Nanoscale light focusing of colloidal nanostructures for enhanced silicon solar cells

Abstract

Photonic nanostructures have achieved nanoscale optical field modulation and ultra-low refractive index effects that traditional thin film materials cannot reach, providing a new direction for optical management and carrier management of photovoltaic devices. Dielectric nanostructures can reduce the surface light reflection of photovoltaic devices, similar to traditional antireflection films. Therefore, dielectric nanostructures are usually equivalent to the equivalent refractive index theory at the macro level. However, the macroscopic refractive index equivalent cannot reflect the manipulation ability of nanoscale light fields, and the influence of the nanoscale light field distribution on the photo-carrier generation and transport is usually ignored. Here, we introduce the self-assembly process of dielectric nanostructures on photovoltaic devices, which may lead to the controllable assembly of the density and number of layers on polycrystalline silicon solar cells. Based on this strategy, we investigate the enhancement effect of SiO2 nanosphere coating on textured silicon solar cells by systematically changing assembly conditions. Research has found that tightly packed SiO2 nanosphere monolayers generate a maximum relative efficiency improvement of 9.35%. This efficiency increase is attributed to the simultaneous enhancement of short-circuit current density and fill factor, which is different from the antireflection effect reported previously. Further, through semiconductor simulations, we theoretically analyzed the impact of nanoscale light focusing on the performance of photovoltaic devices. We explored the reasons for the changes in photocurrent, fill factor, and efficiency, providing ideas for more efficient nanoscale light focusing design and improving the performance of photovoltaic devices in the future.