Synergistic effects of Mie resonances and anti-reflections on enhanced absorption in organic solar cells

Abstract

We demonstrate an efficient light trapping (LT) and anti-reflection (AR) structure consisting of an array of dielectric subwavelength pyramids (ADSP) for enhanced light absorption in organic solar cells (OSCs). The overlapping electric dipole and magnetic dipole resonances provide strongly directional forward scattering at short wavelengths, extending the optical path length within the active layer of the OSC. In addition to strong light scattering, the gradient refractive index profile of the ADSP enables an AR effect over a wide range of wavelengths. The combined effect of strong forward-scattering and broadband AR from the ADSP significantly enhances absorption in the active layer of the OSC, which is enabled by finding optimal geometrical parameters of the ADSP. A short-circuit current density (JSC) of 27.83 mA/cm2 is achieved in the OSC with the incorporation of the ADSP, representing an 8.37% enhancement compared to a flat OSC. Furthermore, we investigate the contributions of resonant and non-resonant multipolar moments to forward scattering in the ADSP. The controlled excitation of multipole resonances in the ADSP offers pathways to significantly enhanced performance in various applications, including other thin-film solar cells, metasurfaces, sensors, nanoantennas, and photodetectors.