Rapid Evaluation of Electron Mobilities at Semiconductor-Insulator Interfaces in an Ambient Atmosphere by a Contactless Microwave-Based Technique.

Abstract

Intrinsic mobility of electrons at the interfaces between crystalline organic semiconductors and insulating dielectric polymer films was rapidly evaluated in an ambient atmosphere by TRMC@Interfaces, a noncontact and nondestructive method based on dielectric loss spectroscopy of microwaves. By just preparing simple metal–insulator–semiconductor devices, local-scale motions of charge carriers injected into the interface by pulses of gate bias voltage were monitored through reflected microwave changes, resulting in the evaluation of local-scale charge carrier mobilities together with the value of trap density at the interface. The evaluated high electron mobilities of 12 cm2 V–1 s–1 for N,N′-bis(cyclohexyl)naphthalene-1,4,5,8-bis(dicarboximide) (DCy-NDI) and 15 cm2 V–1 s–1 for N,N′-dioctylperylene-1,4,5,8-bis(dicarboximide) (DC8-PDI) are the benchmarks for organic semiconducting materials that are comparable with the highest ones reported from the field-effect transistor devices. The present TRMC@Interfaces was found to serve as a rapid screening technique to examine the intrinsic performance of organic semiconducting materials as well as a useful tool enabling the precise discussion on the relationship among their local-scale charge carrier mobility, thin-film morphology, and packing structure.