ENHANCING THE LIGHT ABSORPTION OF THIN FILM SOLAR CELLS USING PLASMONIC NANO STRUCTURES

Abstract

Thin film solar cells (TFSC) are in demand on the market of solar cells because of their large scalability and cost effectiveness. However, they suffer from low efficiency. In the last 10 years plasmonic techniques were integrated with solar cell technology to enhance TFSC efficiency. Plasmonic nano particles can trap electromagnetic waves inside the thin cell reaching high efficiency while keeping small thickness. Plasmonic nano particles confine and localize EM-waves in nano range in a technique called Localized Surface Plasmon Resonance (LSPR). Plasmonic properties are very sensitive to size, shape geometry, material, and surrounding medium. In this thesis, we study the effect of different plasmonic nano structures on the enhancement of TFSC power absorbance and short circuit current. We study the effects of using plasmonic sphere-cube hetero-dimer structure as a double system nano particle on the enhancement of TFSC. Double system nano particles are more efficient in light trapping than single nano particles because of plasmonic coupling effect between nano particles in dimer structure. Sphere -cube nano dimer can enhance the absorption of TFSC by trapping light causing broadband absorption spectrum with multi peaks especially in the NIR-IR range which makes sphere -cube nano dimer a good candidate for the intention of TFSC. We performed a parametric study on the geometry, size, and material to determine the best parameter of our solar cell design. We compared the results of our design with reference cells: plain thin solar cell. We calculated ideal short circuit current density for plasmonic solar cell with sphere-cube hetero-dimer with different parameters. To link the optical study of PSC with ideal short circuit current we performed a mathematical model using artificial neural network (ANN). The target of neural network model is fast and efficient predict the short circuit current of fixed solar cell model with changing sphere and cube geometrical parameter. The trained ANN model could solve the problem in small millisecond compared to solving the problem with FDTD simulator. In this thesis, plasmonic asymmetric nano shells like nano eggs, nano cups and nano yolk-shell are studied and compared to core shell nano particles for the enhancement of (TFSC). These asymmetric shells show more near field enhancement and when integrated with (TFSC), the cell absorbance increases.