Optimizing mie resonator shapes for light trapping in perovskite solar cells by transitioning from spherical to hemispherical

Abstract

We present an optimized Mie resonator array (MRA) morphology, evolving from spherical to hemispherical shapes, for efficient broadband light trapping (LT) in perovskite solar cells (PSCs). Unlike previous studies that focused solely on optimizing fixed geometries, our work simultaneously optimizes both the MRA shape and its geometrical parameters to achieve enhanced broadband absorption. This dual optimization approach facilitates strong forward scattering by effectively coupling electric and magnetic resonant modes, significantly improving absorption in the active layer across a wide wavelength range. Additionally, by integrating the LT structure onto the transparent electrode surface, we investigate the impact of surface nanostructuring on optical interactions at the electrode-air and electrode-active layer interfaces. A PSC integrated with a front-mounted MRA LT structure, optimized with a diameter of 300 nm, a spacing of 220 nm, and a sphere parameter (SP; the ratio of the center position of the MRA to its radius, where SP is 0 for a hemisphere and 1 for a sphere) of 0.4, achieves a short-circuit current density (JSC) of 18.56 mA/cm², which is 32.48% higher than that of a planar PSC. The mechanisms behind this broadband absorption enhancement are investigated through detailed analyses of absorption profiles, multipole resonance contributions, and asymmetry parameters. Our findings not only provide a novel strategy for optimizing LT structures in PSCs but also offer insights into how nanostructured interfaces influence light-matter interactions in photovoltaic devices. These results pave the way for new functionalities in applications such as photodetectors, nanoantennas, metasurfaces, and sensors.