The effect of bridging groups on the charge transport properties of benzothiophene-substituted anthracenes

Abstract

A series of novel asymmetric anthracene derivatives, namely 5-BTA, 5-BTVA, and 5-BTEA, consisting of a single bond, vinyl, and ethynyl bridged benzothiophene and anthracene core were synthesized. Single crystal structure analysis reveals that all three compounds adopt head–head bilayer stacking along the molecular long axis and herringbone packing along the short axis. The vinyl-bridged 5-BTVA exhibits stronger intra-layer intermolecular interactions, which shows characteristic regular shape with sharp edges and have a suitable thickness (<50 nm) to construct transistors, obtaining a 5–10 fold hole mobility over 10 cm² V⁻¹ s⁻¹ than 5-BTA and 5-BTEA. The better energy level alignment of 5-BTVA to Au electrodes also induces a lower contact resistance. The temperature-dependent device physics studies reveal the low trap density and low activation energy characteristics of 5-BTVA.