A study of back electrode stacked with low cost reflective layers for high-efficiency thin-film silicon solar cell

In this study, commercially available white paint is used as a pigmented dielectric reflector (PDR) in the fabrication of a low-cost back electrode stack with an Al-doped ZnO (AZO) layer for thin-film silicon solar cell applications. An initial AZO film was deposited by the radio-frequency magnetron sputtering method. In order to obtain the highest transmittance and lowest resistivity of AZO film, process parameters such as sputtering power and substrate temperature were investigated. The optimal 100-nm-thick AZO film with low resistivity and high transmittance in the visible region are 6.4 × 10^-3 Ω·cm and above 80%, respectively. Using glue-like white paint doped withTiO2 nanoparticles as the PDR enhances the external quantum efficiency (EQE) of a microcrystalline silicon absorptive layer owing to the doped white particles improving Fabry-Pérot interference (FPI), which raises reflectance and scattering ability. To realize the cost down requirement, decreasing the noble metal film thickness such as a 30-nm-thick silver reflector film, and a small doping particle diameter (D50 = 135 nm) and a high solid content (20%) lead to FPI improvement and a great EQE, which is attributed to improved scattering and reflectivity because of optimum diameter (Dopt) and thicker PDR film. The results indicate that white paint can be used as a reflector coating in low-cost back-electrode structures in high-performance electronics.