Theoretical insights into highly transparent multi-sized conducting films with high-haze and wide-angular scattering for thin film solar cells

Abstract

Recent advances in light trapping schemes open up new gateways for enhancing the absorption of solar energy that approaches and overcomes the Yablonovitch 4n2 limit based on isotropic Lambertian scatterers. Achieving wide-angular scattering while maintaining a strong scattering intensity is the key to realize a Lambertian-like scatterer that may have a great potential to approach the absorption upper limit. However, few current light trapping strategies can experimentally extend the scattering angular domains in absorbers while maintaining a high scattering intensity. In this paper, we theoretically and experimentally investigate multi-sized transparent conducting oxide (TCO) films, which are comprised of micro-sized, magnetron-sputtered and chemically etched aluminum-doped zinc oxide (ZnO:Al), coated with metal organic chemical vapor deposition (MOCVD) deposited nano-sized, boron-doped zinc oxide (ZnO:B) pyramids. We demonstrate that the multi-sized TCOs in this study can efficiently increase the total transmittance in the visible spectral range, enhance the scattering intensity, successfully extend the scattering angular domains to 90°, and improve the short-circuit current density and power output of solar cells. The combination of these factors endows the TCOs with the significant potential for realizing a Lambertian-like scatterer. Accordingly, the multi-sized architecture may inspire fresh ideas for realizing more innovative light-trapping architectures.