Luminescent materials for lighting and photovoltaic devices

As far as phosphor applications are concerned, new display and lighting technologies such as electroluminescent displays, plasma and microdot screens, mercury-free fluorescent lamps and light-emitting diodes (LEDs) have, since the 1990s, been the driving force behind research into new, more efficient materials than those previously available on the market. Classic applications using luminophores can be divided into four categories:

• light sources such as fluorescent lamps or LEDs;

• display screens ;

• X-ray detectors ;

• all marking applications such as phosphorescent paints, stamp and banknote marking, etc.

In recent years, research has also focused on integrating luminophores into solar cells to increase light-to-current conversion efficiency.

The aim of this article is not to draw up an exhaustive list of luminescent materials and their characteristics (that would be tedious), but rather to explain the physical processes involved in the phenomenon of luminescence, how they are studied and what new properties we are seeking to exacerbate, given the new applications being developed. We will confine our remarks to inorganic materials, although there are organic fluorescent materials (fluorophores) mainly used in biochemistry and the medical field. Nor will we discuss quantum dots (semiconductor nanocrystals), whose light emissions have applications in a wide variety of fields (lighting, photovoltaics, biology). They have been the subject of numerous studies over the last ten years, and would require an article of their own. The aim of this article is to show how to select materials, luminescent ions and their behavior according to the exciter source used for a given application.