CIGS-Based Thin Film Solar Cells
Our projects and research have different focuses, which can be described in how the solar cells will be used.
A typical CIGS-type solar cell.
CIGS-solceller
World record! Recently, research from our collaboration with the company Evolar (now First ETC) joined the list of world records [link to NREL and Progress in Photovoltaic record tables]. The world record is published in an article in Nature Energy.
CIGS is an acronym for Cu(In,Ga)Se2. This semiconductor material is a highly efficient light absorber. The material is self-doped and high quality CIGS materials are therefore always p-type. To use CIGS in solar cells, it needs to be combined with several other materials to make a p-n junction, to contact the solar cell and to passivate the surfaces. On top of a substrate, a back contact is coated. The CIGS layer is coated on the back contact by co-evaporation. A buffer layer is used to get an efficient PN transition and on top a transparent conductor is coated as a window layer.
Aiming for high efficiency
The research seeks to maximise the efficiency of the solar cells by using different materials, different combinations of materials and changing the manufacturing process. Our projects have different focuses, which can be described in terms of how the solar cells will be used. One area is tandem solar cells where CIGS can be part of a top cell, which should mainly absorb visible light, or as a bottom cell where the material should instead have high absorption in the infrared range. We are also working on solar cells that can be illuminated from two directions, both from the front (directly from the sun) or from the back (reflected light). To achieve high efficiency, high quality is required both in the absorbing layers and high quality in the contact layers, where the key words are long lifetime of charge carriers and high mobility.
In the transitions between different layers, the materials are required to
have the ability to conduct current, but at the same time have a low probability of recombination of the charge carriers. We are experimenting with various additives, such as silver (replacing a small amount of copper in the CIGS layer), as well as heavier alkali metals (Cs and Rb), which are added through a post-processing step to achieve low recombination.
Our CIGS research is supported by advanced characterisation methods, such as transmission electron microscopy and various types of synchrotron-based methods. We also have a theoretical part in our research with DFT methods and connection to nano-structured methods.
Kontakt: Marika Edoff
Ongoing Projects
SOLVE - Solar Electricity Research Centre, Sweden
SOLVE is a consortium of universities, colleges, institutes, companies, and organizations conducting disciplinary and interdisciplinary research in collaboration for the efficient and sustainable expansion of solar energy in Sweden.
Financier: Swedish Energy Agency, universities, colleges, RISE, and other collaborators
Project period: January 2022 – December 2026, with the possibility of a five-year extension until December 2031
Director: Marika Edoff
SITA: Stable Inorganic TAndem Solar Cells
SITA is an EU-funded project focused on developing highly efficient and stable inorganic tandem solar cells.
Project Duration: 1 September 2022 – 31 August 2025
Principal Investigator: Marika Edoff
Administrator: Ilknur Bayrak Pehlivan
Hi-BITS: High Efficiency Bifacial Thin Film Chalcogenide Solar Cells
Hi-BITS is an EU project aimed at developing high-efficiency bifacial thin film chalcogenide solar cells.
Project Duration: 1 October 2023 – 30 September 2026
Principal Investigator: Marika Edoff
Coordinator: Sascha Sadewasser, INL, Portugal
WISE PhD Student: High and Low - CIGS All Thin Film Tandem Solar Cells
This WISE PhD student project explores the development of CIGS all thin film tandem solar cells. The research is focused on achieving new levels of efficiency by combining high and low bandgap materials, enhancing the overall energy conversion process.
Project Duration: August 2022 – 2027
Responsible Researcher: Marika Edoff
PhD Student: Elizaveta Yakovleva
WISE Industrial Postdoc: Improved Flexible and Lightweight CIGS Thin Film Solar Panels
This WISE Industrial Postdoc project focuses on the development of improved flexible and lightweight CIGS thin film solar panels. In collaboration with Midsummer AB, the research aims to enhance the performance and adaptability of solar panels for diverse applications by leveraging advanced thin film technologies.
Project Duration: October 2023 – September 2025
Responsible Researchers: Marika Edoff (Uppsala University) and Esko Niemi (Midsummer AB)
Postdoc: Tanvi Upreti
WISE Postdoc: Non-toxic, Inorganic Wide Band Gap Thin Films for Tandem Solar Cells
This WISE postdoc project focuses on improving the efficiency of tandem solar cells by developing a stable and efficient top cell based on Ag-alloyed CIGS. The material is studied in both its stoichiometric and Cu-poor phases (commonly referred to as an ordered defect compound), as these phases typically create a phase mixture in solar cell materials. The properties being characterized include phase stability, film morphology, bandgap energy and band edges, conductivity type, charge carrier density, light absorption, and ion mobility of trace elements.
Project period: June 2024 – June 2026
Responsible Researchers: Charlotte Platzer Björkman and Kostiantyn Sopiha
Postdoc: Ann Maria James
Learn more
Finished Projects
Advanced Optical Concepts in ACIGS Solar Cells
This project focused on implementing advanced optical concepts in ACIGS solar cells to enhance their efficiency and performance. The research aimed to reduce environmental impact while improving energy conversion rates.
Funding: Vetenskapsrådet and Swedish Energy Agency
Project Duration: January 2021 – December 2024
Responsible Researcher: Marika Edoff
Solar Cells with Higher Efficiency and Lower Environmental Impact
In collaboration with the Swedish Energy Agency, this project worked on developing solar cells that combine higher efficiency with reduced environmental impact. The initiative aimed to push the boundaries of sustainable solar technology.
Funding: Swedish Energy Agency
Project Duration: 2020 – 2023
Responsible Researcher: Marika Edoff
Voltage Losses in Thin Film Solar Cells with Large Band Gap
This project investigated voltage losses in thin film solar cells with large band gaps, seeking to understand and mitigate efficiency losses. The research provided critical insights into optimizing the performance of these advanced solar cells.
Funding: Swedish Research Council
Project Duration: 2020 – 2023
Responsible Researcher: Charlotte Platzer Björkman
Contact: Marika Edoff
Want to read more about the research on CIGS solar cells?
Here you can read summaries of some of our scientific articles.