Simultaneous Interfacial Defect Passivation and Bottom-Up Excess PbI Management via Rubidium Chloride in Highly Efficient Perovskite Solar Cells with Suppressed Hysteresis.

In halide perovskite solar cells (PSCs), moderate lead iodide (PbI) can enhance device efficiency by providing some passivation effects, but extremely active PbI leads to the current density-voltage hysteresis effect and device instability. In addition, defects distributed on the buried interface of tin oxide (SnO)/perovskite will lead to the photogenerated carrier recombination. Here, rubidium chloride (RbCl) is introduced at the buried SnO/perovskite interface, which not only acts as an interfacial passivator to interact with the uncoordinated tin ions (Sn) and fill the oxygen vacancy on the SnO surface but also converts PbI into an inactive (PbI)RbCl compound to stabilize the perovskite phase via a bottom-up evolution effect. These synergistic effects deliver a champion PCE of 22.13% with suppressed hysteresis for the W RbCl PSCs, in combination with enhanced environmental and thermal stability. This work demonstrates that the interfacial defect passivation and bottom-up excess PbI management using RbCl modifiers are promising strategies to address the outstanding challenges associated with PSCs.