Working towards a sunny future
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity. Solar cells based on bulk silicon are currently the market leader in PV, but thinner cells based on non-toxic, air-stable silicon could displace them. This prognosis is fostered by the strong cost-reduction potential of these cells due to highly effective use of materials at low-energy consumption. However, thin-film silicon suffers from inherently small grains, which limits efficiency to around 10 %. A radical innovation is needed to circumvent this problem. The EU-funded 'All-inorganic nano-rod based thin-film solar cells on glass' (ROD-SOL) project is turning to nanotechnology in a bid to dramatically ramp up efficiency. This will be done by developing and optimising the synthesis of silicon nano-rods on cheaper substrates such as glass or metal foils. These nano-rods are effectively tiny silicon columns whose diameter is measured in nanometres (one nanometre being a billionth of a metre). These minute structures are ideal for trapping light energy so that it can be transformed into electricity. The ROD-SOL project team is currently determining the optimal diameter of the nano-rods, as the diameter influences their efficiency. The nano-rod diameter and dopant (added element to alter electrical properties) concentration for optimum solar cell efficiencies have been derived based on simulations and experiments. The most promising synthesis method for high efficiencies and best large area manufacturability has also been identified. Analysis has been carried out of the thin-film PV technologies as has benchmarking of the ROD-SOL concept with respect to other thin-film technologies. Validation of the nano-rod–based solar-cell material has also been completed. The project team has now produced the first thin-film devices. Further research is needed to up-scale the processes and improve the properties of the materials to approach the efficiency of the most successful alternatives currently available. Once these novel materials and processes have been developed, they will be tested by companies involved in the ROD-SOL project. Assessments and analyses will then be carried out with a view to mass production with great efficiency.
