Design methodology for selecting optimum plasmonic scattering nanostructures inside CZTS solar cells

Efficiency of CZTS solar cell has made it a good candidate for low cost thin _lm solar cells, due to its low cost and earth abundant materials. Though, its efficiency barely reach 12.6% in 2013, which let great room of improvements required in its efficiency, this could be achieved using plasmonic scattering nanostructures. Designing and selecting optimum plasmonic scattering nanostructures inside active layer of CZTS solar cells would enhance light absorption and increase generated photocurrent. Using Mie theory, we could calculate absorption and scattering cross sections for any plasmonic nanostructure inside solar cells. Calculating and controlling absorption and scattering peaks would manipulate light propagation direction for highest light concentration in CZTS active layer. According to our results, we found that absorption and scattering efficiency of silver nanostructures could be controlled for enhancing light coupling over planar structure only. In addition, using dielectric coating would enhance scattering efficiency and generated more photocurrent over planar structure. All modeling done during this work made using three-dimensional finite element method simulation tool. To verify our results, we compared theoretical results of silver sphere over substrate with previous reported work, and good matching achieved. Using proposed plasmonic nanoscattering structures with certain dimension, pitch, and coating thickness would enhance overall efficiency of CZTS solar cells.