 Direct Determination of the Steady State and Time-Resolved Quasi-Fermi Level Separation in Organic Solar Cells from Electroluminescence Measurements
Faißt, Jared; List, Mathias; Heinz, Friedemann; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2021 ITO-Free Inverted OPV Modules from Non-Halogenated Solvents for Powering IoT Devices with Low Artificial Indoor Light
Müller, David; Campos Guzmán, L.; Jiang, E.; Zimmermann, Birger; Würfel, Uli
Vortrag
Presentation
2021 Quantifying Losses of Perovskite Solar Cells with Carbon-based Back-contacts and Outlining a Roadmap on Boosting their Power Conversion Efficiencies
Bogachuk, Dmitry; Yang, B.; Suo, J.; Martineau, D.; Verma, Anand; Narbey, S.; Anaya, M.; Frohna, K.; Müller, David; Doherty, T.; Zouhair, Salma; Herterich, Jan Philipp; Wagner, Lukas; Hagfeldt, A.; Würfel, Uli; Stranks, S.; Hinsch, Andreas
Konferenzbeitrag
Conference Paper
2021 A 1 cm2 Organic Solar Cell with 15.2% Certified Efficiency. Detailed Characterization and Identification of Optimization Potential
Würfel, Uli; Herterich, Jan Philipp; List, Mathias; Faißt, Jared; Bhuyian, F.M.; Schleiermacher, Hans-Frieder; Knupfer, Klara T.; Zimmermann, Birger
Zeitschriftenaufsatz
Journal Article
2021 Ion Movement Explains Huge Voc Increase despite Almost Unchanged Internal Quasi-Fermi-Level Splitting in Planar Perovskite Solar Cells
Herterich, Jan Philipp; Unmüssig, Moritz; Loukeris, Georgios; Kohlstädt, Markus; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2020 Visualizing Morphological Principles for Efficient Photocurrent Generation in Organic Non-Fullerene Acceptor Blends
Köntges, W.; Perkhun, P.; Kammerer, J.; Alkarsifi, R.; Würfel, Uli; Margeat, O.; Videlot-Ackermann, C.; Simon, J.-J.; Schröder, Rasmus R.; Ackermann, J.; Pfannmöller, M.
Zeitschriftenaufsatz
Journal Article
2019 ITO-Free Organic Photovoltaic Modules Based on Fluorinated Polymers Deposited from Non-Halogenated Solution: A Major Step toward Large-Scale Module Production
Ibraikulov, O.A.; Wang, J.; Kamatham, N.; Heinrich, B.; Méry, S.; Kohlstädt, Markus; Würfel, Uli; Ferry, S.; Leclerc, N.; Heiser, T.; Lévêque, P.
Zeitschriftenaufsatz
Journal Article
2019 Do Zero-Energy Building Requirements Motivate Use of Higher Efficiency Solar Cells?
Bett, Andreas W.
Vortrag
Presentation
2019 Recombination between Photogenerated and Electrode-Induced Charges Dominates the Fill Factor Losses in Optimized Organic Solar Cells
Würfel, Uli; Perdigón-Toro, L.; Kurpiers, J.; Wolff, C.M.; Caprioglio, Pietro; Rech, J.J.; Zhu, J.; Zhan, X.; You, W.; Shoaee, S.; Neher, Dieter; Stolterfoht, Martin
Zeitschriftenaufsatz
Journal Article
2018 Apparent Field-Dependence of the Charge Carrier Generation in Organic Solar Cells as a Result of (Bimolecular) Recombination
Würfel, Uli; Unmüssig, Moritz
Zeitschriftenaufsatz
Journal Article
2018 Correct determination of charge transfer state energy from luminescence spectra in organic solar cells
List, Mathias; Sarkar, T.; Perkhun, P.; Ackermann, J.; Luo, C.; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2018 Trends in Solar Electricity
Bett, Andreas W.
Vortrag
Presentation
2018 Electron-selective contacts via ulta-thin organic interface dipoles for silicon organic heterojunction solar cells
Reichel, Christian; Würfel, Uli; Winkler, Kristina; Schleiermacher, Hans-Frieder; Kohlstädt, Markus; Unmüssig, Moritz; Meßmer, Christoph Alexander; Hermle, Martin; Glunz, Stefan W.
Zeitschriftenaufsatz
Journal Article
2018 Silicon-Organic Heterojunction Solar Cells with Electron-Selective Contacts Based on Organic Interface Dipoles
Reichel, Christian; Würfel, Uli; Winkler, K.; Schleiermacher, Hans-Frieder; Kohlstädt, Markus; Unmüssig, Moritz; Meßmer, Christoph Alexander; Hermle, Martin; Glunz, Stefan W.
Konferenzbeitrag
Conference Paper
2017 Luminescence spectroscopy and thin-film interference effects in organic solar cells
List, Mathias; Reinhardt, Y.J.; Würfel, Uli
Vortrag
Presentation
2017 Organic solar cells: Extraction of physical parameters by means of markov chain Monte Carlo techniques
Raba, A.; Leroy, Y.; Kohlstädt, Markus; Würfel, Uli; Cordan, A.-S.
Zeitschriftenaufsatz
Journal Article
2017 On the impact of contact selectivity and charge transport on the open-circuit voltage of organic solar cells
Spies, Annika; List, Mathias; Sarkar, T.; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2017 Positive side of disorder: Statistical fluorene-carbazole-TTBTBTT terpolymers show improved optoelectronic and photovoltaic properties compared to the regioregular structures
Akkuratov, A.; Mühlbach, S.; Susarova, D.K.; Seßler, Martin; Zimmermann, Birger; Razumov, V.F.; Würfel, Uli; Troshin, P.A.
Zeitschriftenaufsatz
Journal Article
2016 Impact of charge carrier transport and electrode selectivity on the performance of organic solar cells
Würfel, Uli; Spies, Annika; List, Mathias; Kohlstädt, Markus
Vortrag
Presentation
2016 Charge carrier selectivity for contacts for organic solar cells
Spies, Annika; List, Mathias; Sarkar, T.; Würfel, Uli
Konferenzbeitrag
Conference Paper
2016 Laser patterning of vacuum processed small molecular weight organic photovoltaics
Röttinger, S.; Schwarz, B.; Schäfer, Stefan; Gauch, R.; Zimmermann, Birger; Würfel, Uli
Zeitschriftenaufsatz
Journal Article
2016 How molecules with dipole moments enhance the selectivity of electrodes in organic solar cells - a combined experimental and theoretical approach
Würfel, Uli; Seßler, Martin; Unmüssig, Moritz; Hofmann, N.; List, Mathias; Mankel, E.; Mayer, T.; Reiter, G.; Bubendorff, J.-L.; Simon, L.; Kohlstädt, Markus
Zeitschriftenaufsatz
Journal Article
2016 Impact of charge carrier transport and electrode selectivity on the performance of (organic) solar cells
Würfel, Uli; Spies, Annika; List, Mathias; Kohlstädt, Markus
Vortrag
Presentation
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