Regensburg 2019 – wissenschaftliches Programm
CPP 66.2: Vortrag
Freitag, 5. April 2019, 10:15–10:30, H18
Comparative Study of Semiconductivity in Metal-Organic Frameworks — •Christoph Muschielok and Harald Oberhofer — Technische Universität München, Germany
Metal-Organic Frameworks (MOFs) are artificial, self-assembled networks of metal centers connected by organic linker molecules. Often they exhibit large pores, into which small molecules may be absorbed. While many potential applications for semiconductive MOFs in e. g. sensors or electrocatalysis are imaginable, only very few examples of non-insulating MOFs have been found to date. Theoretical studies indeed 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 conductive MOFs. However, the intrinsic carrier density is only one factor governing electrical conductivity, with the other major contribution being the charge carrier’s mobility. This, we study in bulk MOF crystals using a band transport model and thereby establish an upper limit estimate for the mobility. We outline the factors limiting the mobility exemplarily for M(ta)2 MOFs where M stands for different transition metal centers. These share the same crystal structures but vary strongly in their carrier mobilities, hinting at first design criteria for future semiconducting MOFs.