B05 • Towards All-Boron Electronics

Bridging electron donors and/or acceptors by p-bridges is the leading design for molecular materials used in optoelectronic devices, e.g. organic photovoltaic cells (OPVs), organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), or two-photon absorption (TPA)-induced fluorescence markers. Typically, organic or organometallic building blocks are used in the above-mentioned molecular materials. The incorporation of boron will combine the advantages of the element’s easy and cheap availability and its ability to act as electron donating and electron accepting unit, depending on its specific incorporation into an organic framework. In particular, boron clusters have a high potential for the development of acceptors, donors, and (­­π-)bridges.
The electronic properties of these 3D functional building blocks can be tuned by the cluster type and size, cage heteroatoms, charge, substituents, and the substitution pattern. This allows the selection and design of boron clusters according to their specific need in molecular materials. The aim of the first funding period is to use different boronclusters as bridges connecting purely organic acceptors and/or donors and to gain a detailed understanding of their electronic properties concerning electron, hole, or spin transfer in the ground or excited state by applying (spectro)electrochemistry, temperature-dependent ESR, steady-state, and time-resolved optical spectroscopy (fs to ns). For a deeper understanding of the underlying mechanisms, the photoinduced dynamics will be modelled by mixed quantum-classical dynamics simulations.
The long-term aims are (I) the assessment of design rules for sophisticated boron-containing optoelectronic materials and (II) the development of versatile boron-based electronic 1D to 3D
compounds.