High intra-chain hole mobility on molecular wires of ladder type poly(p-phenylenes)

The high frequency mobility of charge carriers on isolated ladder-type polymer chains with lengths ranging from 13 to 54 monomer units was measured. Experiments were performed on isolated chains in dilute solution and on bulk solid samples. The ac mobility of charge carriers measured at a microwave frequency near 30 GHz is strongly dependent on the chain length. The intra-chain motion of charge carriers can be described by one-dimensional diffusion between infinitely high reflecting barriers, representing the chain ends. Theoretical analysis of the experimental data yields an intra-chain mobility of charges on isolated ladder-type polymers in dilute solution near 600 cm2/Vs. For bulk solid samples the intra-chain mobility has a lower value of 30 cm2/Vs, which is attributed to energetic disorder in the bulk due to interactions between different polymer chains. With the high intra-chain mobility the ladder-type polymer is a promising candidate for future use as an interconnecting wire in molecular-sized electronics.Opto-Electronic Materials SectionApplied Science