Structural evolution of spin coated poly(3-hexylthiophene) thin films probed by X-ray reflectivity

The effects of thermal annealing and solvent vapor annealing on the structures (both along the out-of-plane and in-plane directions)of spin coated poly(3-hexylthiophene) [P3HT] thin films were investigated using X-ray reflectivity (XR) techniques. The film thickness (D), bilayer thickness (d) and crystallite size (ξ) of the films obtained from the XR data analysis were utilized to understand the effect of thermal annealing and solvent vapor annealing on the internal structures as well as on the surface and interfacial morphologies. Thermal annealing wasfound to enhance the edge-on oriented out-of-plane crystallite size and in-plane ordering whereas solvent vapor annealing reduces the out-of-plane crystallite size and deteriorates the in-plane ordering.