Precise control over the isomorphic self-assembly of nanocluster superstructures via weak interactions remains a fundamental challenge in materials science, primarily due to the lack of directional guidance. Inspired by the ancient mortise-and-tenon joint, we herein report a series of crystalline nanocluster superstructures (MTC-1 and MTC-2) that were exclusively assembled by such molecular joints, representing the first paradigm of its kind. Despite alterations in functional groups (methyl and ethyl), the supramolecular packing motif remains invariant, underscoring the robustness of this directed assembly strategy. Notably, the ethyl groups in MTC-2 serve as “locking pins”, resulting in MTC-2 a fascinating Luban lock-like construction. This ingenious design endows MTC-2 with enhanced photogenerated charge migration and superior O₂ adsorption capability, achieving a record-high photocatalytic H₂O₂ production rate (19,978 μmol·g⁻¹·h⁻¹) among all isolated crystalline cluster-based materials, an order-of-magnitude enhancement over existing benchmarks. This work not only presents a record-breaking photocatalyst but also establishes a general assembly strategy, the mortise-and-tenon joint, which is expected to guide the rational design of functional superstructures across diverse nanocluster systems.

Grain boundaries (GBs) in perovskite polycrystalline films are the most sensitive place for the formation of the defect states and the accumulation of impurities. Thus, abundant works have been carried out to explore their properties and then try to solve the induced problems. Currently, two important issues remain. First, the role of GBs in charge carrier dynamics is unclear due to their component complexity/defect tolerance nature and the insufficiency in testing accuracy. Some works conclude that GBs are benign, while others consider GBs as carrier recombination centers. Things for sure are the deterioration in ion transport and perovskite decomposition. Second, to solve the known hazards of GBs, a lot of additives have been added to anchoring ions and passivate defects. But in most of those works, GBs and perovskite surfaces are treated in the same manner ignoring the fact that GB is essentially a homogeneous junction in a narrow and slender space, while surface is a heterogeneous junction with a stratified structure. In this review, we focus on works insight into GBs and additives for them. Additionally, we also discuss the prospects of the maturity of GB exploration toward upscaling the manufacture of perovskite photovoltaic and related optoelectronic devices.

Two novel anionic single-walled metal-organic nanotubes (MONTs), [(CH₃)₂NH₂][In(cdc)(thb)]·2DMF·9.5H₂O (FJU-105) and [(CH₃)₂NH₂][In(cdc)(H-btc)]·2DMA·11H₂O (FJU-106) (H₂cdc = 9H-carbazole-3,6-dicarboxylic acid, H₂thb = 2,5-thiophene dicarboxylic acid, H₃btc = 1,3,5-benzene tricarboxylic acid), are achieved by employing [In₆(cdc)₆]⁶⁺ metalloring cluster with largest diameter as the secondary building blocks (SBUs). The inner surface of FJU-106 is functionalized by uncoordinated -COOH groups of the H-btc linkers, leading to a higher proton conduction than FJU-105. At 70 °C, FJU-106 displays the proton conduction performances among MONTs, up to 1.80 × 10^-2 S·cm^-1. And FJU-105 and FJU-106 are the first examples of MONT proton conductors operating at subzero temperature.