Investigation of polystyrene-b-polyferrocenyl silane diblock copolymer thin films via conducting probe atomic force microscopy

Conducting probe atomic force microscopy (CP-AFM) was used to investigate the electronic properties of polystyrene-b-polyferrocenyl silane (PS-b-PFS) diblock copolymer thin films. In this system, cylindrical domains of polyferrocenyl silane, a weak semiconductor, is surrounded by polystyrene, an insulating material. Mapping the electrical current response of the film to an applied voltage bias showed a correlation with the location of PS and PFS domains as evidenced by concurrent topographical and lateral friction imaging. The higher conductivity in the PFS region is believed to arise from localized oxidation rather than through-chain electron tunneling. Polyferrocenyl silane was additionally observed to exhibit diode-like behavior. Experiments were performed using contact mode AFM operation under ambient conditions and also in low-oxygen environments. The electronic properties of PFS in addition to the locally ordered configuration afforded by the self-assembly process provide a system which may have possible device applications.