Effect of anti-reflecting layers on device performance of SWCNTs/Si hetero-junction hybrid solar cells

Abstract

Single wall carbon nano-tubes/Silicon (SWCNTs-Si) solar cells have the ability of being an ideal substitute to the expensive crystalline based Silicon solar cells because of promising cell efficiency and cost effectiveness. Single wall carbon nanotubes (SWCNTs) thin films are deposited on n-type silicon substrate to obtain heterojunction solar cells. To enhance the performance of these heterojunction solar cells Molybdenum Oxide and Tin Chloride are deposited on SWCNTs/Si substrates respectively. It has been confirmed from Raman spectroscopy that the doping of MoOx has enhanced p type behaviour of SWCNTs, MoOx layer acts as an anti-reflection layer and protects the n-Si and SWCNTs interface from deposition of oxides. While on the other hand SnCl2 acts as antireflection layer, enhances p-type doping of SWCNTs and suppression of recombination. Three hybrid heterojunction solar cells were fabricated by using MoOx on SWCNTs/Si, SnCl2 on SWCNTs/Si and both MoOx and SnCl2 on SWCNTs/Si, respectively. For structural analysis we have performed X-Ray diffraction (XRD) and Raman analysis. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) are performed for surface analysis which confirms the smooth protected layers of MoOx and SnCl2; furthermore confirmed the presence of deposited metal oxide MoOx and SnCl2. Optical properties such as reflectance of thin films studies by UV visible spectroscopy. Maximum efficiency of 8.2% has been obtained by using both MoOx and SnCl2 on SWCNTs/Si solar cell.