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  • Organic Donor–Acceptor Assemblies form Coaxial p–n Heterojunctions with High Photoconductivity

Organic Donor–Acceptor Assemblies form Coaxial p–n Heterojunctions with High Photoconductivity

Seelam Prasanthkumar, Samrat Ghosh, Vijayakumar C. Nair, Akinori Saeki, Shu Seki, and Ayyappanpillai Ajayaghosh

The formation of coaxial p–n heterojunctions by mesoscale alignment of self-sorted donor and acceptor molecules, important to achieve high photocurrent generation in organic semiconductor-based assemblies, remains a challenging topic. Herein, we show that mixing a p-type p gelator (TTV) with an n-type semiconductor (PBI) results in the formation of self-sorted fibers which are coaxially aligned to form interfacial p–n heterojunctions. UV/Vis absorption spectroscopy, powder X-ray diffraction studies, atomic force microscopy, and Kelvin-probe force microscopy revealed an initial self-sorting at the molecular level and a subsequent mesoscale self-assembly of the resulted supramolecularfibers leading to coaxially aligned p–n heterojunctions. A flash photolysis time-resolved microwave conductivity (FP-TRMC) study revealed a 12-fold enhancement in the anisotropic photoconductivity of TTV/PBI coaxial fibers when compared to the individual assemblies of the donor/acceptor molecules. Angew. Chem. Int. Ed. 2015, 54, 946 –950