Coordination-Induced p-Type Selectivity and Enhanced Hole Mobility in an Ambipolar Organic Semiconductor via Electron Passivation

Abstract

A unipolar organic semiconductor with high mobility is crucial for various optoelectronic devices. In this study, a benzo[c]cinnoline-based organic semiconductor (TPA)2Ab with ambipolar transport properties is converted into a unipolar (p-type) semiconductor by reacting with the Lewis acid palladium tetrachloride (PtCl4). This reaction reduces the hole trap-state density of (TPA)2Ab from approximately 1016 cm-3 to a level that cannot detect a measurable trap-filled limit (VTFL) in the resulting [(TPA)2Ab]PtCl4 complex. Consequently, the hole mobility increases significantly from 3.4×10-5 to 3.9×10-3 cm2·V-1s-1, followed by a reduction in electron mobility from 1.4×10-5 to 4.1×10-7 cm2·V-1s-1.