Fig. 1

Observation of vertical phase distribution and tailoring in Q-2D perovskite films. a PL spectra of Q-2D perovskite films on different substrates excited from the back side (substrate side). The inset is the PL spectra of Q-2D perovskite films on different substrates excited from the front side; b the zeta potential of PEDOT:PSS and BrB-PEDOT:PSS; c the schematic of covalent modification on PEDOT:PSS via a molecule of 4-bromobenzenediazonium tetrafluoroborate. Contact angle images of water on: d PEDOT:PSS and e BrB-PEDOT:PSS. f XPS depth profiles of C/Pb atom ratios as a function of etching time for the Q-2D films. (etching direction: surface of the perovskite film to the substrate side)