UCL researchers develop low cost solar cells

Photo: UCL website.

A team co-led by UCL researchers has substantially increased the efficiency of a new type of solar cell, potentially paving the way for its use as a low cost, environmentally friendly alternative to existing solar power technology.

 high-performance, low-cost devices and support a green economy.”

“These particular solar cells have made huge leaps in efficiency in less than a decade, from 1-2% to 9%. This gives us confidence that further improvements are possible, and the goal is to further improve efficiency so it is comparable with silicon-based solar cells.”

The calculations were based on quantum mechanical models and required massive computing power – some calculations were performed on more than 10,000 CPUs (central processing units) in a network running simultaneously for 24 hours.

The work was achieved using the UCL Kathleen High Performance Computing Facility (Kathleen@UCL), the Imperial College Research Computing Service, the ARCHER2 UK National Supercomputing Service and the UK Materials and Molecular Modelling (MMM) Hub.

As well as consisting of non-toxic, earth-abundant elements and being cheap to produce, the bismuth-based nanocrystals have proven to be very stable, the researchers say, avoiding degradation of the cell over long periods of time.

The research team note that the solar cell material was 10-50 times thinner than current thin film photovoltaic (PV) technologies and 1,000 times thinner that silicon PV.

Co-author Professor Gerasimos Konstantatos of ICFO said: “The devices reported in this study set a record among low-temperature and solution processed, environmentally friendly inorganic solar cells in terms of stability, form factor and performance. We are thrilled with the results and will continue to proceed in this line of study to exploit the intriguing properties [of the precisely engineered nanocrystals] in photovoltaics as well as other optoelectronic devices.”

Seán Kavanagh is a third-year PhD candidate supervised by Professors David Scanlon (UCL Chemistry) and Aron Walsh (Imperial College London), both co-authors on the paper. Professor Scanlon said: "Atomic disorder (atomic site swapping) on the metal sites in solar cell absorber materials is normally associated with loss in device performance. In this study we demonstrate that certain types of disorder are actually beneficial for performance, allowing us to realise a world record efficiency, and potentially opening up new directions for solar cell research. This work highlights once again the power of combining predictive density functional theory calculations and experiments to gain insight into materials properties."

Their groups’ research focuses on understanding the underlying chemistry and physics which govern the properties of materials, and then leveraging these insights to design high-performance devices that can be produced experimentally.

In particular, the groups study emerging energy materials, such as solar cells, batteries and thermoelectric generators, with the aim of discovering low-cost high-efficiency devices to support a green economy.

The study received support from the EPSRC, the European Research Council, and the European Union’s Horizon 2020 research and innovation programme, among other bodies.

Dr Kedar Pandya, Director for Cross-Council Programmes at EPSRC (Engineering and Physical Sciences Research Council), part of UK Research and Innovation, said: “As we move towards environmentally-friendly, low carbon sources of energy the team’s findings are an important step towards increasing the efficiency of solar power technology.

“And by potentially reducing our dependency on the toxic or rare elements currently needed to produce solar cells, these findings could also deliver further environmental and cost benefits.

“It also demonstrates how the UK’s new supercomputer, ARCHER2, is helping researchers to produce results that could deliver benefits for all of society and the environment.”

This article was first published on 15 February by UCL.