Enhanced absorption in organic solar cells via combined anti-reflection and Mie resonance effects in subwavelength ellipsoidal dielectric nanostructures

This study presents subwavelength ellipsoidal dielectric nanostructures (SEDNs) to enhance absorption in organic solar cells (OSCs) through the combined effects of broadband anti-reflection (AR) and Mie scattering. Strong forward-directed scattering at shorter wavelengths is produced by the simultaneous excitation of both electric and magnetic moments in the SEDN, thereby lengthening the optical path length inside the active layer. Additionally, the SEDNs reduce reflection over a broad wavelength range, further enhancing absorption. By fine-tuning the structural parameters of the SEDN, including a minor axis diameter of 100 nm, a spacing of 30 nm, and an aspect ratio of 3.6 for TE polarization, a short-circuit current density (J_SC) of 28.11 mA/cm² is achieved, representing an 9.46% improvement over planar OSCs. Light scattering is analyzed through multipolar decomposition, while the AR effect is studied using optical admittance analysis. The proposed approaches not only offer performance enhancements for applications such as thin-film solar cells, photodetectors, nanoantennas, and metasurfaces, but also show potential for polarization-sensitive applications including bio-imaging, defect analysis, and optical security systems.