Metal-organic frameworks (MOFs) are artificial, self-assembled networks built from metal centers which are interconnected by organic linker molecules. Many representants of this class of compounds exhibit large pores into which small molecules may be absorbed. While many potential applications for semiconducting MOFs in e. g. sensors or electrocatalysis applications are imaginable, only few examples of non-insulating MOFs have been found to date. Indeed, theoretical studies suggest that pure MOF bulk crystals have insufficient intrinsic charge carrier density to show finite conductivity. It is generally suggested that this drawback is overcome by defects in the crystal structure for the few known conducting MOFs. However, next to the intrinsic carrier density, the electrical conductivity is governed by the charge carrier mobility, which we study in bulk MOF crystals using a band transport model. By that we establish an upper limit estimate for the mobility of the charge carriers. We validate our theoretical methods using experimental trends and outline the influence of the mobility-limiting factors for transition metal triazolate crystals, M(ta)<sub>2</sub>, with M denoting the metal center. These share the same crystal structure but vary strongly in their carrier mobilities, thereby opening a gateway for computational materials design of future semiconducting MOFs.

Towards computational materials design of metal-organic framework semiconductors

2019 Fall National Meeting

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