Silicon nanowire-incorporated efficient and flexible PEDOT:PSS/silicon hybrid solar cells†

Abstract

The global demand for renewable energy sources has intensified the quest for innovative and inexpensive solar cell technologies. Employing thin crystalline silicon (c-Si) is of great interest in these advancements. Herein, the integration of organic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and nanostructured thin-flexible Si wafers (∼50 μm) is investigated to harness their synergies in fabricating mechanically flexible hybrid heterojunction solar cells (HHSCs). Flexible Si wafers were prepared through alkali etching, followed by incorporation of silicon nanowires (SiNW) on one side of the thin wafers using a single-step silver (Ag)-assisted chemical etching (Ag-ACE) process at room temperature. The SiNW-incorporated flexible solar cells demonstrated an impressive power conversion efficiency (PCE: 9.0%) even with the simple design owing to enhanced light absorption in a broad spectral range. It is found that the SiNW length and polymer layer thickness play a critical role in defining the trade-off among the optoelectronic, junction and solar cell parameters. The SiNW with a 170 ± 20 nm length and PEDOT:PSS with a 100 ± 10 nm layer is the optimal combination for the best solar cell parameters. The enhanced light trapping and charge generation rate are also confirmed by finite-difference time-domain (FDTD) simulation. The detailed analysis of light trapping, junction properties, surface passivation, device performance parameters and their co-relation are discussed. Our study demonstrates the SiNW-incorporated flexible and efficient PEDOT:PSS/n-Si HHSCs, which can not only lead to the advancement of low-cost photovoltaics but also offer potential for diverse applications, from portable electronics to wearable technology.