Preface – Focus on Sustainable Electronics

Today's society uses up to 35 tons of material per capita and year for basic needs, luxury or consumer goods, hightech products, etc. Much of it is used in form of functional materials employed in highly specialized devices such as mobile phones. Cumulated sales up to 2008 correspond to 7.2 billions of mobile phones. A new generation of mobile phones comes up every half a year. More than 30 different metals are employed in this device and are essential for its functioning. The fraction of some of these metals in a mobile phone is higher than the typical content in corresponding mineral ores. The life cycle analysis of such a device technology ranging from the acquisition and supply of materials via purification, manufacturing and fabrication, via commercial uses to end‐of‐life disposition and recycling needs to be carried out carefully to ensure a commercial success of the product. Such an analysis comprises a number of quantitative criteria (e.g. reserves and resources of the materials employed, energy consumption of the production process, recyclability), but also qualitative criteria (e.g. social and socio‐cultural aspects, ecological risks, political issues). Thus a life cycle analysis must go beyond a mere techno‐economic analysis to yield resource‐efficient, socio‐economically liable and ecologically benign technologies. The first two articles of this series of six articles on “sustainable electronics” discuss how life cycle analysis needs to be conducted properly. Reller focuses on the case of strategic metals whereas Theis et al. discuss the case of nanostructures. It will become clear to the reader that the principal approach is very similar, but distinct differences occur due to specific properties of different classes of materials. The articles on photovoltaics and thermoelectrics focus on a scenario where the corresponding device modules become mass products. Simple estimates based on element reserves in case of thermoelectric devices easily reveal that materials scarcity will impose major restrictions on the deployment of the established key materials (e.g. PbTe, Bi₂Te₃ as well as Si_xGe_1–x) in mass‐produced modules. Thus, depending on the type of application, a compromise between best efficiency and materials availability needs to be made. The situation in photovoltaics is somewhat different. The analysis makes it clear that all types of mass‐produced solar modules, in particular novel thin‐film technologies, need to compete with the Si‐technology in the end. Nevertheless, there are promising alternatives for absorption materials on the horizon. The last two articles by Fortunato and Martins and by Martins et al. discuss the advances and advantages of oxide semiconductors as abundantly available materials in the context of transparent electronics and electronics on paper, respectively. Conventional Si‐based CMOS electronics cannot compete with oxide electronics in these two areas of application. The example of oxide semiconductors shows the potential of developing sustainable and ecologically benign technologies for specific applications which are compatible with or even better than conventional technologies. The idea for this series of articles was developed during the discussions at the WE‐Heraeus Summerschool “Sustainable Electronics” organized by us at the Physik‐Zentrum in Bad Honnef in August 2010. The issue of sustainable resources management is of major importance for maintaining the wealth of human society. Therefore, it should concern all of us working in materials science in academia or industry. Only few people are specialists in this novel and very interdisciplinary field of research. The six articles cover different facets of the problem. Hopefully, together they will give valuable insight into modern materials resource management and shed some light on its complexity. We would like to thank Stefan Hildebrandt for his help and support in assembling this series of articles as expert opinions. We chose the pss‐format “Expert Opinion” as best suited for our purposes as it allows us to express somewhat personal views on this novel research field of “Sustainable Electronics”, to reach a broader audience and, thus, to hopefully generate useful and intense discussions on the subject (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)