Metastructure Engineering with Ruddlesden-Popper 2D Perovskites: Stability, Flexibility, and Quality Factor Trade-Offs

Abstract

In this study, we investigate the opto-electro-mechanical properties, thermodynamic stability, and moisture stability of the Ruddlesden-Popper (RP) two-dimensional perovskites of L₂PbI₄ (L = PEA, FPEA, BA, and BZA) using density functional theory. The goal is to explore their potential application in metastructures. The results show that the stability of FPEA₂PbI₄ is better than that of PEA₂PbI₄, BA₂PbI₄, and BZA₂PbI₄ due to the replacement of a hydrogen atom with a fluorine atom. On the other hand, BA₂PbI₄ is more flexible than other materials because it lacks an aromatic ring in its spacer cation, but it is less stable. We introduce a new kind of metastructure composed of an RP perovskite film and conduct an extensive investigation of the quasi-bound states in the continuum (q-BIC) characteristics by near-field analysis and multipole decomposition calculations. The q-BIC resonances in BZA₂PBI₄ have a greater quality factor due to its larger refractive index in comparison to other materials. Therefore, based on these results, the perovskite materials can be selected for the metastructures from different aspects of stability, flexibility, and refractive index.

Figure 1

Schematic structure of (a) PEA, (b) FPEA, (c) BZA, and (d) BA as spacer cations in RP 2D perovskites.

Figure 2

Band structure and bandgap energy of (a) PEA₂PbI₄, (b) FPEA₂PbI₄, (c) BA₂PbI₄, and (d) BZA₂PbI₄.

Figure 3

Complex refractive index of (a) PEA₂PbI₄, (b) FPEA₂PbI₄, (c) BA₂PbI₄, and (d) BZA₂PbI₄.

Figure 4

(a) Schematic of the suggested design, (b) symmetric unit cell, and (c) asymmetric unit cell.

Figure 5

(a) Transmittance spectrum under y-polarization for the symmetry structure, (b) transmittance spectrum under y-polarization for asymmetry structure, (c) Fano fitting of mode A₂ in PEA₂PbI₄ for d = 0.5, (d) Fano fitting of mode B₂ in PEA₂PbI₄ for d = 0.5, (e) transmittance spectrum under x-polarization for the symmetry structure, (f) transmittance spectrum under x-polarization for the asymmetry structure, (g) Fano fitting of mode A₁ in PEA₂PbI₄ for d = 0.5, and (h) Fano fitting of mode B₁ in PEA₂PbI₄ for d = 0.5.

Figure 6

Color maps of displacement currents, electric and magnetic fields, and vector distributions in the x–y plane for (a) A₁, (b) B₁, (c) A₂, and (d) B₂.