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Pure FAPbI3‐based, with FA being formamidinium, perovskite solar cells (PSCs) have garnered worldwide recognition for their exceptional efficiency. However, the phase stability of FAPbI3 is still a big obstacle in this area, because the ordinary strategy using MA+, Br−, Cs+ to stabilize α‐FAPbI3 phase can cause the bandgap change and ion migration. Herein, a new strategy is introduced to improve the α‐FAPbI3 phase stability by using a self‐assembled bridging layer at the buried interface of FAPbI3 perovskite in the n–i–p solar cell structure. A series of multidentate bisphosphonic acid molecules are screened and demonstrate that etidronic acid (EA) with the smallest steric hindrance behaves the best. The four P‐OH groups can first form multidentate anchors on SnO2 while the remaining unanchored ─OH and P═O groups can form strong interaction between I− and Pb2+. Thus, a strong and stable bridging layer is formed, which greatly increases the energy barrier of phase transition of FAPbI3. As a result, the pure FAPbI3‐based (MA+, Br+, Cs+‐free system) n–i–p device reached an impressive power conversion efficiency of 24.2% with good stability. Furthermore, the strong interaction between EA and Pb2+ can greatly reduce lead leakage in harsh conditions. [ABSTRACT FROM AUTHOR]

As the power‐conversion efficiency (PCE) of organic–inorganic lead halide perovskite solar cells (PSCs) is approaching the theoretical maximum, the most crucial issue concerns long‐term ambient stability. Here, the application of PCN‐224 quantum dots (QDs) is reported, a typical Zr‐based porphyrinic metal–organic framework (MOF), to enhance the ambient stability of PSCs. PCN‐224 QDs with abundant Lewis‐base groups (e.g., CO, C−N, CN) contribute to high‐quality perovskite films with enlarged grain size and reduced defect density by interaction with under‐coordinated Pb2+. Meanwhile, PCN‐224 QDs enable the well‐matched energy level at the perovskite/hole transport layer (HTL) interface, thereby facilitating hole extraction and transport. More importantly, PCN‐224 QDs‐treated HTL can capture Li+ from bis(trifluoromethanesulfonyl)imide additive, leading to the reduced aggregation and less direct contact with moisture for hygroscopic Li‐TFSI. Moreover, PCN‐224 QDs mitigated Li+ ion migration into the perovskite layer, thus avoiding the formation of deleterious defects. The resultant devices yield a champion PCE of 22.51%, along with substantially improved durability, including humidity, thermal and light soaking stabilities. The findings provide a new approach toward efficient and stable PSCs by applying MOF QDs. [ABSTRACT FROM AUTHOR]

With the continuous research and development of amidoxime (AO)‐based adsorbents, industrialization production of uranium from seawater gradually becomes a reality. However, the currently available AO‐based adsorbents still suffer from low adsorption rate and poor selectivity. Herein, vertically aligned polyamioxime–graphene oxide (VA‐PG) sheet membrane is fabricated by directional freeze casting. The run‐through microchannels contribute to the free diffusion of uranyl ions (UO22+), leading to the fast adsorption kinetics. Furthermore, partially reduced graphene oxide allows high photothermal conversion efficiency and rapid in‐plane heat transfer, resulting in the fast temperature rise under simulated sunlight irradiation. Because of the endothermic behavior of UO22+, light‐irradiated VA‐PG can simultaneously satisfy the requirements of high adsorption capacity (13.63 mg‐U g‐Ads−1), high adsorption rate (0.43 mg g−1 day−1), and excellent selectivity toward U(VI) over V(V) (U/V = 1.24) in natural seawater, indicating the right direction for a breakthrough in the field of uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

Extraordinary electronic and photonic features (e.g., tunable direct bandgap, high ambipolar carrier mobility) render few‐layer black phosphorus (BP) nanosheets/quantum dots an important optoelectronic material. However, most of the BP applied in metal halide perovskite solar cells (PSCs) are produced by sonication‐assisted liquid exfoliation, which inevitably brings inferior electronic properties, thus leading to limited beneficial effects. Furthermore, this study uncovers that the intrinsic instability of BP nanosheets sandwiched between (CsFAMA)Pb(BrI)3 perovskite and spiro‐OMeTAD has a deleterious effect on the performance stabilization of PSCs. To address the above constraints, a feasible strategy herein is developed by introducing high‐quality fluorinated BP (F‐BP) nanosheets synthesized by one‐step electrochemical delamination. In addition to P‐Pb coordination, there is a strong hydrogen bond between F− and MA+/FA+ as well as an ionic bond between F− and Pb2+ for the perovskite/F‐BP interface, thus leading to fewer interfacial traps than perovskite/BP, which is responsible for the highest power conversion efficiency (22.06%) of F‐BP devices. More importantly, F‐BP devices exhibit significantly improved humidity and shelf‐life stabilities due to the excellent ambient stability of F‐BP, resulting from the antioxidation and antihydration behavior of fluorine adatoms. Overall, the findings provide a promising strategy to simultaneously enhance the photovoltaic performance and long‐term stability of BP‐based PSCs. [ABSTRACT FROM AUTHOR]

Passivation engineering has been identified as an effective strategy to eliminate the targeted interfacial defects for improving the efficiency and stability of perovskite solar cells (PSCs). Herein, 4-trifluorophenylammonium iodide (CF 3 PhAI) is presented as a multifunctional passivation agent to modify buried SnO 2 /perovskite and perovskite/hole transport layer (HTL) interfaces. Upon incorporation of CF 3 PhAI between SnO 2 and perovskite, CF 3 PhAI can chemically link to SnO 2 via Lewis coordination and electrostatic coupling, thereby effectively passivating under-coordinated Sn and filling the oxygen vacancy. Meanwhile, CF 3 PhAI helps anchor PbI 2 and organic cations (MA + /FA + ) to control the crystallization of the perovskite. Consequently, reduced interfacial defects, homogeneous perovskite crystallites, and better energetic alignment can be simultaneously achieved. When CF 3 PhAI was further used to modify the perovskite/HTL interface, the fabricated PSCs yielded an impressive power conversion efficiency of 23.06% together with negligible J - V hysteresis. The unencapsulated devices exhibited long-term stability in wet conditions (91.8% efficiency retention after 1000 h) due to the water-resistant CF 3 PhAI. We also achieved good light soaking stability, maintaining 86.1% of its initial efficiency after aging for 720 h. Overall, our finding provides a promising strategy for modifying the dual contact interfaces of PSCs toward improved efficiency and stability.