February
Picture of the Month - February 2025
Recovery of Critical Resources from Thin Film Solar Cell Materials via CVT
Thin film solar cells based on cadmium telluride have the shortest lifecycle energy payback time, the lowest water consumption and carbon footprint of all photovoltaics (PV). However, CdTe and its components are toxic and considered critical resources in the periodic table of elements. Therefore, a combined chemical process was developed for both components, in which they can be separated via a gas phase process. By means of chemical vapour transport (CVT), tellurium can be separated with sulphur giving mixed S/Te-rings in the gas phase that separate into the elements after a temperature gradient. Cd is transformed into the oxide with air and can be reduced to the metal with abundant compounds like natural gas and then transported. Separation >99.95% can be achieved without further purification. The process was developed to be carried out in open flow systems that are suitable for a chemical recycling process being sustainable also due to cycling of the transport reagents and limited energy consumption due to moderate process temperatures.
Reference: L. H. Bemfert, J. Burkhart, A. Sedykh, S. Richter, E. Mitura, M. Maxeiner, G. Sextl, K. Müller-Buschbaum, ChemSusChem., 2024, 18, e202400785, DOI: 10.1002/cssc.202400785
This picture was submitted by Prof. Dr. Klaus Müller-Buschbaum.
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