Boosting European competitiveness in photovoltaic solar power

Thin film solar cell technologies have a potential to offer a higher material utilization and lower module costs compared to classical wafer-based silicon solar cells because they employ light-absorbing materials that are about 100-times thinner than silicon wafers. Devices based on the substance class of chalcogenides, such as copper indium gallium (di)selenide (also known as CIGS), exhibit the highest efficiencies of all thin film photovoltaic technologies and have already entered the stage of mass production. However, current production methods typically rely on vacuum-based deposition processes that are difficult to control over large surfaces and require expensive equipment. This counteracts the potential reduction of material costs that are inherent to thin film technologies.

To take up this challenge, the EU-funded international project SCALENANO ("Development and scale-up of nanostructure-based materials and processes for low-cost, high-efficiency chalcogenide-based photovoltaics") – which runs until mid-2015 – will develop alternative, vacuum-free processes based on the electro-deposition of nanostructured precursors. The project also includes the exploration and development of alternative processes with high-throughput and process rates, as well as their extension to the next generation of Cu2ZnSn(S,Se)2-based absorbers (so-called kesterites) that only use cheap and abundant elements. Altogether, this should be a strong boost for European competitiveness in photovoltaic technologies.

Empa’s laboratory for Thin Films and Photovoltaics, led by Ayodhya Tiwari, will contribute to the project by investigating solution- and nanoparticle-based deposition of kesterite absorbers, front electrical contacts of transparent conducting oxides (TCOs) and supplying reference solar cells prepared by vacuum-based techniques. Project leader Yaroslav Romanyuk anticipates that "SCALENANO findings may find applications not only in photovoltaics but also in other fields such as smart windows and batteries."

Empa as a Swiss Materials Science and Technology Institution within the ETH domain is part of the Swiss Science-Technology-Education community. It specializes in applied research and development as well as sophisticated services in the field of sustainable materials science and technology. Its core activities are innovative collaboration with industry and public institutions to ensure the safety of humankind and the environment, knowledge propagation and university-level teaching. The Empa Academy disseminates the latest results of our work at events and in publications. The focal points of our activities are: modern materials, their surfaces and interfaces, construction materials and systems, materials and systems that protect the human body and ensure its wellbeing, information, simulation and reliability technology, and mobility, energy and the environment. Approximately 820 employees work in over 30 specialist fields in nationally and internationally funded research programs, partnership-based development projects and interdisciplinary customer-specific service assignments.

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