Numerical analysis of monocrystalline silicon solar cells with fine nanoimprinted textured surface

Abstract

We investigated the surface reflectance of nanoimprinted textures on silicon. Zirconium oxide, which is a wide-bandgap inorganic dielectric material, was used as the texturing material. We performed several calculations to optimize the textures for the production of high-efficiency bulk-type monocrystalline silicon solar cells. Our analysis revealed that nanoimprinted textured solar cells exhibit a lower reverse saturation current density than a solar cell with a conventional etched texture. It was also confirmed that the photocarrier generation rate for a solar cell with a submicron-scale nanoimprinted texture has little dependence on the texture shape. Furthermore, the weighted average reflectance of an optimized nanoimprinted textured solar cell was substantially reduced to 3.72%, suggesting that texture formation by nanoimprint lithography is an extremely effective technology for producing high-efficiency solar cells at a low cost.

Low surface reflectance by nanoimprinted texture with silicon-rich silicon nitride layer

“…The surface reflectance shown in figure 10 shows a high value remains in the short wavelength region. The height of the ZnO moth-eye structure, which strongly influences the surface reflectance in the short wavelength region, should be as high as 200 nm according to [25] while this report has it around 100 nm. In addition, the refractive index of ZnO usually reaches 1.9 at the 790 nm wavelength while this report found that the moth-eye part was only 1.64 at the 605 nm wavelength and 1.62 at the 790 nm wavelength.…”

“…The difference of the refractive index at the interface has to be minimized to suppress the surface reflection. In this study, we proposed the layer insertion to reduce such reflection between ZnO and c-Si, as shown in the above section, and the refractive index of the inserted layer should be around 3 according to [25]. In addition, the utilized Si-rich SiN should be around 40 nm in thickness.…”

Transfer durability of high aspect ratio moth-eye structure on glassy carbon mold using release agent

“…Due to a dramatic increase of devices with display screens and the wide adoption of solar panels, the demand for an antireflection structure is increasing. [1][2][3][4] A general anti-reflection structure is a multilayer film, which is both time and cost intensive to produce. In addition, there is a limit to the wavelength and incident angle at which reflection can be suppressed.…”