EN
The general properties of the layered transition metal dichalcogenides and the possibility to modify these materials by intercalation are reviewed. Examples are given of experimental results obtained by using angle-resolved photoelectron spectroscopy and very-low-energy electron diffraction. The possibility to use layered semiconductors as model systems in studies of e.g. Schottky barriers and surface photovoltage is exemplified by the Rb/WSe_2 system. Attention is also paid to the use of van der Waals epitaxy in interface studies, and its possible practical applications. The potential of layered semiconductors like WSe_2 in solar cell applications is also mentioned.