Fangwen Cheng

Perovskite photovoltaics are limited by structural instabilities initiated during crystallization and amplified under operation. We report that a lattice-matched Prussian blue scaffold directs heterogeneous nucleation to produce highly oriented, strain-relaxed films. Its redox-active Fe–C≡N–Fe network mediates the conversion of Pb ⁰ and I ⁰ defects, and its rigid open framework suppresses A-site cation redistribution and the resulting electronic inhomogeneity under bias. This strategy yielded champion power conversion efficiencies of 26.1% (n-i-p) and 26.9% (p-i-n; 26.2% certified), scaling to 23.4% in 6-centimeter–by–6-centimeter minimodules and a certified 22.9% in 30-centimeter–by–30-centimeter submodules. Submodules with initial power conversion efficiencies ranging from 20.2 to 21.0% showed robust durability under accelerated aging and no discernible decline relative to a silicon reference over 5 months of outdoor testing.

Ultraviolet (UV) radiation poses a substantial challenge to the stability of prevalent p-i-n (positive-intrinsic-negative) perovskite solar cells (PSCs), demanding more robust hole-transport layers (HTLs) due to light incident from the HTL side. Here, we unveil that commonly used self-assembled monolayer (SAM)–type HTLs suffer from poor UV stability that causes irreversible damage to hole extraction and impairs device stability. To address this issue, we develop a polymeric and UV-stable HTL named Poly-2PACz, which exhibits strong binding to substrates and exceptional UV resistance over SAM-type HTLs. The PSCs blade-coated under ambient conditions using Poly-2PACz HTL achieved a remarkable efficiency of 26.0% and outstanding UV stability. Our cells retain 80% of the initial PCE even after about 500 hours of high-intensity UV illumination [7.7 times higher than that of air mass 1.5 global (AM 1.5G) solar spectrum]. Furthermore, Poly-2PACz exhibits good wettability and high conductance, enabling the fabrication of blade-coated minimodules with an aperture efficiency of 22.2% and excellent uniformity.

Crown ether effectively stabilizes the cubic phase of CsPbI₃ to inhibit the moisture invasion and phase transformation of CsPbI₃ films, producing large-area devices and improving device performance.

N-Methyl-2-pyrrolidone (NMP), forming only one PbI₂·NMP complex, is demonstrated as an excellent coordinative solvent for the fabrication of high-quality perovskite thin films.