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Using solar energy to give new functions to a wide range of products

Thin Film PV

Published on 6 October 2016

Crystalline silicon is currently the primary material for volume photovoltaic solar panel production on the global market. However, other technologies suitable for niche applications do exist. Copper indium gallium selenide (CIGS) and copper zinc tin sulfide (CZTS) solar cells can, for example, overcome certain challenges when integrating PV cells onto some types of materials. The advantage lies in the fact that CIGS and CZTS can be deposited in thin layers onto objects and materials—whether rigid or flexible—not originally designed to produce energy. The resulting integrated PV capabilities can make any object self-powering, adding value to the end product.

At Liten, we have made inorganic thin-layer technologies for photovoltaic applications one of the institute’s key research areas, with the goal of developing solutions for:

  • Construction (thin-layer solutions for building-integrated photovoltaics)
  • Textiles (integrated PV cells in thread used to weave fabrics for the home, public buildings, and greenhouses)

Various Liten research projects are looking at thin-layer technologies at different stages of maturity. The earlier-stage research is generally conducted under EU research projects, while later-stage projects are usually completed in partnership with manufacturers on specific products for rapid go-to-market. The broad spectrum covered by Liten research—backed by our recognized know-how in materials—positions the institute to study thin-layer technologies in-depth, taking into account all the processes used in the fabrication and integration of solar cells.

Our research covers the two crucial building blocks of thin-layer PV cell production: light-absorbing materials—mainly CIGS and CZTS—and transparent conducting oxides (TCOs). While thin-layer PV yields, at 12% to 20%, are lower than those of crystalline silicon, thin-layer cells do open the door to flexible, lightweight PV modules and the integration of PV capabilities onto different materials and objects, two advantages that make the technology particularly attractive.


Research and testing for a wide range of industrial R&D projects

  • Thin-layer solar cells can be integrated onto a broad array of materials, even flexible ones. Our fabrication and characterization capabilities can be used to produce reduced-scale (15 cm x 15 cm) test modules on any type of substrate.
  • We can structure the layer deposition for each individual project. This flexibility lets our partners experiment with transparent finishes, especially important for PV-enabled window glass, for example.
  • Our capabilities include material reliability testing and lifespan assessments, crucial for building-integrated PV and other integrated PV applications.

  • In 2014, we completed proof-of-concept testing on a PV-enabled thread for textile applications. A functional PV coating leveraging inorganic thin-layer technology was deposited on the threads, which are suitable for both wovens and knits. The purpose is to integrate PV capabilities into products like awnings, greenhouses, and backpacks, without altering their appearance, features, and performance. This research was carried out under the multi-partner SOL-TEX project, coordinated by SunPartner Technologies. A patent application for the solar thread has been filed.
  • We developed semi-transparent PV window glass in partnership with southern-France-based company Crosslux.
  • We worked with two companies, Alliance Concept and Annealsys, to develop a thin-layer deposition machine for PV applications. The research was part of the Pro-CIGS project coordinated by the Tenerrdis energy cluster.
  • We participated in the EU Scalenano project, conducting research on cadmium-free alternatives to the CdS buffer layer, with the goal of eliminating the toxic metal altogether.
  • We contributed to the development of new-generation transparent electrodes in research conducted under the EU Mujulima and Graphene Flagship projects.
  • We contributed to surface-structuring research for optical trapping enhancement under the EU Agatha project.
  • We have also done optical modeling for a vast array of projects, both with other research institutes and with manufacturers.
  • Around 10 researchers
  • Around 20 patents
  • ​Publications:
Grenet L, Grondin P, Coumert K, Karst N, Emieux F, Roux F, Fillon R, Altamura G, Fournier H, Faucherand P, Perraud S. August 2014. Experimental evidence of light soaking effect in Cd-free Cu2ZnSn(S,Se)4-based solar cells. Thin Solid Films 564: 375.
Grenet L, Fillon R, Altamura G, Fournier H, Emieux F, Perraud S. July 2014. Analysis of photovoltaic properties of CZTSSe-based solar cells. Solar Energy Materials and Solar Cells 126: 135.
Roger C, Altamura G, Emieux F, Sicardy O, Roux F, Fillon R, Faucherand P, Karst N, Fournier H, Grenet L, Ducroquet F, Brioude A, Perraud S. November 2014. Sodium-doped Mo Back Contacts for Cu(In,Ga)Se2 solar cells on Metallic Substrates: Growth, Morphology and Sodium Diffusion. Journal of Renewable and Sustainable Energy 6: 011405.
Altamura G, Grenet L, Roger C, Roux F, Reita V, Fillon R, Fournier H, Perraud S, Mariette H. November 2014. Alternative back contacts in kesterite Cu2ZnSn(S1-xSex)4 solar cells. Journal of Renewable and Sustainable Energy 6: 011401.
Altamura G, Grenet L, Bougerol C, Robin E, Kohen D, Fournier H, Brioude A, Perraud S, Mariette H. March 5, 2014. Influence of the Precursors Stacking Order in the Selenization Process of Cu2ZnSn(S1-xSex)4 Thin Films for Photovoltaic Applications. Journal of Alloys and Compounds 588: 310.
Roger C, Noel S, Sicardy O, Faucherand P, Fournier H, Roux F,  Ducroquet F, Brioude A, Perraud S. January 31, 2014. Molybdenum-based bilayer back contacts for CIGS solar cells on metallic substrates. Thin Solid Films 548: 608.
Roux F et al., August 2013. Chalcopyrite thin-film solar cells by industry-compatible ink-based process. Solar Energy Materials and Solar Cells 115: 86.
Grenet L, Bernardi S, Kohen D, Lepoittevin C, Noël S, Karst N, Brioude A, Perraud S, Mariette H. June 2012. Cu2ZnSn(S1-xSex)4 based solar cell produced by selenization of vacuum deposited precursors. Solar Energy Materials and Solar Cells 101: 11.

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