Toward Plasmon Enhanced Organic Photovoltaics: A Study of Nanoparticle Size and Shape
This thesis reports the functionalization of metal nanoparticles to allow for solubility in organic solvents used in solar cell fabrication. Functionalization of the nanoparticles using poly(ethylene glycol) methyl ether thiol (PEG-SH) allows for the phase transfer of the nanoparticles from aqueous solution to organic solvents. Once functionalized it was found that nanoprisms will undergo a shape change. This change in morphology was investigated using UV-Vis measurements, transmission electron microscopy (TEM), and X-ray Absorption Near Edge Structure (XANES) measurements and a mechanism for the shape degradation is presented. The PEG functionalization procedure can be applied to other types of metal nanoparticles and once soluble, these particles were incorporated into the active layer of the BHJ cells. It has been found that the PEG functionalized particles do not improve the cell efficiency, but they do affect the cell performance. The addition of the particles does not influence the open circuit voltage, but it does affect the current density of the devices. This suggests that the particles may be acting as electron traps, not allowing current to flow efficiently through the device. This shows that while the PEG-ylation of the particles is effective at solubilising them into useful organic solvents, the thickness of the PEG layer on the nanoparticles may not provide protection from electrons and allow for effective charge transfer throughout the solar cell.
DegreeMaster of Science (M.Sc.)
Copyright DateNovember 2013
Organic Photovoltaics, Nanoparticles, Plasmon Resonance