Resonant Photoconductance of Molecular Junctions Formed in Gold Nanoparticle Arrays

We investigate the photoconductance properties of oligo(phenylene vinylene) (OPV) molecules in metal?molecule?metal junctions. The molecules are electrically contacted in a two-dimensional array of gold nanoparticles. The nanoparticles in such an array are separated by only few nanometers. This allows to bridge the distance between the nanoparticles with molecules considered as molecular wires such as OPV. We report on the photoconductance of electrically contacted OPV upon resonant optical excitation of the molecules. This resonant photoconductance is sublinear in laser intensity, which suggests that trap state dynamics of the optically excited charge carriers dominate the optoelectronic response.