This chapter provides an overview on the concepts, materials and devices that involve nanoscience for photovoltaics. First, the general basics of photovoltaics in terms of principle and technologies will be presented. Then, the features specifically associated with the use of nanomaterials in current and future photovoltaic devices will be developed. The optical effects (quantum confinement, photonics, plasmonics), electrical effects (work function) and geometrical effects (interpenetrating structures)which are intrinsic to nanomaterials-will be described at theoretical and experimental levels. Properties of solar cells devices involving nanomaterials such as dye and organic cells, ultrathin cells implementing metal nanostructures, new concept based cells (up and down conversion, intermediate band cells, multiexciton generation, hot carriers …) will be presented.