ABSTRACT
In this chapter, the authors discuss the general properties of light absorption and luminescence in solids, nanostructured materials, and molecules. The authors address the general concepts of quantum efficiency and quantum yield that govern the conversion between electricity and light. Finally, the authors review basic recombination mechanisms in semiconductors and the methods of determination of carrier lifetime. Incident radiation on a material results in different types of interactions. The incident light can be reflected at any surface. A part of the radiation is transmitted through the back surface. Randomly textured surfaces or regularly textured surfaces enhance the light absorption providing a light trapping effect due to the randomizing of the internal reflection angle avoiding the escape of internally reflected rays. This effect results in a much longer propagation distance of the light ray and, hence, a substantial increase of absorptance.
