Enhancing Stability in All-Vacuum-Evaporated Hybrid Perovskite Solar Cells via a Bipolar Host as a Hole-Transporting...

Growing an ultrathin hybrid organic-inorganic perovskite film while maintaining high efficiency and addressing photostability challenges for commercial devices remains a significant hurdle. In this study, we explore the incorporation of organometallic copper phthalocyanine (CuPc) and MS-OC (a previously published spiro-based interfacial material for perovskite solar cells (PSCs), featuring an ortho-oriented carbazole donor) as an addition to the hole-transporting layer (HTL) in all-vacuum-deposited Cs_0.06FA_0.94Pb(I_0.68Br_0.32)₃ PSCs. By innovatively introducing a 3 nm-thin MS-OC layer at the CuPc-perovskite interface, we achieve a deeper understanding of the crystallographic dynamics of perovskites, resulting in a uniform and pinhole-free film. We demonstrate that PSCs utilizing the CuPc HTL with an MS-OC interfacial layer in a p-i-n architecture achieve a power conversion efficiency (PCE) of up to 14.42%. Remarkably, the CuPc/MS-OC-based device exhibits outstanding long-term photostability, maintaining its initial PCE over 400 h (T₁₀₀ = 400 h) under continuous sunlight illumination. By configuring the device architecture as ITO/MoO₃/CuPc/MS-OC/perovskite/C₆₀/BCP/Ag, we find that the evaporated MS-OC thin films effectively reduce nonradiative losses, passivate the perovskite, and enhance device performance. Our findings indicate that the polarity of the underlying surface significantly influences perovskite nucleation, underscoring the potential to improve photostability by controlling interfacial imperfections.