Effect of the fibrillar microstructure on the efficiency of high molecular weight diketopyrrolopyrrole-based polymer solar cells.

The nature of the solubilizing alkyl side chains has a strong effect on the performance of semiconducting diketopyrrolopyrrole polymers in organic solar cells with fullerene acceptors. The effect relates to the width of semicrystalline polymer fibrils that form in these blends. If the width of the fibril is wider than the exciton diffusion length, fewer charges form and the efficiency drops.

Two-dimensional charge transport in disordered organic semiconductors.

We analyze the effect of carrier confinement on the charge-transport properties of organic field-effect transistors. Confinement is achieved experimentally by the use of semiconductors of which the active layer is only one molecule thick. The two-dimensional confinement of charge carriers provides access to a previously unexplored charge-transport regime and is reflected by a reduced temperature dependence of the transfer curves of organic monolayer transistors.