Organic solar cells manufactured using light, the idea of Luca Beverina, researcher of organic chemistry in the Materials Science department of the University of Milan-Bicocca, improves the production process of organic photovoltaic cells by offering the user more efficiency in converting solar energy into electricity and a reduction in production costs. Thus, in 2012, the fourth place in the Cariplo "Ricerca di Frontiera" Prize, 130 thousand euros, went to ExPhon (Exploitation of Self-Assembly and Photochemistry for the straightforward, low cost production of Nanostructured Organic Photovoltaic Devices), the project of this team who thought of using light both as a fundamental reagent in the preparation of the photovoltaic device and as a power supply to the cell itself once assembled. With excellent results.
1) What does the ExPhon project consist of? What is it based on?
The project stems from the need to make new photovoltaic technologies with a completely organic basis, compatible with large-area and low-cost manufacturing processes. In this field, in fact, the most advanced international research has recently shown that light / electricity conversion efficiencies of the order of 9% are realistically possible. However, at the present time the cell prototypes often have areas less than 1 cm2 and the increase in the cell area involves drastic drops in efficiency. The ExPhon project proposes an operationally simple strategy to obtain a better degree of control over the performance of these devices even in the case of high active areas.
2) What new features does ExPhon introduce?
To obtain efficient organic photovoltaic cells, it is necessary to control the spatial arrangement of the components of the active layer of the device on a nanometric scale. This is where the project intervenes by forcing the components of the device to arrange themselves spatially in the correct way, exploiting the action of light. The active layer of an organic cell is made up of two distinct materials that must be in contact with each other but not completely mixed. The problem is that both materials are soluble in the same solvents so it is not possible to deposit them in sequence. The simplest analogy concerns watercolor painting: if you try to lay a color very close to a previous stroke, the two colors blend immediately. The Exphon project aims to create active materials that once exposed to light become totally insoluble, thus making it possible to sequentially deposit the two components under controlled conditions.
3) What are the advantages of ExPhon in industrial terms?
Advantages would be obtained in terms of increasing the efficiency of converting solar energy into electrical energy of organic cells, now around 10 percent. There would also be a reduction in production costs. They would be obtained, I say, because if the theory is confirmed, and today it is reasonable to think so, high-area photovoltaic cells will be obtained by simple sequential deposition of two paints, interspersed with an exposure to a lamp completely similar to those used industrially for the processes of photolithography. And that's what those benefits would bring to the industry.
4) How did the idea come about? How long have you been working on it and in how many?
The idea was born as part of a multi-year research carried out in partnership with a US company and dealing with organic photovoltaic technologies. The idea of combining organic photovoltaics and photolithography techniques is original and as far as we know, we are currently the only ones working on it. We have already achieved encouraging results but there is still a long way to go.
Luca Beverina awarded for the ExPhon project which won 4th place in the Cariplo “Ricerca di Frontiera” Prize.
5) How much does this project cost?
A feasibility study is compatible with the funding received. If the results prove to be up to expectations, the additional minimum investment to translate the principle into a technology should reasonably be measured in a few million euros. We are confident that if the idea turns out to be successful, finding adequate funding would be possible.
6) ExPhon was born within the Mib-Solar Center, what is it about?
The MIB-SOLAR Center was established at the Materials Science Department of the University of Milan-Bicocca in order to promote and encourage the study and research of new materials and devices related to the exploitation of solar energy in its various forms. For example, as a renewable energy source in photovoltaic processes or as a renewable energy source in processes other than the photovoltaic effect and photocatalysis.
7) What should we expect from photovoltaic research?
However, it is undoubted that the networks for electricity intended for domestic consumption will be increasingly interested in photovoltaics, even if it cannot be the only answer to the energy needs of the industrialized world.
It is difficult to predict today what the future holds but in just one hour the sun deposits on the earth's surface an amount of energy equal to the total annual requirement of humanity, but it is extremely widespread energy, therefore difficult to exploit, however I am convinced that its use will become a fundamental pillar of a more sustainable future.
Currently, the development of photovoltaic technologies is supported by government incentives without which it would not be economically viable, however, and that is why all the alternative technologies currently being studied work on the dual direction of reducing costs and increasing efficiencies.
Interview byMarta Abbà