Epitaxial Interfaces in Rubrene Thin Film Heterostructures

Rubrene (RUB) single crystal displaying the orthorhombic polymorph structure is one of the most promising organic semiconducting material in terms of charge carrier mobility and exciton diffusion length. In view of the development of RUB-based devices where structural disorder in the active components would reduce performances, RUB has to be integrated in the form of crystalline thin film either as a single active component or as a part of multilayer heterojunctions. Here, we show how to obtain highly crystalline and oriented RUB thin film heterostructures by growing RUB on top of another organic semiconductor thin film used as templating layer, thus taking advantage of organic epitaxy. A detailed analysis of the heteroepitaxial interface in terms of adhesion energy is presented with a detailed discussion of the epitaxial relationship between RUB overlayer and the layer underneath and of the driving forces leading to organic epitaxy with RUB