Structures, Materials, and Scale
The key material in a solar cell is the absorber. These materials are capable of absorption-caused excited states produced by photons with energies in the photon-rich range of the solar spectrum (Fig. 1.1). The resulting excited states must be mobile; i.e., free electron-hole pairs, which can be separated, or excitons, which can be disassociated into free electrons and free holes and separated. Absorber materials can be organic or inorganic semiconductors, dye molecules, or quantum dots, which are the man-made inorganic particle equivalent of dye molecules. In some configurations, the absorption and separation are both accomplished in the same material. In these cases there is ...