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Directional defects management in polycrystalline perovskite film with inorganic passivator is highly demanded while yet realized for fabricating efficient and stable perovskite solar cells (PSCs). Here, we develop a directional passivation strategy employing a two‐dimensional (2D) material, Cu‐(4‐mercaptophenol) (Cu‐HBT), as a passivator precursor. Cu‐HBT combines the merits of the targeted modification from organic passivator and excellent stability offered by inorganic passivator. Featuring with dense organic functional motifs on its surfaces, Cu‐HBT has the capability to "find" and fasten to the Pb defect sites in perovskites through coordination interactions during a spin‐coating process. During subsequent annealing treatment, the organic functional motifs cleave from Cu‐HBT and convert in situ into p‐type semiconductors, Cu2S and PbS. The resultant Cu2S and PbS not only serve as stable inorganic passivators on the perovskite surface, significantly enhancing cell stability, but also facilitate efficient charge extraction and transport, resulting in an impressive efficiency of up to 23.5 %. This work contributes a new defect management strategy by directionally yielding the stable inorganic passivators for highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

The electronic conductivity (EC) of metal–organic frameworks (MOFs) is sensitive to strongly oxidizing guest molecules. Water is a relatively mild species, however, the effect of H2O on the EC of MOFs is rarely reported. We explored the effect of H2O on the EC in the MOFs (NH2)2‐MIL‐125 and its derivatives with experimental and theoretical investigations. Unexpectedly, a large EC increase of 107 on H2SO4@(NH2)2‐MIL‐125 by H2O was observed. Brønsted acid–base pairs formed with the −NH2 groups, and H2SO4 played an important role in promoting the charge transfer from H2O to the MOF. Based on H2SO4@(NH2)2‐MIL‐125, a high‐performance chemiresistive humidity sensor was developed with the highest sensitivity, broadest detection range, and lowest limit of detection amongst all reported sensing materials to date. This work not only demonstrated that H2O can remarkably influence the EC of MOFs, but it also revealed that post‐modification of the structure of MOFs could enhance the influence of the guest molecule on their EC to design high‐performance sensing materials. [ABSTRACT FROM AUTHOR]

Modifiable one-dimensional materials are extremely desired in various applications, especially in room-temperature (RT) chemiresistive gas sensing. New one-dimensional (1D) CdS-based metal chalcogenide nanowires with a surface fully covered amino group (denoted as Cd-ATP) were prepared by the coordination self-assembly method. Featuring densely covered organic functional motifs, Cd-ATP is able to selectively recognize H2S through hydrogen bonding interaction between the amino group and H2S. Cd-ATP exhibits high sensitivity, an ultra-low limit-of-detection (116.49 ppt) and fast response/recovery among all reported room temperature H2S sensing non-composite materials. This work provides inspiration for the design and preparation of novel surface fully functionalized 1D materials for various chemical applications. [ABSTRACT FROM AUTHOR]

Accurate fire warning is very important for people's life and property safety. The most commonly used fire alarm is based on the detection of a single factor of gases, smoke particles, or temperature, which easily causes false alarm due to complex environmental conditions. A facile multi‐factor route for fabricating an accurate analog fire alarm using a Pb5S2I6 nanowire mesh based on its photoelectric and gas‐sensing dual function is presented. The Pb5S2I6 nanowire mesh presents excellent photoelectric detection capabilities and is sensitive to ppm‐level NO2 at room temperature. Under the "two‐step verification" circuit of light and gas factors, the bimodal simulation fire alarm based on this Pb5S2I6 nanowire mesh can resist the interference of complex environmental factors and effectively reduce the false alarm rate. [ABSTRACT FROM AUTHOR]

Organic small molecule semiconductor (OSMS) microporous crystals with strong π–π interactions are rare but have great potential in applications requiring both excellent mass and charge transport. To obtain such a microporous structure, effective molecule design and control over the packing of the OSMS are necessary but still challenging. Herein, we report three meso-tetrakis (4-carboxyphenyl) porphyrin (TCPP) based porous OSMS materials, 1, 2 and 3, whose porosity and π–π interactions among TCPPs were modulated by varying the H-bonding linkage nodes. The relationship among the hydrogen bonding structure, packing mode and sensing performances has been carefully studied. With the largest overlap between porphyrin rings and strongest face-to-face π–π interactions in the prepared compound, 1 showed the best performances. Moreover, it also represents the first RT NO2 chemiresistive sensing material that simultaneously achieved an experimental limit of detection as low as 20 ppb and a time of recovery as short as 0.6 min. This work revealed the key role of H-bonding linkage node in constructing a microporous OSMS and provides a new type of high-performance rt chemiresistive gas sensing material. [ABSTRACT FROM AUTHOR]