Control of Nanoarchitectures for Producing Efficient, Large-Area Organic Single-Crystalline Solar Cells
Professor Alejandro L. Briseno
University of Massachusetts
Polymer Science & Engineering, Amherst, MA 01003
In recent years, scientists have placed tremendous effort in trying to produce the ideal architecture for harvesting energy from sunlight. Use of organic semiconductors is of particular interest due to their low-cost, large-scale synthesis, and electronic/molecular tunability. The organic bulk heterojunction (BHJ) solar cell has to date demonstrated the highest efficiency, which now approaches 10%. The reason is due to the high interfacial area between the blended donor and acceptor phases, which enables efficient charge separation and collection. However in principle, the most efficient geometry would employ pillar-like vertical arrays of interdigitated p- and n-type single-crystal organic semiconductor materials. The ideal architecture should have a ~200 nm thick electron donor layer structured as an array of equally spaced nano-columns, with diameters equal to or less than the exciton diffusion length. The realization of this device architecture has yet to be achieved from “all-organic” semiconductor materials.
This presentation will focus on our efforts in producing vertically oriented organic nanopillar arrays. This architecture enables one to investigate charge and photogenerated transport at organic p-n nanowire junctions. We present a new method of growing vertically oriented organic nanostructures onto graphene substrates. Our results indicate that this technique will have implications in the development of highly efficient organic nanostructured solar cells.