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 degrees C, 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. P-xylylenediphosphonic acid (p-XPA) was introduced between the hole transport layer (HTL) and the perovskite film. P-XPA made the HTL planar, promoted perovskite crystallization, and effectively passivated the bottom defects of the perovskite film. Ultimately, the device power conversion efficiency reached 25.87 % and the stability was significantly improved. image