fig3

Figure 3. KPFM images of the (A) ctrl perovskite film and (B) target perovskite film. CPD distribution extracted from KPFM data of the (C) ctrl perovskite films and (D) target perovskite films; (E) PL spectra and (F) TRPL decay characteristics of perovskite films with and without FTAC modification (sample structure: ITO/SnO₂/perovskite/HTL and ITO/SnO₂/perovskite/ FTAC/HTL). KPFM: Kelvin probe force microscopy; PL: photoluminescence; TRPL: time-resolved PL; FTAC: (ferrocenylmethyl)trimethylammonium chloride; ITO: indium tin oxide; HTL: hole transport layer; CPD: contact potential difference.