The band gap is a key property in the design of optoelectronic materials, and it is traditionally modulated via molecular structural modifications (e.g. substituents, heteroatoms, ring fusion). Previously, we have shown three-point (DAD…ADA) H-bonding between π-donors and π-acceptors as a tool to produce bicomponent semiconductors. Apart from controlling self-assembly, the H-bonding also affects the energy levels due to polarization via proton transfer, and thus could be used as another handle for band-gap engineering.<br/><br/>In this talk, we will present unidirectional (DD...AA) H-bonding as a tool to drive the self-assembly and engineer the band gap of weak charge transfer (CT) complexes (based on diindolopyrrole and various o-quinones) over a wide range (0.8 – 1.7 eV), and some current work involving stronger complexes. Such assemblies can be initiated via solid, solution, and even gas phase mixing of donor and acceptor components. Using the latter, we fabricated bicomponent thin film transistors via vacuum deposition which exhibited unusual “double-dip” characteristics that are of potential interest for memory applications. We will also present some latest results on an H-bonded NDI (a popular n-type conducting material) exhibiting the highest solid-state fluorescence among NDI small molecules, which is remarkable since H-bonding is generally known to decrease emission.

Effects of hydrogen-bonding on the properties of organic semiconductors

ACS Spring Meeting 2021

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