Optimization of stacked di-electric bilayer at rear side of PERC solar cell for better light management

Selection of suitable metal-oxide type dielectric passivation layer enhances the open circuit voltage of the Passivated Emitter Rear Contact (PERC) solar cell to a great extent. Incorporation of Aluminium oxide (Al2O3) as passivation layer has been a common practice for the fabrication of PERC solar cell both in industry and research laboratory. However, the optically unmatched refractive index of Al2O3 does not redirect the transmitted photons (Wavelength ranging 900nm to 1100nm) through ~180µm thick c-Si p-type substrate to the solar cell. Hafnium oxide (HfO2) with optically matched RI exhibits comparable passivation property. If HfO2 can be used instead of Al2O3 increase the possibility of redirecting the transmitted photons to the solar cell again without compromising the passivation property, which may increases the solar cell performance. It has been observed that 93% transmitted photons can be reflected back to the solar cell structure for optimized double dielectric stack.