Effects of interfacial oxide layer thickness and interface states on conversion efficiency of SnO2/ SiO2/Si(N) solar cells

Abstract

The interfacial layer in a Schottky barrier solar cell plays an important role in determining the short circuit current, open circuit voltage, fill factor and efficiency of the cell. In this paper, we studied the effects of interfacial oxide layer thickness, interface state density and Ф0 (the level above the valence band to which surface states are filled in isolated semiconductor) on the open circuit voltage and efficiency of the SnO2/SiO2/Si (N) solar cells. From our analysis, we have found that the efficiency of the cell increases at first with the interfacial oxide layer thickness δ, and after acquiring a maximum value falls with a further increase of δ. We have optimized the interfacial layer thickness for maximum efficiency. The solar cell current–voltage characteristics under illumination are also computed for different values of insulator thickness δ. The results obtained by numerical simulation using Matlab programs are presented and discussed. The SnO2/SiO2/Si (N) solar cells, in which the interfacial oxide layer thickness is optimized to 21 A°, have an average open circuit voltage of 0.62 V and a short circuit current of 36 mA/cm2. The calculated conversion efficiency of the cells can be as high as 17.5 %.