Zhifang Shi

All-perovskite tandem solar cells (TSCs) hold a substantial promise for achieving ultrahigh-efficiency photovoltaics beyond the Shockley-Queisser limit. However, their development has been hampered by challenges associated with a narrow-bandgap tin-lead (Sn-Pb) perovskite subcell. A key issue is inhomogeneous Sn/Pb distribution during crystallization, which generates trap states and accelerates degradation. Here, we introduce a molecular stabilization strategy by using S -allyl- l -cysteine (SALC) as a ligand that preferentially coordinates with tin(II) iodide (SnI ₂ ), thereby modulating crystallization kinetics. The strong thioether coordination leads to spatially uniform Sn/Pb distribution, and 3.5-fold reduction in Sn(IV) content due to the reduction capability of functional groups in SALC. Consequently, the resulting Sn-Pb perovskite solar cells achieve a champion power conversion efficiency (PCE) of 22.99% with an exceptional open-circuit voltage of 0.892 V. When integrated into all-perovskite TSCs, a certified PCE of 28.84% (29.44% laboratory-measured) is achieved along with a great improvement in operational stability compared to control devices, retaining nearly 90% of initial PCE after 420 hours of the maximum power point tracking under 1 sun illumination in ambient air.

The rapid improvement in the power conversion efficiency of perovskite solar cells has established them as a promising alternative to conventional photovoltaic technologies. Owing to their strong light absorption, tunable bandgap, solution processability, and lightweight nature, perovskite solar cells are particularly well suited for building‐integrated photovoltaic applications. This review summarizes the potential of perovskite solar cells for building‐integrated photovoltaic integration, with a focus on their implementation in semi‐transparent windows, colored facades, and flexible substrates. By enabling on‐site energy generation while preserving aesthetic and design flexibility, perovskite photovoltaics offer unique opportunities for urban energy systems. Finally, future research directions are outlined, focusing on materials and interface engineering, encapsulation strategies, and large‐area fabrication, which are essential for the practical deployment of perovskite solar cell–based building‐integrated photovoltaics in sustainable buildings.

The benign defect nature of iodide perovskites has gained strong momentum in understanding and application in perovskite devices; however, the understanding of defects in bromide perovskites remains elusive. Here we demonstrate that the biasing of lead bromide perovskite crystals, which has been broadly deemed as detrimental to device performance, can efficiently repair bulk point defects in them. The biasing results in a significant bromide-vacancy reduction, starting from the cathode side and progressing to the anode side across the whole crystal. The vacancies can diffuse back after several weeks of storage. By introducing bromine in crystal growth, we permanently reduce the bromide-vacancy concentration by ~1,000 times, enhancing charge transport and stability in formamidinium lead bromide crystals. The optimized formamidinium lead bromide detector exhibited a very high detection performance including an energy resolution of 0.7% under ¹³⁷Cs 662-keV γ-rays measured under room-temperature, high-performance iodine K-edge X-ray detection at low agent concentrations and dramatically improved radiation hardness.

The light-emitting diodes (LEDs) used in indoor testing of perovskite solar cells do not expose them to the levels of ultraviolet (UV) radiation that they would receive in actual outdoor use. We report degradation mechanisms of p-i-n–structured perovskite solar cells under unfiltered sunlight and with LEDs. Weak chemical bonding between perovskites and polymer hole-transporting materials (HTMs) and transparent conducting oxides (TCOs) dominate the accelerated A-site cation migration, rather than direct degradation of HTMs. An aromatic phosphonic acid, [2-(9-ethyl-9H-carbazol-3-yl)ethyl]phosphonic acid (EtCz3EPA), enhanced bonding at the perovskite/HTM/TCO region with a phosphonic acid group bonded to TCOs and a nitrogen group interacting with lead in perovskites. A hybrid HTM of EtCz3EPA with strong hole-extraction polymers retained high efficiency and improved the UV stability of perovskite devices, and a champion perovskite minimodule—independently measured by the Perovskite PV Accelerator for Commercializing Technologies (PACT) center—retained operational efficiency of >16% after 29 weeks of outdoor testing.