Surface Plasmon Enhanced Polymer Solar Cells

Organic photovoltaic(OPV) cells are attracting much attention due to their potential for low cost, simple manufacture process, easy realization of large-size and flexibility. However, compared to inorganic solar cells, power conversion efficiency(PCE) in OPVs must be addressed due to limitations including absorption transparence in the near-infrared(NIR) region for most of organic/polymer active layers, low carrier mobility of organic materials, large energy loss generated with the charge separation, and mismatched energy levels between the donor and the accepter. Therefore, promoting light absorption is one of key points to raise the PCE. Using new materials with low band gaps has efficiently promoted light absorption in the NIR region. Another effective approach to enhance absorption in an active layer is utilizing surface plasmon polaritons(SPPs), which has been widely used in organic photovoltaic cells in recent years.Au and Ag nanoparticles have been widely used to promote absorption in organic active layer, which are often fabricated by using approaches of thermal evaporation, laser ablation, electron beam lithography, focused ion beam milling, electricity pulse deposition, etc. In this thesis, spherical and bone-like Au nanoparticles(NPs) were synthesized with a seed-mediated growth approach and then these Au NPs were transferred onto ITO anode through a self-assembly approach, forming a series of plasmon-enhanced OPVs. PCE can efficiently enhance from 3.18% to 3.78% and 4.06% with the introduction of the spherical and bone-like Au NPs into OPVs. The principle and origin of Au NPs on improving OPV performances were deeply explored in this work.