The growth and electronic structure of azobenzene-based functional molecules on layered crystals

In situ ultraviolet photoelectron spectroscopy is used to study the growth of ultrathin films of azobenzene-based functional molecules (azobenzene, Disperse Orange 3 and a triazatriangulenium platform with an attached functional azo-group) on the layered metal TiTe2 and on the layered semiconductor HfS2 at liquid nitrogen temperatures. Effects of intermolecular interactions, of the substrate electronic structure, and of the thermal energy of the sublimated molecules on the growth process and on the adsorbate electronic structure are identified and discussed. A weak adsorbate–substrate interaction is particularly observed for the layered semiconducting substrate, holding the promise of efficient molecular photoswitching.