Thickness dependence of organic magnetoconductance of polymeric semiconductor device based on an ambipolar polymer AnE-PVstat

We explore the magnetoconductance (MC) of polymer thin-film device, based on an anthracene containing poly (p-phenylene-ethynylene)-alt-poly (p-phenylene-venylene) (PPE-PPV) denoted AnE-PVstat, for different thicknesses to clarify the role of electron hole (e-h) pairs on the MC effect. Here, by changing the thickness of the active layer, we observed a positive MC which reaches up 1.5% at a magnetic field of 425 mT at room temperature. We found that the increase of the thickness is accompanied by the decrease of the MC effect. To analyze the experimental data, we used the electron hole (e-h) pair model based on the Stochastic Liouville Equation with spin mixing by hyperfine fields and different singlet and triplet recombination and dissociation rates k(s), k(T), q(s) and q(T). The theoretical calculations are well consistent with the experimental results.