Probing hopping conduction in conjugated molecular wires connected to metal electrodes

Understanding electrical transport processes in molecules connected between metal electrodes is a central focus in the field of molecular electronics and is important for both potential applications and fundamental research purposes. This short review summarizes recent progress in assembling and measuring strategies for long conjugated molecular wires within molecular junctions, and introduces several new in situ methods to prepare molecular wires connected to electrodes. Following a brief introduction to charge transport mechanisms, particular examples of molecular wires in the recent literature are presented to discuss the influence of molecular length, temperature, and applied voltage on the transport properties with emphasis on the tunneling-to-hopping transition. The review concludes with an outlook on future hopping transport experiments in long conjugated molecular wires.