Self-Assembly of Hybrid Materials for Bulk Heterojunction Photovoltaics

Organic- and polymer-based photovoltaics have been the focus of recent study due to inherent advantages afforded by such materials over their crystalline silicon counterparts - advantages such as mechanical flexibility and low-cost, large-area solution processing.  One particularly researched approach is the bulk heterojunction.  In this device architecture, incident solar radiation is typically absorbed by a hole-transporting, electron-donating phase such as a conjugated polymer.  Upon photon absorption, an exciton is generated that diffuses to an interface with a second, electron-accepting phase where it dissociates into an unbound electron and hole.  The electron is transferred to the electron accepting phase where it is transported to a low work function electrode and the hole continues on in the original electron donating phase to the high work function electrode.  Various device geometries are illustrated below:

Coakley, K. M., McGehee, M. D., "Conjugated Polymer Photovoltaic Cells", Chem. Mater. 2004, 16, 4533-4542.

The present work aims to improve upon previous research by utilizing electrostatic self-assembly and virus-mediated biotemplating to incorporate hybrid materials into new device architectures.  Specifically, various nanoscale porous templates will be developed onto which one phase will be deposited.  Upon removal of the template, the second phase will then be adsorbed within the pores in a layer-by-layer fashion.  This versatile approach is broadly applicable to a variety of materials including appropriately-charged polythiophenes (electron donor), various fullerene derivatives (electron acceptor), and biotemplated inorganic II-VI semiconductor nanowires (electron acceptor).