Virus-Templated Nanostructured Titania-Lead Sulfide Heterojunction Solar Cells

Current titania and quantum dot solar cells are generally structured in a bilayer.  However, a bicontinuous nanostructured morphology promotes more efficient exciton dissociation and charge transport.  Such nanostructured composites are difficult to obtain without the use of energy intensive processes to create regular structures, and often nanopores cannot be obtained.  The M13 bacteriophage, which is easy and inexpensive to amplify and has the ability to template a variety of metallic and oxide materials, can be organized into a nanoporous film via layer-by-layer assembly.  Here, we use the bacteriophage films as a scaffold to generate a titania nanomesh and infiltrate it with lead sulfide quantum dots.  The porosity of the virus-templated titania film can be tuned as a function of the titania synthesis time.  These parameters, as well as the nature and infiltration method of lead sulfide quantum dots, affect the final heterojunction solar cell performance.  In addition, the continuous pathways created in the virus-templated titania film reduce recombination compared to traditional titania paste films.  In summary, we demonstrate that M13 bacteriophages represent a promising tool to organize nanomaterials and create continuous nanostructures that can lead to efficient photovoltaic devices.