Fig. 1: Spectroscopic analysis of Fermi level and band edges in Ruddlesden-Popper perovskite (RPP) relative to graphene (G) and gold (Au).
From: Electron tunneling at the molecularly thin 2D perovskite and graphene van der Waals interface
a Structural illustration of monolayer n = 4 RPP ((C4H9NH3)2(CH3NH3)3Pb4I13). b Atomic force microscopy (AFM) image of monolayer and bilayer n =. 4 RPP flakes exfoliated on pure silicon substrate. Scale bar, 1 µm. c Corresponding Kelvin probe force microscopy (KPFM) on the same area of (b). Scale bar, 1 µm. d Real (Ɛ1) and imaginary (Ɛ2) components of the dielectric function for n = 4 RPP; inset shows the extrapolated electronic gap. e Valence band spectroscopy of n = 4 RPP showing valence band edge. f Interfacial energy alignment diagrams of n = 4 RPP, G and Au.
