Thin films and nanostructured coatings are of great and increasing importance for clean tech, including applications to solar energy and energy efficiency. This tutorial review discusses why this is so and surveys the major preparation technologies and their characteristics. Particular attention is given to techniques requiring vacuum or plasmas-with foci on evaporation and sputtering-but a wide range of other techniques is surveyed as well. Large-scale deposition is discussed in some detail, and perspectives are given on possible future developments. (C) 2011 Elsevier B.V. All rights reserved.