Solar energy can be cheaper

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FACULTY OF CHEMISTRY

One of the most important challenges for today's scientists is obtaining energy from alternative sources and limiting the use of coal or gas in power plants. The research team supervised by Professor Szczepan Zapotoczny decided to address this issue. The aim of the work became to find a cheap, clean and efficient method of generating energy through the improvement of systems used in photovoltaics.

Clean sources in the form of wind or hydroelectric power plants have to be constructed in locations that meet the relevant conditions, as they can also have an adverse effect on the environment. Nuclear energy is associated with numerous problems, one of which is depositing radioactive waste.

Photovoltaics – science dealing with the transformation of sunlight into electric energy.

Commonly available solar energy is still treated only as an important energy alternative, mainly due to its limited efficiency and high costs of transforming it into electric energy. It is worth focusing on creating such materials and systems whose application will enable us to solve the problems that are currently limiting the efficiency of photovoltaic cells, so that in the future they may become a real alternative for conventional energy sources or even replace them.

Electric energy from the Sun

The operation of photoelectric cells is based on the photovoltaic phenomenon, enabling the cells to transform the energy of sunlight into electric energy. It is a commonly used, environmentally friendly method of generating electric energy, as it may be used everywhere the sun is shining. The main disadvantage of modern photovoltaic cells (solar panels), which are produced from silicon, is the low efficiency of electric energy generation in relation to the manufacturing cost of the photovoltaic cells themselves. Many research groups throughout the world are carrying out research on photovoltaic cells created with use of conductive polymers – plastics that conduct electric current like metals. Relatively low production costs, a simple manufacturing process and the ability to create thin, elastic panels make these polymers the hope for popularization of photovoltaics. The disadvantage of such photoelectric cells is still their low maximum efficiency of transforming solar energy into electric energy. It amounts to 8%–10% (this is the percentage of solar energy that is successfully transformed into electric energy; the rest is lost as it is transformed to heat, which is undesirable in this case) and it is lower than in conventional semiconductor (silicon) cells produced commercially (15%–20%).


Photo: © DebbieMous | freeimages.com

Give a direction to the flow of electrons

Charge carriers created in photovoltaic cells under the influence of light have to be transported to the relevant electrodes in order to generate voltage and let the electric current flow. In conventional photovoltaic cells, the generated carriers have either too long a way to go or they move in various directions, ultimately never reaching the electrodes. Such a disadvantageous flow of carriers causes a significant reduction in the efficiency of the transformation of solar energy into electric energy. Within the conducted research, scientists from the Jagiellonian University propose to replace conventional structures of photovoltaic cells (images A and B in the illustration) with a regular arrangement of conductive polymer brushes (image C) that are capable of directing the transport of charge carriers.

Everybody has a toothbrush, hairbrush or clothes brush at home. These are macroscopic objects, whose counterparts can also be found in the nanometric world (one nanometer is one onemillionth of a millimeter). Polymer brushes are materials consisting of a surface to which single polymer chains are attached with one end – like fibers in a toothbrush. "Our material is an innovative solution on a global scale, as for the first time we succeeded in obtaining regularly arranged polymer chains capable of conducting electricity, attached to a gold metal surface. The brushes created in our laboratory are characterized by high conductivity, comparable to that of metals," explained Professor Zapotoczny.

These new polymer brushes will be used for the construction of a photoelectric cell. Due to the minimization of the loss of generated electricity, it should be characterized by high efficiency while maintaining a low cost and an easy manufacturing process.


Research teamy: Szczepan Zapotoczny, PhD – Project Manager, Michał Szuwarzyński, PhD, Karol Wolski, MSc