Dion-Jacobson (DJ) hybrid perovskite (HP) single-crystal photodetectors often require operation under external bias due to the centrosymmetric structure of the material, which is not conducive to the intelligence and lightweight of the devices. To solve this problem, the key issue is how to regulate the noncovalent interaction between interlayer diammonium cations and inorganic frameworks to successfully induce polarity. However, there is a lack of research on the relationship between the configuration of diammonium cations and the structure symmetry of DJ HPs. Herein, we successfully constructed a series of polar DJ HPs (1,3-BMACH)PbX4 (X = Cl, Br, I; 1,3-BMACH is 1,3-bis(aminomethyl)cyclohexane) by changing the configuration of organic cations. It was found that the hydrogen bonding strength between 1,3-BMACH2+ cations and the bilateral inorganic framework is different, and it causes the inorganic layer to be more twisted, resulting in a deviation of the positive and negative charge centers in (1,3-BMACH)PbX4 (X = Cl, Br, I) and successfully inducing polarity. Subsequently, we achieved efficient self-powered X-ray detection in the single-crystal device of (1,3-BMACH)PbBr4 through polarity-induced bulk photovoltaic effect, which owns outstanding sensitivity (157.3 μC Gy–1 cm–2, 0 V bias) and stability under X-ray radiation. Studying the relationship between the configuration of diammonium cations and the crystal structure in DJ HPs can help us design more efficient self-powered optoelectronic devices.
Yuanchuan Ma,Jiao Wei,Yuquan Cai,Jieyuan Zheng,Carla Bittencourt,Hong Fan
Rough structures have gained increasing attention since they are essential for surfaces with special wettability , which can be used for various applications. It is still a challenge to find a low-cost and simple way to fabricate rough surfaces despite extensive efforts. Herein, we report a facile strategy to fabricate self-roughened surfaces based on polarity-induced phase separation. The strategy relies on the migration of flexible chains of the nonpolar polysiloxane to airside, driven by surface tension and polarity difference with the polar crosslinker, which forms a self-roughened surface with numerous protrusions. It is worth noting that this strategy does not require strict control of procedures, since it is insensitive to environmental changes unlike other phase separation methods, as shown by the results of systematic studies on several key parameters. Modified fabrics and coatings exhibit excellent superhydrophobicity with a water contact angle higher than 160°. Moreover, due to the strong hydrogen bonds formed by the polar urea groups of the crosslinker with substrates, the abrasion resistance of the coating is significantly enhanced. It is believed that the proposed novel and facile strategy will be a promising candidate for industrial manufacturing.
Yingying Zhang,Carice Chong,Wangshu Tong,Haitao Li,Hiang Kwee Lee,Jie Han
Polyvinylidene fluoride (PVDF) is promising for piezo-catalytic applications owing to its excellent biocompatibility, flexibility, and durability. However, it is limited by weak electroactivity originating from its intrinsically low β piezoelectric phase content (<20%) and insulating properties. Here, we achieve efficient piezo-catalysis by introducing a self-polarized PVDF-based composite containing carbon nanotube (CNT) as conductive fillers. Notably, our self-polarized CNT/PVDF (SCP) ensemble exhibits a high β phase content of ∼95%, which is up to 6-fold higher than the original PVDF powder, and superior electrical activity by exploiting the polarity induction effect of water molecules. As a proof-of-concept demonstration, the SCP realizes efficient degradation of organic-polluted water by at least 95% within 2 h of ultrasonication (240 W), even at high pollutant concentration (40 mgL −1 ). Systematic investigations unveil its excellent recyclability and adaptability to various tropical or subtropical natural waters. More importantly, the SCP also achieves efficient H 2 O 2 production of up to ∼13.5 mmol g CNT −1 h −1 , which is > 6-fold and > 19-fold better than standalone self-polarized PVDF (i.e., without CNT content) and emerging piezo-catalytic designs, respectively. This study offers a unique approach for designing PVDF-based piezo-catalyst to expedite mechanically-driven catalysis towards practical applications.
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