In situ structural characterization of picene thin films by X-ray scattering: Vacuum versus O2 atmosphere

► Structural characterization of picene thin films under vacuum and O2 atmosphere by X-ray scattering. ► Determination of unit cell structure, film thickness and roughness. ► Formation of highly oriented and ordered crystalline domains. ► A very small and irreversible change in film morphology by O2 atmosphere. ► Implication of O2 gas sensing mechanism of picene thin film-based organic field-effect transistors.