1. The different classes of luminescent nanomaterials

A material is said to be photoluminescent when it is capable of emitting light of a different wavelength to that used to excite it (see figure 1 ). There is a huge diversity of luminescent materials, from natural minerals to artificial organic dyes. In the early 1980s, researchers demonstrated that the size of objects could strongly modify the luminescence properties of certain semiconductor materials. Subsequently, a large number of other materials were synthesized in...