Trapping centers engineering by including of nanoparticles into organic semiconductors

摘要

This paper reports the characteristics of an organic field-effect transistor (OFET) with silicon nanoparticles (NPs) on a semiconductor-gate insulator interface, which work as trapping centers of charge carriers. Charge transport and injection phenomenon were studied by electrical measurements and optical time-resolved microscopy second harmonic generation (TRM-SHG) technique sensitive to injected carrier distribution and internal electric fields. We found that OFETs with low concentration of intrinsic carriers and operating in terms of injection type OFET are extremely sensitive to the internal electric field. An enormous threshold voltage shift due to trapped charge was observed, and the possibility to adjust it by controlling the NP density was found. We demonstrate that the NP film can serve to design the accumulated charge in OFET and thus change in charge injection time and transport properties. The detailed analysis of pentacene OFET based on dielectric properties and the Max well-Wagner model reveals internal electric field created by NPs. Additionally, the effect of NPs is discussed with respect to mobility estimated by electrical and TRM-SHG experiment; its decrease is related to deceleration of carrier propagation by trapping effect.