Space-charge-limited hole current in poly(9,9-dioctylfluorene) diodes

摘要

Characterization of the hole transport in blue-emitting polymers as polyu00019,9-dioctylfluoreneu0002 u0001PFOu0002nis strongly hindered by their large ionization potential of u00036 eV. Using common anodes asnpolyu00013,4-ethylenedioxythiopheneu0002/polyu0001styrenesulphonic acidu0002 leads to a strongly injection limitedncurrent. We demonstrate that molybdenum trioxide forms an Ohmic hole contact on PFO, enablingnthe observation of a space-charge-limited currentu0001SCLCu0002. This allows a direct determination of thenhole mobility PFO of 1.3u000110−9 m2 /V s at room temperature, in good agreement with previouslynreported mobility values determined by time-of-flight measurements.