Distinct Hole and Electron Transport Anisotropy in Ambipolar Nickel Dithiolene‐Based Semiconductor

Abstract

Abstract Understanding anisotropic charge transport in molecular semiconductors is crucial for device optimization, yet its intricate dependence on orbital‐specific intermolecular interactions and molecular packing remains a challenge, especially in ambipolar systems. In ambipolar semiconductors, where both holes and electrons participate in conduction, distinct molecular orbitals prompt a critical inquiry: can orbital variations result in coexisting yet distinct anisotropic transport properties within a single component? We confirm this possibility by demonstrating that the air‐stable nickel dithiolene, Ni(4OPr) , exhibits such behavior. Despite its herringbone stacking implying a two‐dimensional electronic structure, Ni(4OPr) uniquely exhibits distinct intermolecular interactions for hole (HOMO‐to‐HOMO; HOMO = highest occupied molecular orbital) and electron (LUMO‐to‐LUMO; LUMO = lowest unoccupied molecular orbital) transport. Crucially, this leads to highly anisotropic hole transport pathways, while electron pathways are remarkably isotropic, demonstrating a stark contrast in their transport anisotropies. Leveraging the high crystallinity, grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) determined in‐plane molecular orientation. This enabled experimental verification of distinct anisotropic hole and electron transport, directly governed by orbital‐specific intermolecular interactions, in an ambipolar molecular semiconductor. Our findings, demonstrating coexisting yet distinct anisotropic transport properties for both carriers within a single component, significantly advance the understanding of ambipolar molecular semiconductors and broaden their scope for future device applications.