**4. Optoelectronically active materials**

Optical and electrical properties of plasma deposited films, sometimes unique indeed, as well as the easy of their deposition, at low temperature and low cost, on inexpensive substrates of almost any size and shape, render these materials very attractive for optoelectronic applications. The possibility to tailor optical parameters, such as refractive index and extinction coefficient, and what is particularly important - the ability to adjust parameters of the electronic structure, such as transport gap, optical gap, density of localized states, etc., recommend these plasma films as active photoelectric elements, e.g. for solar cells and water splitting cells.
