Fig. 1: Development of the perovskite-based Tamm plasmon structure.
a Cross-sectional HAADF-STEM image of the perovskite-based Tamm plasmon structure. Left: Magnified image of the metal-quasi-2D perovskite interface. The scale bar shows 50 nm. A similar structure is fabricated as the reference-perovskite structure (without TiO2/SiO2 layer pairs) to ensure results are not affected by unwanted effects, e.g., PL quenching due to metal deposition. The thickness of each layer is TiO2 = (70 ± 2) nm, SiO2 = (90 ± 2) nm, quasi-2D perovskite + PVK = (34 ± 5) nm, Ag = (100 ± 5) nm. b EDX chemical map of perovskite-based Tamm plasmon structure. Areas rich in Ag, Cs, Pb, Br, C, Si and Ti are marked in the legend. The scale bar shows 200 nm. The observed halo features at the titanium (Ti)-rich interface are found to be a slight compositional gradient of Ti, while the oxygen composition remains constant at the interface. c Simulated electric field enhancement, \(\frac{{\left|E\right|}^{2}}{{\left|{E}_{0}\right|}^{2}}\) of the narrow-angle-Tamm-plasmon-perovskite structure. d Experimental optimisation of perovskite-based Tamm-plasmon structure by varying the perovskite thicknesses between 20 nm to 54 nm (Tamm plasmon resonance wavelength best fitted with transfer matrix model to estimate thickness of perovskite). Tamm plasmon resonance dip acquired from reflectance measurements at 8°. PL of quasi-2D perovskite thin film on glass is shown as dashed line. e Tamm plasmon resonance wavelength at 8° versus perovskite film thickness. Perovskite thickness is measured under AFM (solid line) and estimated from Tamm plasmon resonance wavelength best fitted with simulation (dashed line). Inset: schematic of the perovskite-based Tamm-plasmon structure with a green arrow indicating the quasi-2D perovskite layer.
