NIR-II Organic Photothermal Cocrystals with Strong Charge Transfer Interaction for Flexible Wearable Heaters

The organic cocrystal strategy has provided a convenient and efficient platform for preparing organic photothermal materials.However,the rapidly directional preparation of cocrystals with desirable photothermal properties remains challenging due to a lack of suitable design ideas.Here,two new photothermal cocrystals,MTC and MFC,based on acceptor molecules(TCNQ and F4TCNQ)with different electron-withdrawing capacities were quickly prepared by the coprecipitation method,aiming to explore the effect of charge transfer(CT)interaction on photothermal properties.Compared with MTC,the stronger intermolecular CT interaction in MFC facilitates extending the absorption range(from the NIR-I to the NIR-II region)and enhancing the non-radiative transition process.Under the 808 nm laser irradiation,the photothermal conversion efficiency(PCE)of MFC is 54.6%,whereas MTC displays a mere 36.8%.The MFC cocrystal was further combined with a flexible polymer substrate(HPDMS)to prepare a flexible wearable heater(HPDMS@MFC),which exhibits excellent NIR-II photothermal performance.This work points out a research direction for the rapid assembly of efficient photothermal cocrystals and additionally provides an extensive application prospect for organic photothermal cocrystals in the field of wearable devices.

Covalent organic framework monolayer:Accurate syntheses and advanced application

Covalent organic framework(COF)monolayers,with atomically thin,ordered networks,and rich functionality,are widely studied due to their unusual structure/property relationships.However,synthesizing COF monolayer has remained an unmet challenge due to the difficulty of controlling reactions at the monolayer limit with large-scale uniformity.The identification and development of new reactions and polymerization conditions are critical for the further advancement of COF monolayer materials.Moreover,as one-molecule-thick a freestanding films,COF monolayer offers an ideal material system.Many advanced applications of COF monolayer have been explored in recent literature.This review provides an overview of the current state of precise synthetic strategies for COF monolayer,highlighting the advantages and limitations of different synthetic approaches and key challenges related to enhancing quality,and emphasizing the unique benefits of COF monolayer as both an ideal model system and for advanced applications.

Recent advances in the electrocatalytic oxidative upgrading of lignocellulosic biomass

Lignocellulosic biomass is a critical renewable carbon resource,but most of its utilization is inefficient,and elec-trocatalytic oxidation is a promising method of upgrading lignocellulose into value-added fuels and chemicals under mild operating conditions.Recently,efforts to enable conversion with a high efficiency and low energy con-sumption have been reported,but understanding the reaction mechanisms and realizing scaled-up applications of the electrooxidation of lignocellulosic biomass are still in their early stages.A timely overview of recently reported general reaction mechanisms,particularly the strategies developed for use in improving the reaction efficiencies,is necessary to inspire research regarding the highly efficient utilization of lignocellulose.Herein,we summa-rize the strategies developed to improve electrocatalytic performance in oxidative lignocellulose conversion.The organized summary includes strategies ranging from designing efficient electrocatalysts and adding functional co-catalysts or electrolytes to employing advanced electrolyzers.A comprehensive overview of representative examples should provide universal principles to yield insight into the reaction processes and guide the design of efficient electrocatalytic systems.Finally,the challenges and opportunities in developing the electrocatalytic oxidative upgrading of lignocellulosic biomass in the near future are proposed.

基于基态和激发态之间跃迁过程的DBTTF-TCNB共晶的光热转换机制

有机共晶,由于其光热转换性质,为光热成像、生物应用和海水淡化等诸多领域带来了希望和活力.然而,有机共晶的光热转换机制尤其缺少详细且深入的理论研究.本研究使用含时密度泛函理论方法探索了激发和去激发过程,并解释了DBTTF-TCNB共晶比其组分单晶具有更高光热转换效率的原因.结果显示,高激发态的高占比促进了非辐射跃迁的发生.基于DBTTF-TCNB共晶中给电子基团和吸电子基团间的电荷转移结果,我们发现给体和受体之间吸引电子的竞争可能会促进光热转换,且给电子基团在共晶结构中也十分重要.这些结果可为光热转换共晶的设计提供理论指导.轨道贡献和电子密度差进一步证明了我们的结论.因此,本研究从量子化学的角度给光热共晶在创新领域的应用提供了理论依据.

Polymer: Non-fullerene acceptor heterojunction-based phototransistor for short-wave infrared photodetection

It remains full of challenge for extending short-wave infrared(SWIR)spectral response and weak-light detection in the context of broad spectral responses for phototransistor.In this work,a novel poly(2,5-bis(4-hexyldodecyl)-2,5-dihydro-3,6-di-2-thienyl-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thiophene)(PDPPT3-HDO):COTIC-4F organic bulk-heterojunction is prepared as active layer for bulk heterojunction phototransistors.PDPPT3-HDO serves as a hole transport material,while COTIC-4F enhances the absorption of SWIR light to 1020 nm.As a result,smooth and connected PDPPT3-HDO film is fabricated by blade coating method and exhibits high hole mobility up to 2.34 cm^(2)·V^(-1)·s^(-1) with a current on/off ratio of 4.72×10^(5) in organic thin film transistors.PDPPT3-HDO:COTIC-4F heterojunction phototransistors exhibit high responsivity of 2680 A·W^(-1) to 900 nm and 815 A·W^(-1) to 1020 nm,with fast response time(rise time~20 ms and fall time~100 ms).The photosensitivity of the heterojunction phototransistor improves as the mass ratio of non-fullerene acceptors increases,resulting in an approximately two orders of magnitude enhancement compared to the bare polymer phototransistor.Importantly,the phototransistor exhibits decent responsivity even under ultra-weak light power of 43μW·cm^(-2) to 1020 nm.This work represents a highly effective and general strategy for fabricating efficient and sensitive SWIR light photodetectors.

通过应变工程提高有机半导体的迁移率

有机半导体(OSCs)是推动柔性电子发展的关键.然而,其应用一直受到其较低迁移率的阻碍.虽然分子工程和器件工程可以提高OSC迁移率,但近年来进展几乎停滞不前.本研究揭示了有机半导体在应变下的层数依赖电荷输运特性,并通过应变工程可大幅提高其迁移率.施加应变可以减小分子间π-π间距并减少电子-声子散射,从而提高电荷输运效率.我们观察到应变因子和材料厚度之间存在直接相关性,较薄的晶体具有较高的应变因子.使用分子级薄的二维分子晶体,我们观察到迁移率显著提高了58%.我们的研究结果为提高有机半导体的迁移率开辟了新的途径.

Molecular Interactions in Atomically Precise Metal Nanoclusters

For nanochemistry, precise manipulation of nanoscalestructures and the accompanying chemical properties atatomic precision is one of the greatest challenges today. Thescientific community strives to develop and design customizednanomaterials, while molecular interactions often serve as key toolsor probes for this atomically precise undertaking. In thisPerspective, metal nanoclusters, especially gold nanoclusters,serve as a good platform for understanding such nanoscaleinteractions. These nanoclusters often have a core size of about 2nm, a defined number of core metal atoms, and protecting ligandswith known crystal structure. The atomically precise structure ofmetal nanoclusters allows us to discuss how the molecularinteractions facilitate the systematic modification and functionalization of nanoclusters from their inner core, through the ligandshell, to the external assembly. Interestingly, the atomic packing structure of the nanocluster core can be affected by forces on thesurface. After discussing the core structure, we examine various atomic-level strategies to enhance their photoluminescent quantumyield and improve nanoclusters’ catalytic performance. Beyond the single cluster level, various attractive or repulsive molecularinteractions have been employed to engineer the self-assembly behavior and thus packing morphology of metal nanoclusters. Themethodological and fundamental insights systemized in this review should be useful for customizing the cluster structure andassembly patterns at the atomic level.