Photovoltage effects in polypyrrole–diamond nanosystem

Thin films of polypyrrole (PPy) are electrochemically polymerized in the thickness 25 nm on hydrogen-terminated intrinsic diamond surface exhibiting two-dimensional surface conductivity of 5 × 10− 5 (S/). Opto-electronic properties of the system are characterized by Kelvin force microscopy detecting surface potentials. Shifts of the surface potentials of diamond and PPy under visible light illumination are attributed to sub- and super-band gap surface photovoltage effects changing energetic band bending in the range of 100–200 meV. We present a model considering influence of diamond surface termination, surface states and highly resistive bulk properties as well as excitonic transport in PPy. The model suggests a charge transfer between PPy and diamond.