Structural and optoelectronic characterization of organic vapor phase deposited thin films of oriented DH6T molecules

Growth and orientation of the molecules in thermally evaporated thin films of α, ω-Dihexylsexithiophene (DH6T) on oxidized Si (100) substrate have been investigated. XRD studies revealed that grown thin films are crystalline with monoclinic structure. Polarized photoluminescence studies further revealed that the molecules in the grown thin films are oriented vertically at an angle of 32.68° with respect to the substrate normal. AFM images showed a step like circular structure with domain size and step height ∼800-1000 nm and 3-4nm respectively. The observed step height was approximately equal to molecule length of DH6T, which also suggested that the molecules adopt a standing orientation.