High Electron Mobility in Ladder Polymer Field-Effect Transistors

Field-effect mobility of electrons as high as 0.1 cm2/(V s) is observed in n-channel thin film transistors fabricated from a solution spin-coated conjugated ladder polymer, poly(benzobisimidazobenzophenanthroline) (BBL), under ambient air conditions. This is the highest electron mobility observed to date in a conjugated polymer semiconductor. Comparative studies of n-channel thin film transistors made from a structurally similar nonladder conjugated polymer BBB gave an electron mobility of 10-6 cm2/(V s). These results demonstrate that electron transport can be as facile as hole transport in conjugated polymer semiconductors and that ladder architecture of a conjugated polymer can substantially enhance charge carrier mobility.