Improving Light Absorption in a Perovskite/Si Tandem Solar Cell via Light Scattering and UV‐Down Shifting by a Mixture of SiO2 Nanoparticles and Phosphors

The optical properties of a textured antireflective coating (ARC) polymeric film are engineered by combining the down‐conversion effect of large phosphor particles and the multiple scattering effect of SiO2 nanoparticles. In order to address the parasitic absorption of ultraviolet (UV) light, phosphors are added to convert UV light to visible light. However, the embedded phosphors increase the reflectance of the ARC film, due to the large particle size (>5 µm) and high refractive index (n ≈ 1.9) of phosphors. Such a backward scattering problem of phosphors is compensated by adding spherical SiO2 nanoparticles. Experimental and computational results show that SiO2 nanoparticles in the ARC film decrease the reflectance by increasing the diffuse transmittance. This optically engineered ARC film successfully promotes the light absorption of the perovskite/silicon tandem solar cell, leading to the improvement of power conversion efficiency of the tandem cell from 22.48% to 23.50%. A combination of two particles (phosphors and SiO2 nanoparticles) in the textured poly (dimethylsiloxane) film provides additional light by converting UV light and improves diffuse transmittance by multiple scattering. Thus, the total amount of light absorbed by the perovskite and Si increases, resulting in power conversion efficiency improvement of the perovskite/Si tandem solar cell.