Design of high-efficiency ultrathin perovskite solar cells using embedded plasmonic Au nanowires and SiO₂ antireflection nanoparticles

This study presents the design of ultrathin perovskite solar cells for flexible applications with reduced toxicity. The limited thickness of the perovskite absorber layer leads to insufficient light absorption and, consequently, reduced device efficiency. To address this limitation, plasmonic Au nanowires embedded within the absorber layer are employed to enhance optical absorption through properly tuned resonance. Three-dimensional (3D) Finite-difference time-domain (FDTD) simulations are used to systematically investigate the effects of nanowire geometry, periodicity, and spatial positioning on light absorption. In addition, SiO₂ nanoparticles are incorporated as antireflection structures to further improve light trapping. The optimum structure demonstrates an overall absorption enhancement of approximately 27.8% compared to the reference device, while accounting for parasitic losses associated with Au nanowires. Quantitative analysis indicates that approximately 19.4% of the improvement arises from Au nanowires, whereas about 8.4% is attributed to the antireflective effect of SiO₂ nanoparticles. The enhancement mechanism is analyzed using extinction cross-section spectrum calculations based on Mie theory, electric field distributions, and surface reflectance. SCAPS simulations of optimum device show that the short-circuit current density increases from 15.85 mA/cm² to 19.87 mA/cm², and the power conversion efficiency rises from 14.88% to 18.40%. Furthermore, applying the proposed structures to absorber layer thicknesses of 250 nm and 400 nm results in PCE improvements of 8.7% and 4.0%, achieving efficiencies of 21.43% and 22.29% under optimum parameters. These findings demonstrate the synergistic effect of combining plasmonic nanostructures with antireflective elements, offering an effective strategy for light management in ultrathin perovskite solar cells and paving the way for high-efficiency flexible photovoltaics.