A conductive liquid crystal via facile doping of an n-type benzodifurandione derivative

Two n-type molecular organic semiconductors (TI-BDF1 and TI-BDF2) consisting of thiophene-substituted indolin-2-one (TI) and benzodifurandione (BDF) with different branched side-chains have been synthesized to study the effect of molecular structure on molecular order, liquid crystal (LC) properties, and charge-transport. By tuning the branching point of the side-chains, TI-BDF2 shows a preferable edge-on p-face orientation and a high degree of liquid crystallinity, resulting in 4 orders of magnitude higher electron mobility than that of TI-BDF1. Subsequent n-doping of TI-BDF2 thin film with a thermally stable phosphonium salt affords a high electrical conductivity of 0.4 S cm(-1).