The flexibility in structural design of organic semiconductors endows organic solar cells (OSCs) not only great function-tunabilities, but also high potential toward practical application. In this work, simple non-fused-ring electron acceptors are developed through two-step synthesis from single aromatic units for constructing efficient OSCs. With the assistance of non-covalent interactions, these rotatable non-fused acceptors (in solution) allow transiting into planar and stackable conformation in condensed solid, promoting acceptors not only feasible solution-processability, but also excellent film characteristics. As results, decent power conversion efficiencies of 10.27% and 13.97% can be achieved in single and tandem OSCs consisting of simple solution-cast blends, in which the fully unfused acceptors exhibit exceptionally low synthetic complexity index. In addition, the unfused acceptor and its based OSCs exhibit promising stabilities under continuous illumination. Overall, this work reveals valuable insights on the structural design of simple and effective electron acceptors with great practical perspectives.

Despite the remarkable performance progress being made, environmental concerns remain for lead halide perovskite solar cells (PSCs) because of the possible water dissolution of lead ions (Pb2+) into the environment. Herein, we succeed in mitigating Pb leakage of PSCs, for the first time, via implanting in situ polymerized networks into perovskites. We strategically transform the dormant monomer additives into chelating polymer networks within perovskite layers, which not only passivate the defects of perovskite but also protect Pb2+ from water dissolution. The resultant perovskite–polymer hybrids have successfully enabled state-of-art power conversion efficiencies (PCEs) for inverted PSCs (PCE of 22.1%) and large-area modules (PCE of 15.7%). More importantly, up to 94% rejection rate of Pb2+ dissolution is achieved upon directly immersing the unencapsulated devices into water, which reasonably simulates the exposure of the broken and unprotected panels to torrential rain for 24 h.

Metal−organic frameworks (MOFs) are porous crystalline materials with promising applications in molecular adsorption, separation, and catalysis. It has been discovered recently that structural defects introduced unintentionally or by design could have a significant impact on their properties. However, the exact chemical composition and structural evolution under different conditions at the defects are still under debate. In this study, we performed multidimensional solid-state nuclear magnetic resonance (SSNMR) coupled with computer simulations to elucidate an important scenario of MOF defects, uncovering the dynamic interplay between residual acetate and water. Acetate, as a defect modulator, and water, as a byproduct, are prevalent defect-associated species, which are among the key factors determining the reactivity and stability of defects. We discovered that acetate molecules coordinate to a single metal site monodentately and pair with water at the neighboring position. The acetates are highly flexible, which undergo fast libration as well as a slow kinetic exchange with water through dynamic hydrogen bonds. The dynamic processes under variable temperatures and different hydration levels have been quantitatively analyzed across a broad time scale from microseconds to seconds. The integration of SSNMR and computer simulations allows a precision probe into defective MOF structures with intrinsic dynamics and disorder.

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The defects in metal-organic frameworks (MOFs) can dramatically alter their pore structure and chemical properties. However, it has been a great challenge to characterize the molecular structure of defects, especially when the defects are distributed irregularly in the lattice. In this work, we applied a characterization strategy based on solid-state nuclear magnetic resonance (NMR) to assess the chemistry of defects. This strategy takes advantage of the coordination-sensitive phosphorus probe molecules, e.g., trimethylphosphine (TMP) and trimethylphosphine oxide (TMPO), that can distinguish the subtle differences in the acidity of defects. A variety of local chemical environments have been identified in defective and ideal MOF lattices. The geometric dimension of defects can also be evaluated by using the homologs of probe molecules with different sizes. In addition, our method provides a reliable way to quantify the density of defect sites, which comes together with the molecular details of local pore environments. The comprehensive solid-state NMR strategy can be of great value for a better understanding of MOF structures and for guiding the design of MOFs with desired catalytic or adsorption properties.

Understanding of drug-carrier interactions is essential for the design and application of metal-organic framework (MOF)-based drug-delivery systems,a nd such drug-carrier interactions can be fundamentally different for MOFs with or without defects.Herein, we reveal that the defects in MOFs play ak ey role in the loading of many pharmaceuticals with phosphate or phosphonate groups.T he host-guest interaction is dominated by the Coulombic attraction between phosphate/ phosphonate groups and defect sites,a nd it strongly enhances the loading capacity.F or similar molecules without ap hosphate/phosphonate group or for MOFs without defects,t he loading capacity is greatly reduced. We employed solid-state NMR spectroscopyand molecular simulations to elucidate the drug-carrier interaction mechanisms.T hrough as ynergistic combination of experimental and theoretical analyses,t he docking conformations of pharmaceuticals at the defects were revealed.

Understanding of drug-carrier interactions is essential for the design and application of metal-organic framework (MOF)-based drug-delivery systems,a nd such drug-carrier interactions can be fundamentally different for MOFs with or without defects.Herein, we reveal that the defects in MOFs play ak ey role in the loading of many pharmaceuticals with phosphate or phosphonate groups.T he host-guest interaction is dominated by the Coulombic attraction between phosphate/ phosphonate groups and defect sites,a nd it strongly enhances the loading capacity.F or similar molecules without ap hosphate/phosphonate group or for MOFs without defects,t he loading capacity is greatly reduced. We employed solid-state NMR spectroscopyand molecular simulations to elucidate the drug-carrier interaction mechanisms.T hrough as ynergistic combination of experimental and theoretical analyses,t he docking conformations of pharmaceuticals at the defects were revealed.

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