Ambipolarity and Dimensionality of Charge Transport in Crystalline Group 14 Phthalocyanines: A Computational Study

The charge transport properties of ten group 14 phthalocyanine crystals are investigated by means of kinetic Monte Carlo simulations based on experimental X-ray structures. All investigated materials are predicted to exhibit an ambipolar semiconducting behavior, with hole and electron mobilities lying in the range 0.1–1 cm2 V–1 s–1, showing their potential for organic electronic devices. The simulations also provide evidence that the dimensionality of charge transport in these materials can be finely tuned by substituting the phenoxy axial groups with fluorine atoms and by varying their number and positions; a complete substitution gives rise to two-dimensional transport for both electrons and holes. Most remarkably, one of the investigated compounds that incorporates iodine-phenoxy groups as axial substituents exhibits the largest mobilities for both electrons and holes, owing to large intermolecular couplings and low reorganization energies, and thus emerges as a highly promising one-dimensional semiconductor.