Organic semiconductor nanomaterials have gained a great deal of attention due to their broad applications in electronic and optoelectronic devices, as well as their low cost solution processing and flexibility for large area manufacturing. Particularly, one-dimensional nanomaterials (e.g., nanowires or nanofibers) self-assembled from organic semiconductor molecules often provide enhanced photoconductive performance, mostly due to their wide interface for electron donor-acceptor (D-A) modification, as well as the long range p-p stacking arrangement along the long axis that enables high charge mobility through p-electron delocalization. However, it still remains challenging to achieve high photoconductivity for organic nanofibril materials. One such challenge lies in the control of the back electron transfer, i.e., charge recombination. In this presentation, we report on a systematic approach to fabricate highly photoconductive nanofibril heterojunction system, by combining the control of several material properties and processing parameters, including side chain structure and chemical property (hydrophilic vs. hydrophobic) of the building block molecules, temperature and solvent selection for nanofiber growth, post growth annealing of the nanofibril D-A composites in solvent vapor. Optimization of these factors leads to construction of a set of nanofibril D-A heterojunctions that provide the maximal photoconductivity. The reported fabrication approach is expected to be adaptable to other organic nanofibril systems to achieve high photoconductivity, which can further be employed in the development of high-performance organic solar cells.

Systematic interface engineering to approach highly photoconductive nanofibril heterojunctions

246th National Meeting (2013)

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