fig4

Figure 4. (A) Illustration of the role of passivation layers on FF. The green arrow indicates the enhanced charge transfer rate due to the stronger interactions between different layers. (B) PDOS of the interface between (left) pristine, (middle) Sb³⁺ doped and (right) In³⁺doped Cs_0.1FA_0.9PbI₃ perovskite films with TiO₂^[99]. Copyright 2018 Wiley. (C) Theoretical simulation of charge density. (left) The charge density at the interface between the Pb²⁺-based cluster, (middle) the In³⁺-based cluster, and (right) the Sb³⁺-based cluster (C) and the anatase TiO₂ (101) surface, respectively^[99]. Copyright 2018 Wiley. (D) Schematic diagram of band shift of perovskite and TiO₂ in graded heterojunction structure with a mixed and graded interlayer. The negative and the positive circles represent electrons and holes, respectively, and the arrows express their flowing directions^[99]. Copyright 2018 Wiley.