Sequential resonance engineering of Fabry-Perot and Mie modes for enhanced absorption in ITO-free organic solar cells

초록

We present a broadband light-trapping (LT) approach for ITO-free organic solar cells (OSCs), developed through the sequential engineering of Fabry-Perot (FP) resonance and multi-resonant Mie scattering. The front dielectric-metal (DM) electrode, consisting of optimized MoO3 and Ag layers, enhances the FP cavity effect and yields constructive interference across multiple wavelengths, resulting in a short-circuit current density (JSC) of 25.83 mA/cm2. To further enhance light harvesting, a TiO2 nanosphere array (NSA) is incorporated to enable broadband Mie scattering and extend the optical path within the active layer. With optimized geometrical parameters, a diameter of 160 nm and spacing of 220 nm, the TiO2 NSA increases the JSC to 26.74 mA/cm2, corresponding to a 3.52 % improvement over the planar structure. Multipolar resonance analysis reveals that forward scattering is primarily governed by electric and magnetic dipole modes, which shape the spectral response and field distribution. These results offer valuable insights and a versatile framework for light-management applicable to a broad range of optoelectronic devices, including thin-film solar cells, photodetectors, and nanoantennas.

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