Encapsulation of nanostructures in a dielectric matrix providing optical enhancement in ultrathin solar cells

Abstract

The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance has been widely studied. However, several problems related with the processing complexity and the low performance of the nanostructures have hindered such actions in reallife devices. In this work, we propose a novel way of introducing gold nanoparticles in a solar cell structure in which the nanostructures are encapsulated with a dielectric layer, shielding them from high temperatures and harsh growth processing conditions of the remaining device. Through optical simulations, an enhancement of the effective optical path length of approximately four times the nominal thickness of the absorber layer was verified with the new architecture. Furthermore, we demonstrate the proposed concept in a Cu(In,Ga)Se2 solar cell device, where the short circuit current density is increased by 17.4 %. The novel structure presented in this work is achieved by combining a bottom-up chemical approach of depositing the nanostructures with a top-down photolithographic process, which allows for an electrical contact.