Carrier mobility of organic thin films using lateral electrode structure with optical slits

The authors have studied the carrier mobilities of organic thin films using a time-of-flight (TOF) technique with lateral electrode structures and optical slits. For a triphenylamine derivative (TPD), which is a typical hole transport material, the obtained mobility was similar to the results of the conventional TOF measurement using a sandwiched structure with a thick film. Moreover, they have succeeded in evaluating the carrier mobility of an iridium complex [Ir(ppy)3], which is a phosphorescent material, and hole mobility on the order of 10−3cm2∕Vs was obtained. This technique, which has the merits of free alignment of excitation light and no need for the preparation of a thick sample, is effective for the evaluation of carrier mobilities in thin organic materials.