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Development of nano-structured, hybrid and flexible high efficiency and low cost solar cells.

To develop photovoltaic solar modules and production processes for: *large area/low cost innovative nano-structured si pin devices increasing efficiencies from 7 to above 10%; *hybrid junctions to take efficiencies further and gain other product characteristics like transparency; *flexible pv.

One of the main problems of the use of amorphous hydrogenated silicon (a-Si:H) for PV (Photovoltaic) applications is its meta-stability which, in today’s commercial modules, results in a decrease of module efficiency in the first 100 hours of usage by 10-30%. We introduced an innovative material called nano-structured silicon (ns-Si:H), in which nano-metric silicon clusters are surrounded by an more ordered amorphous matrix (compared with a-Si:H). This new material, produced by plasma enhanced chemical vapour deposition under conditions close to powder formation, using high deposition pressures (around 5-10 mba) and hydrogen dilutions (higher than 80%) combines the high absorption of a-Si:H with the improved transport properties of microcrystalline silicon. Moreover, the superiority of ns-Si:H films over a- Si:H is maintained after light-soaking tests. Preliminary solar cells have proven the potential of this new material: on small areas stable efficiencies of 10% were reached in single junction p-i-n solar cells. Apparently the Staebler-Wronski effect is heavily reduced in this new material. Apart from that, the project aims to develop stacked cells, based on the micro-morph concept where the bottom pin solar cell is microcrystalline and the top one (one or two) is engineered nano-structured pin silicon, where it is expected to reach efficiencies of more than 12% and a light degradation effect less than 4%. These achievements correspond to overall device improvement above 50% of the in-house technology used today. Apart from that, the project seeks to promote disruptions in the field by introducing the concept of p-n hetero-junction based on p-type crystalline silicon and n-type oxides, able to reach efficiencies over 14-18%, in areas above 100 cm2. This project aims to explore the large-scale application of single and tandem ns-Si:H using environmentally sustainable production technologies. The know-how to be acquired to this end will also contribute to enhancing the production yield. The general aim of the project consists in the development of industrially applicable production techniques for solar cells using nano-structured silicon with stable efficiencies above 10%, exploring in-line batch (rigid substrates) as well as continuous roll-to-roll techniques (flexible/polymer), to ultimately obtain a system cost of less than 1 Euro/Watt-peak (1Euro/Wp). The module manufacturing cost (1,200cm x 60cm) reduction aimed at will be reached by simultaneously increasing the photovoltaic efficiency, improving the production yield, increasing the feedstock utilisation efficiency, and decreasing the cost of ownership by enhancing the growth rate. In this project we will cover the two mainstreams of production technology: in-line batch processing and continuous roll-to-roll processing. On the one hand, the inline batch process allows for fast progress since the technology is mature. On the other hand, the continuous roll-to-roll process offers a perspective to dramatically reduce production costs, but it requires much more process development time. In both cases, the projected improvements will be obtained in existing deposition hardware, where only the operational protocols and the configuration will be modified. This modification will be controlled by applying robust plasma process monitors, which will be developed and calibrated during the project. A third goal is the development of p-n hetero-junction solar cells, based on the CENIMAT achievements, in developing n-type oxide semiconductors and preliminary results of 14% efficiencies in 2cm2. Specific scientific/technical objectives to achieve are: * Laboratory-scale production of ns-Si:H solar cells with a stable PV efficiency exceeding 10%; Production at a laboratory scale p-n hetero-junction with areas larger than 100cm2 with efficiencies more than 14%. New robust process monitor techniques, calibrated against new advanced plasma diagnostics; Successful transfer of both laboratory-scale deposition technology and process monitors to the in-line batch as well as the continuous roll-to-roll pilot lines. * Production of 1,200 * 60 cm micro/ns-Si modules in a batch pilot line, envisaging a future up-scaled production facility; Production of 30 cm width, continuous length ns-Si solar cells on flexible substrates in a roll-to-roll pilot line. This will provide the know-how which will be required for achieving substantially reduced production costs per Wp in a next-generation upscaled 120 cm wide roll-to-roll production facility. There will be assessment of the economic and ecological benefits which are the results of the introduction of the new materials, devices and production techniques; in addition to the creation of the technological and scientific foundation for further improvements after conclusion of the project, based on the new materials, process monitoring techniques, and process expertise acquired in this project. This will be of benefit for both industry and academia, and may have an impact where this technology is used for other applications like TFT-LCD (Thin Film Transistor - Liquid Crystal Display), IC technology, sensors, etc.
Acronym: 
NANOSI-PVCELLS
Project ID: 
4 937
Start date: 
01-06-2009
Project Duration: 
36months
Project costs: 
3 590 000.00€
Technological Area: 
Photovoltaics
Market Area: 
Alternative Energy

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.