Enhancing Hole Transport Uniformity for Efficient Inverted Perovskite Solar Cells through Optimizing Buried Interface Contacts and Suppressing Interface Recombination

[4-(3,6-dimethyl-9H-carbazol-9yl)butyl]phosphonic acid (Me-4PACz) self-assembly material has been recognized as a highly effective approach for mitigating nickel oxide (NiOx) surface-related challenges in inverted perovskite solar cells (IPSCs). However, its uneven film generation and failure to effectively passivate the buried interface defects limit the device's performance improvement potential. Herein, p-xylylenediphosphonic acid (p-XPA) containing bilateral phosphate groups (-PO3H2) is introduced as an interface layer between the NiOx/Me-4PACz and the perovskite layer. P-XPA can flatten the surface of hole transport layer and optimize interface contact. Meanwhile, p-XPA achieves better energy level alignment and promotes interfacial hole transport. In addition, the bilateral -PO3H2 of p-XPA can chelate with Pb2+ and form hydrogen bond with FA+ (formamidinium cation), thereby suppressing buried interface non-radiative recombination loss. Consequently, the IPSC with p-XPA buried interface modification achieves champion power conversion efficiency of 25.87% (certified at 25.45%) at laboratory scale (0.0448 cm2). The encapsulated target device exhibits better operational stability. Even after 1100 hours of maximum power point tracking at 50 ℃, its efficiency remains at an impressive 82.7% of the initial efficiency. Molecules featuring bilateral passivation groups optimize interfacial contact and inhibit interfacial recombination, providing an effective approach to enhancing the stability and efficiency of devices.