Figure S1, S2, S3, S4, S5, S6

Figure S1. CsI different thickness of (a) PCE; (b) FF; (C) Jsc; (d) Voc. Figure S2. CsCl different thickness of (a) PCE; (b) FF; (C) Jsc; (d) Voc. Figure S3. CsBr different thickness of (a) PCE; (b) FF; (C) Jsc; (d) Voc. Figure S4. Hysteresis of the control and CsX-modified PSCs. F and R represent forward and reverse scans, respectively. Figure S5. (a). Control group film grain size distribution map; (b). CsI modified film grain size distribution map; (c). CsCl modified film grain size distribution map; (d). CsBr modified film grain size distribution map. Figure S6. Energy Dispersive Spectrometer (EDS) of the perovskite films without/with CsX (X=I、Cl、Br) layer modification.