Research Project
M13 bacteriophages are filamentous viruses that are about 1 µm long and 5-6 nm in diameter. The virus capsid consists of five different kinds of proteins: p3 and p6 at one end of the virus, p9 and p7 at the other end, and p8 along the major axis. The p3, p9, and p8 proteins can be genetically engineered to display a short foreign peptide. By using peptides with a specific affinity for a material, previously selected through phage display, a multi-functional nanomaterial template structure is created.
We are currently functionalizing the p8 coat to attach semiconductor and metal nanoparticles. When nanoparticles attach to the surface of the M13, they form a chain around the M13 virus. This pearl necklace type of structure can be used as nanowires. We are currently using CdSe quantum dots to form nanowires for application in solar cells. While colloidal semiconductor quantum dot (QD) solar cells (inorganic or polymer-QD hydrids) have been demonstrated and high efficiencies have been predicted, the lack of a continuous path for carriers generated in the QDs to the contacts remains a large problem. In our case, we propose to solve the problem by functionalizing the p3 end of the M13 bacteriophage to attach to the contact material while templating the QDs on the p8 major coat, thus creating a direct path for carriers to the contacts.
In order to create a solar cell, photo-excited excitons (bound electron hole pairs) must be separated. While previous work has been done using a type II heterojunction, the preferred method is a p-n junction. However, doping the quantum dots has been extremely difficult due to their self-purifying nature as dopants are easily pushed out to the surface. By using nanoparticles as "dopants" in the 1D quantum dot ensemble assembled along an M13 phage, it may be possible to overcome the challenge of doping individual quantum dots. We use M13 to make quantum dot chains in efforts to make "doped" semiconductor nanowires.