Encapsulation of Nanostructures in a Dielectric Matrix Providing Optical Enhancement in Ultrathin Solar Cells

The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance is widely studied. However, several problems related to the processing complexity and the low performance of the nanostructures have hindered such actions in real‐life devices. Herein, a novel way of introducing gold nanoparticles in a solar cell structure is proposed 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 is verified with the new architecture. Furthermore, the proposed concept in a Cu(In,Ga)Se2 solar cell device is demonstrated, 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. Herein, the study and integration of a novel nanostructure based on Au nanoparticles (NPs) aggregates on the back contact of an ultrathin Cu(In,Ga)Se2 solar cell are developed. The NPs are effectively encapsulated with a dielectric matrix, providing a broadband external quantum efficiency enhancement that translates to a 17.4% improvement of the short‐circuit current density over a reference device.