The course gives a comprehensive introduction into the principles and materials concepts of solar cells. The four materials concepts are based on large homogeneous crystals (c-Si), sophisticated epitaxial layer systems (III-V semiconductors), semiconducting layers on foreign substrates (thin-film solar cells, a-Si:H, CdTe, chalcopyrites, kesterites) and nanocomposites (quantum dot layers, dye-sensitized solar cells, organic solar cells, photonic structures in solar cells). Lectures will be about basics of solar cells, recombination processes, passivation of defects, charge-selective and ohmic contacts, efficiency limitations and their relation to the properties of the different materials and combinations of materials. Special attention will be paid to a promising newcomer in the field, the class of hybrid organic-inorganic metal halide perovskites.