A group of scientists from Germany and Spain have just published an article that studies the optimization of the manufacturing conditions of semi-transparent solar cells of Cu₂ ZnGeSe₄ to improve its efficiency.

These new solar cells, being semitransparent, can receive light on both sides, be integrated into the windows of buildings or also serve to form a tandem solar panel in which this layer is mounted on top of another type of opaque solar panel that collects light. let the first go through.

Semi-transparent solar cells are the next step in integrating photovoltaic energy into our daily lives. In recent years, kesterite-type material (a mineral from the sulfide mineral class) has attracted special attention for use as an absorbent in these cells due to its low toxicity and its constituents being abundant in the earth.

In this work, the researchers have created thin films of Cu₂ZnGeSe₄ by co-evaporation and subsequent heat treatment at different temperatures (up to 525 ° C). The objective is to investigate the influence of the heat treatment temperature on its properties to determine the optimal manufacturing conditions. The research has been led from the Department of Applied Physics of the Autonomous University of Madrid by Professor Raquel Caballero. The Institute of Optics has collaborated in the characterization of the properties was carried out in the service of optical characterization of materials (SCOM) thanks to the contract AEI / MICINN (PTA2019-016763-I) of technical support personnel with whom the service is offered to other research centers. With the data from this characterization, the role played by the roughness of the film, and therefore the possible scattering of light on its surface, in its transparency was verified.

The development of these new photovoltaic materials allows the so-called BIPV photovoltaic, which consists of manufacturing buildings that use these materials as structures in such a way that the cost of the panels is offset by the reduction in spending on conventional construction materials and also the savings in assembly other photovoltaic panels.

Link to scientific article

The work is a collaboration between the Institute of Optics, the Department of Applied Physics of the Autonomous University of Madrid, the Institute for Energy Research of Catalonia, the Helmholtz Zentrum Berlin für Materialien und Energie, and the Departament d'Enginyeria Electrònica, of the Universitat Politècnica de Catalunya