Hydrogen detector in Kretschmann configuration based on an inorganic perovskite

We theoretically investigate a hydrogen (H\(_2\)) detector in a plasmonic structure involving an inorganic perovskite. The structure is composed of a prism, a silver layer, a perovskite layer (CsPbBr\(_3\)), and a palladium layer (Pd). The palladium layer absorbs H₂, which transforms it into a Pd-H layer. Due to the large difference in dielectric constants between Pd and Pd-H, the reflection versus the incident angle \(\theta\) exhibits great differences (\(\Delta R\)) between the structures with a Pd layer and with a Pd-H layer. Our calculation results show that the working wavelength has a substantial impact on \(\Delta R\). The working wavelength not only affects the dielectric constants of the materials in our structure, but also influences the skin depth of surface plasmon polaritons (SPPs) in the CsPbBr\(_3\) layer, which couple with the Pd or Pd-H layers. A long working wavelength provides a longer skin depth, which couples more energy of the SPPs with the Pd or Pd-H layers. With an increase in Ag layer thickness, the dissipation of our proposed structure reduces the maximum value of \(\Delta R\). According to our calculations, there is an optimal thickness of the CsPbBr\(_3\) layer for which the value of \(\Delta R\) is the largest. The results show the competition between the coupling and the dissipation of the SPP intensity along the direction perpendicular to the layers in the CsPbBr\(_3\) layer. At certain conditions, \(\Delta R\) reaches a value of 0.13, which is about 20% of the reflection value. The detector we designed demonstrates good performance, with many potential applications.