Light Absorption Enhancement In Thin-film Silicon Solar Cell By Spherical Ag Nanoparticles On The Back

Metal nanoparticle is much more widely used in the solar cells nowadays. Metal nanoparticle enhances the plasma’s local resonance effect by using this new cell structure. Because making use of the effect of metal nanoparticle generates the oscillation of the surface plasma, gets the absorption of wide spectrum and the conversion of effective light energy, thus enhances the absorption of the active medium efficiently, as well as greatly improves the conversion efficiency of the solar cell.This paper is the research of the absorption efficiency with the finite-different time-domain method to contrast various data using the monocrystalline silicon as the basement structure of the solar cell and spheroidal Ag nanoparticle placed in the back of the solar cell. For example, when the diameters are 80 nm, 100 nm, 120 nm, the silicon base’s length and width are 2μm, the thickness is 800 nm, thus when the diameter is 120 nm, the period is 100 nm as the maximum gain factor g=1.22; And when placing the ones with diameter of 120 nm, contrasting the optical absorption gain G and spheroidal Ag nanoparticle placed in the back, obtaining that the period of reaching the maximum gain is later than placed in the back. Then respectively add the comparison of contrasting the passivation layer of Si3N4 and SiO2, resulting in the refractive index of Si3N4 is higher than SiO2’s by means of simulation. Thus the passivation layer with higher refractive index has a higher light gain. Lights achieve the maximum gain 1.173 as the thickness of Si3N4 is 8nm is higher than the SiO2’s. Respectively simulate the comparison of scattering cross section when using different passivation layers and no passivation layer, working out that scattering cross section with passivation layer stimulates red shift. Adding passivation layer stimulates plasma excitation effect and enhances the light absorption as the scattering is mush in the long position of the long waves. The red shift is obvious because of the refractive index of Si3N4 is higher than SiO2’s.