Plasmonic Enhancement In Hybrid Organic/Si Heterojuction Solar Cells Based On Gold Nanostructures

Hybrid organic-inorganic composites combining the advantage of organic and inorganic have emerged as promising candidates for cost-effective photovoltaics(PVs). Silicon-based hybrid solar cells with the power conversion efficiency exceeding 17% play a key role in this field. Si nanostructures(NSs) such as nanowire array can provide a low reflectivity over a broad range of solar spectrum, which promise them as efficient light harvesting substrates. However, the light-trapping nanostructures significantly enlarge the surface area of Si substrates and result in additional surface trap states, leading to a high surface recombination velocity. Alternatively, antireflection layers such as SiNx are typically deposited by plasma enhanced chemical vapor deposition(PECVD) method, which can suppress light reflection. Unfortunately, this technique is incompatible with the organic layer on Si. Therefore, absorption enhancement is one of the primary challenges to achieve high efficient organic/Si solar cells. Most recently, the metallic NSs with novel plasmonic properties in terms of optical response have been widely employed in the PV field. The whole thesis includes three parts:Firstly, we proposed poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)(PEDOT:PSS)/Au NPs composite films to effectively enhance the light harvesting properties for organic/Si PVs. Au nanoparticles(NPs) were prepared by simple and cost-effective solution-processed techniques. With tuning the size of the particle, the scatting and excitation intensity dramatically affect the light coupling in the conducting polymer layer. The finite different time domain(FDTD) simulation as also used for exploring the surface plsmonic effect theoretically.Secondly, the composite of Au NPs and grapheme oxide was utilized into the hybrid solar cell. The addition of grapheme oxide greatly improves the concentration of Au NPs without aggregation.Finally, the effect of gold nanorod(Au NR) induced surface plasmons on the performance of devices was investigated by introducing hot carrier generation. When the hot electron with sufficient momentum was generated in the AuNR indirect contact with silicon where an interface potential is formed, the excited electron in the nanostructures might have sufficient energy to pass the barrier, which will induce photocurrent of the device.