Low Cost Solution Processed CIGS Solar Cells

The market for photovoltaic (PV) modules has grown at 35 % p.a. compound over the past 15 years and will exceed 50
GW in 2014. The drivers behind this extraordinary growth include the rising cost of fossil fuels, concerns over security of
energy supplies and worries over climate change. Governments agencies world wide, including the DECC in the UK, are
encouraging the deployment of PV through incentives. However as the cost of PV reduces many important regions are now
at "grid parity" which removes the need for subsidies. At this point the market for PV is expected to rocket. This project will
develop a new solution processed thin film photovoltaic (PV) device from a nanoparticle precursor, which offers a cheaper
route to producing PV modules. The aim of the project will be to integrate technologies developed by the project partners,
to improve the efficiency of small area solar cells, then to scale the technology to mini-module dimensions, while
maintaining a focus on reducing the cost of the process. The application of the technology to flexible substrates will also be
assessed. Lower cost processing of modules will develop a lucrative business for CIGS nanoparticle inks and even
greater growth of solar energy deployment.

Pathways to impact
The market for solar modules has increased by 35% pa compound over the past 15 years. About 90% of solar module
production is currently based on crystalline silicon. However, second generation solar cells based on thin film technology
have an inherent advantage because less material is required for their manufacture, and with increasing efficiency, costs
are reducing rapidly.
High volume manufacturing of thin film PV is recent and the manufacturing processes used are still developing. This
project aims to use a solution based process using CIGS nanoparticles to provide a lower cost route to module production.
Nanoco has already established proof of principle and has achieved an impressive 14% conversion efficiency. The aim of
this project is to push the cell efficiency to >17% and establish process scale up to sub-module dimensions.
The collaborators in this project are the immediate beneficiaries. Nanoco has a strong portfolio of patents to protect its
technology for nanoparticle synthesis and has already established the feasibility of using spray techniques for large area
modules. Nanoco has already engaged with the major manufacturers of thin film CIGS modules and the route to
exploitation is clear once the technical challenges addressed by this proposal are overcome. The project has a range of
wider beneficiaries because lower cost renewable energy has clear environmental benefits including the reduction of
carbon emissions.
CREST is aware of the value of IP and will ensure that protection has been obtained prior to any public disclosure. At that
point, CREST is in an excellent position to disseminate the results of the project. Loughborough University leads the
EPSRC Supergen SuperSolar Hub which now has 8 core members, over 50 Associates and over 400 Network members.
Professor Michael Walls is the Director of the Hub and PI on this project. The Hub has organized 10 events each year
since its inception which provide venues for dissemination and networking in the UK. Walls is also a member of the Solar
Energy Special Interest Group (SESSIG) set up by Innovate UK to encourage industrial development in solar energy. He
is a member of the DECC UK PV strategy group and co-chair of DECC's Task force on PV Innovation. Recently, he
became a Director of the Advisory Group for The Solar Cloth Company Ltd (TSCC) which addresses the market for flexible
modules (CIGS) over car parks and commercial buildings. CREST is also working with M-solv Ltd to develop a 'One Step
Interconnect' (OSI) process using laser ablation and inkjet printing. This process is ideal for CIGS modules and Nanoco
will sub-contract the interconnect to M-solv within this project. A powerful UK supply chain is developing in thin film PV and
this project is crucial to its development.
Members of the CREST team attend the IEEE Specialist Photovoltaics Conference (PVSC) in the United States. This is
arguably the most important PV forum since it attracts the most prominent researchers from both research Institutions and
Industrial R&D organisations. It is the perfect venue for dissemination and often leads to the development of commercial
opportunities. Walls is a member of the International Advisory Board for the IEEE PVSC.
CREST has established important relationships with the National Renewable Energy Laboratory NREL in the United States
. NREL have connections with PV module manufacturers worldwide. The link with NREL will be useful to Nanoco both
technically and commercially. The commercial exploitation of the project outcomes will be the responsibility of Nanoco
Technologies Ltd. Nanoco will use a licensing business model targeting chemical companies for their nanoparticle
synthesis technology and CIGS module manufacturers for the supply of materials. CREST will assist this activity through its
worldwide network of contacts in the solar module industry.