Competition between Polaron Binding and Disordered Localization on Electronic Transport of Smectic E phase

Abstract

We have investigated effects of polaron-binding energy and energetic disorder of localized states on charge transport in 2-(4-propylthiobutyl)-7-phenylbenzothienobenzothiophene (Ph-BTBT-4S-3) exhibiting Smectic E phase of liquid crystal. The critical temperature Tc = 293K to determine disorder-controlled or polaron-controlled transport was experimentally obtained. Activation energy Ea = 66.6meV due to polaron binding is also obtained in high temperature range T > 293K. We demonstrate how the static disorder disturbs polaronic transport and propose the concept how we can characterize the Gaussian disorder model with small polaron regime in soft crystal.