| Summary: | The local plasma resonance of noble metal nanoparticles can significantly enhance the visible light response of wide bandgap semiconductors, but the absorption coefficient of noble metal nanoparticles with small volume and strong scattering is low, which severely limits the photoelectric conversion efficiency. The dipole mirror effect can achieve wide spectrum absorption with high efficiency by a relatively simple metal-insulator-metal (MIM) structure, and it is important for device design and preparation to understand the adjustment principle by the key parameters study. On the basis of AuNPs/TiO2/Au sandwich structure, the variation trends of the electromagnetic field and absorption efficiency with different structural parameters were obtaimed by using the Finite Difference Time Domain (FDTD) to simulate the electric/magnetic field intensity and area of AuNPs/TiO2/Au. The simulation results show that the intermediate dielectric layer can effectively control the light absorption characteristics of the structure. When the dielectric layer thickness is 60 nm, the MIM sandwich structure produces the strongest plasma magnetic resonance and achieves the best visible light absorption efficiency of 92% in wideband (500~850 nm). This study deepens the understanding of the electromagnetic field absorption enhancement mechanism of the dipole mirror effect and provides theoretical guidance for further design of efficient plasma photocatalysts and optoelectronic devices based on MIM sandwich structure.
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