Quantum dot sensitized ZnO nanowire-P3HT hybrid photovoltaics
A hybrid, nanostructured solar cell architecture has been designed, described, fabricated and characterized. ZnO nanowires were synthesized using thermal chemical vapor deposition to act as a high energy photon absorber scaffold and electron transport pathway. InP-ZnS core-shell quantum dots were attached to the nanowires via surface chemistry to act as a high-efficiency sensitizing absorption medium. A ligand exchange procedure was performed to cap the quantum dots with mercaptopropionic acid for improved adhesion to ZnO nanowires and improved electrical properties. Experimentation was performed to optimize the surface chemistry adhesion of the ligand exchange and quantum dot-nanowire adhesion. A thoroughly-filled P3HT matrix was drop coated selectively and annealed into the quantum dot sensitized nanowire array to serve as a hole capture and transport, absorption, and planarizing medium. Characterization was performed throughout device fabrication using SEM, TEM, XRD, PL spectroscopy, Raman spectroscopy, UV-Vis spectroscopy, and electrical measurements. A dense monolayer of quantum dots was deposited and imaged via HRTEM. PL quenching of quantum dots in P3HT was observed. The viability and advantages of quantum dot sensitization of a hybrid ZnO nanowire-P3HT hybrid were shown via PL, UV-Vis and device electrical measurements.