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Development and industrial implementation of cost effective advanced CIGS photovoltaic technologies

Final Report Summary - INDUCIS (Development and industrial implementation of cost effective advanced CIGS photovoltaic technologies)

With the aim to guide the transition of the society to a low-carbon future, the European Commission has launched the Strategic Energy Technology Plan (SET-Plan), which focuses, among others, on competitive solar power technologies. INDUCIS project (“Development and industrial implementation of cost effective advanced CIGS photovoltaic technologies”, www.inducis.eu ) has made a significant contribution to achieving the targets of the SET-Plan fixed for the year 2020 at European level. Scientists involved in INDUCIS have worked to develop advanced photovoltaic (PV) technologies based on electrochemical processes for the fabrication of low-cost solar cells and modules. These technologies make use of semiconductors alternative to silicon, such as CIGS (Cu(In,Ga)(S,Se)2).

Electrochemical Deposition (ED) of a precursor layer followed by a rapid thermal processing (RTP) step enables the low-cost manufacturing of high-efficiency thin-film solar cells. Applying ED in the mass production of CIGS solar modules has a great potential for reduction of manufacturing costs and fits extremely well with the requirements of the PV industry.

The main objective of INDUCIS have been the Transfer of Knowledge (ToK) and the establishment of cooperative synergies between the research and industrial worlds; a necessary step for the development and industrial implementation of PV competitive technologies. The project mission was to exploit the potential of CIGS semiconductors to achieve devices with higher efficiencies together with that of thin film technologies and ED processes for the industrial implementation of PV technologies with very low fabrication costs. Development of environmentally friendly low cost high efficiency PV technologies is an objective of special socio-economical relevance that will allow contributing to the increase in the share of renewable energies in the production of electricity in the next years in Europe. For this, a consortium formed by a research institute (IREC) and a company (NEXCIS) with strongly complementary competences and scientific background was defined.

Activities developed since the beginning of the project have allowed the achievement of the foreseen scientific objectives, in terms of device efficiency, up-scaling of the processes and development of relevant assessment methodologies and process monitoring tools that are significantly ahead from those initially planned. The main results include:
• Design and demonstration of new simple methodologies suitable for the on-line chemical assessment of CIGS based absorbers with the quantitative analysis of Ga/(In+Ga) and S/(S+Se) content ratios at the absorber surface region. These are parameters strongly relevant for the device efficiency as the chemical composition of the absorber surface region, which are determining of the absorber surface band gap and, in turn, the open circuit voltage and the photovoltaic conversion efficiency of the devices;
• Development and validation at laboratory and pilot line levels of process monitoring methodologies based in multi-wavelength excitation Raman/PL combined measurements for the selective assessment of the different layers in the window/buffer/absorber multilayer device structure;
• Development and validation at laboratory and pilot line levels of light scattering methodologies suitable for the real time in-situ monitoring of the ED process steps, including the real time Raman scattering analysis of the electrolytic baths and the real time control of the layers during the ED growth.

The deep characterisation of the processes and devices developed in the project have allowed deepening in their knowledge, contributing to their further development and optimisation, which has led to the achievement of several efficiency world records for solution - based CIGS PV devices and processes at both cell level (record certified cell efficiency of 17.3%) and module level (record certified large area (commercial size) module efficiency of 14,0%), obtaining an average module efficiency of 13.25%. This value is already comparable with those available in the market, which are typically manufactured using more complex vacuum-based processes with higher CAPEX and investment costs.

These results demonstrate the potential of ED based processes for the industrial implementation of cost-efficient CIGS PV technologies. Consolidation of the competitiveness of the European PV industry is highly required to ensure the increase of the production of electricity from renewable energies in Europe according to the 20/20/20 targets established by the European Commission and the SET-Plan. INDUCIS has also contributed to the advanced training of high level professionals who are required in Europe to keep a significant role at world level in industrial advanced PV technologies, through complementary exposure to research and industrial environments. Availability of researchers and professionals with high level competences and abilities is already identified as one of the potential bottlenecks which could condition further development in Europe of these strategic technologies.

Contact: Prof. Dr. Alejandro Pérez-Rodríguez, IREC (Catalonia Institute for Energy Research), aperezr@irec.cat www.inducis.eu