Electroactive MOF Networks

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Here, we aim to develop metalorganic frameworks with periodic, interpenetrating networks of electron donor- and acceptor-phases that give maximum control over the nature of the molecular building blocks with specific electronic properties, their sequence of assembly, their spatial orientation relative to each other, their wall-thickness, and their overall orientation relative to a substrate. We build such highly defined model systems based on MOF structures, to enhance our understanding of the relationship between the electronic and structural parameters and the resulting optoelectronic properties, including charge-carrier dynamics. In one line of research, we wish to synthesize MOFs with different stacked (hetero)aromatic electron donor- and acceptor moieties, thus forming highly ordered (interpenetrating) networks for light-induced charge separation and photodetection. A second line of research is based on the structural paradigm of the MOF-74 topology, in which linear building blocks are connected into honeycomb-like structures through coordination of divalent metal ions. Here, we will vary both the structural and electronic properties of the metal coordination sphere and of the linear building blocks. Moreover, we introduce a strategy to partition the electronically coupled pore systems through Kagome-like tiling in order to protect charge carriers from recombination and to increase their lifetimes. Complementary charge-carrier phases will be introduced into the MOF host structures through inclusion chemistry. Building blocks include extended heterocyclic chromophores with push-pull elements to tune optoelectronic properties, and twisted systems with potential singlet/triplet conversion control for MOF-based light-emitting diodes. Furthermore, we aim to develop film-growth techniques based on different deposition strategies for oriented MOF- and heteroepitaxial MOF-MOF structures, ultimately to be integrated into model photovoltaic devices, photodetectors and MOF-LEDs, and to study their detailed charge-carrier dynamics with a wide range of techniques and in collaboration with other research groups. The work will be complemented with powerful theoretical modeling, addressing optimized structure and packing of the molecular building blocks, advanced electronic property calculations of the MOFs, charge transport calculations and conductance-path searches to determine limiting factors and optimization strategies, as well as morphology prediction for the growth of thin films.