Electron and hole transport in poly(fluorene-benzothiadiazole)

We investigate the electron and hole transport in poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT). An Ohmic hole contact on F8BT is achieved by using the high work function anode MoO3 as hole injection contact, enabling the occurrence of space-charge limited currents. The electron transport in F8BT is trap-limited and the traps can be deactivated using n-type doping by decamethylcobaltocene (DMC). Due to the alignment of the energy levels of DMC and F8BT the electrons from the DMC donor not only fill the traps but also fill up the lowest unoccupied molecular orbital of F8BT such that the electron transport can be enhanced beyond the hole transport. (C) 2011 American Institute of Physics. [doi:10.1063/1.3574907]