Unraveling the Reasons Behind SnO₂/Perovskite Defects and Their Cure Through Multifunctional Ti₃C₂T_X

The rationale for low performances in perovskite solar cells with buried interface still needs to be clarified, owing to the complicated physiochemistry of metal oxides/perovskite interface, and literature offers a meager knowledge about the reactions at this interface. While exploring the SnO2/perovskite interfacial interactions, the reasons behind deteriorating perovskite at the interface are comprehensively investigated, and it is revealed that the PbI2 residue and metallic Pb-0 are the byproducts of this decomposed perovskite. Introducing an optimized amount of Ti3C2TX at the SnO2/perovskite interface detaches the SnO2 hydroxyls, which are found to be responsible for interfacial ion migrations. In addition, Ti3C2TX passivates the interface defects via its functional groups and establishes ballistic pathways for electrons with high chances of non-radiative recombination. Thus, 25.19% (certified as 24.41%) of efficiency with superior long-term operational stability is achieved.