查看更多>>摘要：In organic solar cells, fluorination has a great influence on the performance of non-fullerene acceptors, however there are very few studies on the effects of fluorination position on polymerized small molecule acceptors. In this article, two polymer acceptor materials (PAL1 and PAL2) with different fluorine substitution positions are investigated to study the influence of fluorinated forms on polymerized small molecule acceptor materials and the all-polymer solar cell performance. The end group fluorinated polymer acceptor material PAL1 and the pi-bridge fluorinated polymer acceptor material PAL2 have similar absorption spectra and energy levels. While the blend film based on the polymer donor PM6:PAL1 has smaller roughness, finer phase separation, and tighter molecular packing, compared to the blend film of PM6:PAL2. Thus PM6:PAL1-based all-polymer organic solar cells (all-PSCs) have longer carrier life, faster carrier mobilities, and less bimolecular recombination.These polymer properties can simultaneously enhance the Jsc and FF of PM6:PAL1 based devices, finally achieving a device efficiency of 13.53%, which is significantly better than PM6:PAL2 based devices (9.16%). More importantly, the device based on PM6:PAL1 has excellent stability. When stored in a nitrogen atmosphere for 90 days, the PCE attenuation is only 4.2%. This work enriches the types of polymer acceptor materials and provides new ideas for the design of high-performance all-PSCs.
查看更多>>摘要：Nucleolus selective imaging can reveal the nucleolus structure and characters of cells in different states, and is considered critical in early disease diagnosis and treatment, and in designing targeted delivery systems. In this paper, we analyzed the factors affecting the nucleolus targeting properties of carbon dots by preparing a variety of carbon dots. Only carbon dots with m-phenylenediamine as the carbon source can specifically target the nucleolus. Meanwhile, the nitrogen content in the carbon dots also affects their targeting properties to the nucleolus. The molar ratio of m-phenylenediamine (carbon source) to L-aspartic acid (nitrogen source) was changed to control the nitrogen content in the carbon dots, and the carbon dots had the best nucleolus targeting and imaging effect when the molar ratio was 1:0.5 (carbon: nitrogen). Additionally, binding of carbon dots to RNA in the nucleolus has been demonstrated by digestion experiments, and their cellular internalization is temperature, ATP, and micropinocytosis dependent. Our results provide ideas and methods for the design of nucleolus-targeted carbon dots.
查看更多>>摘要：As a class of typical metal complexes, luminescent Ru(II) complexes with diamine ligands have drawn much research attention for the application of optoelectronic functional field. The previous reports focused mainly on mononuclear Ru(II) complexes, and there had been little research on the comparison between mononuclear and binuclear Ru(II) complexes. In this work, a series of diamine ligands with bidentate and multiple dentate chelating sites were synthesized. Their Ru(II) complexes were synthesized and discussed in detail so that a direct comparison between mononuclear and binuclear Ru(II) complexes could be performed, including single crystals and electronic structure. To eliminate the effect of inhomogeneous microenvironment on sensing performance, these Ru(II) complexes were doped into a polymer matrix via electronspinning method. The sensing performance of mononuclear Ru(II) complexes was compared with that of binuclear Ru(II) complexes. It was concluded that binuclear Ru(II) complexes were superior to mononuclear Ru(II) complexes in sensitivity, response/sensitive performance and photostability. This was because there was more MLCT (metal-to-ligand-charge-transfer) contribution in a binuclear Ru(II) complex which was more O-2 quenchable than LLCT (ligand-to-ligand-chargetransfer). There were two emissive/sensitive centers in a binuclear Ru(II) complex, offering more collision chances with O-2 molecules and leading to fast response and recovery behavior, as well as improved photo stability. The major advantage of this work was the observation of linear sensing response, which was rather rare for Ru(II)-based probes.
查看更多>>摘要：Bisarylic methanone pi-architecture PTZ-BZ-DBT with carbonyl group as the acceptor and phenothiazine as the donor was synthesized. Theoretical calculations and photophysical properties in solution demonstrated that the obtained donor-acceptor (D-A) type molecule PTZ-BZ-DBT adopts a molecular conformation of high distortion and significant intramolecular charge transfer (ICT) behavior, which endows it not only with intense solid-state luminescence but also with a high-contrast mechanofluorochromic (MFC) feature. The original as-prepared samples of PTZ-BZ-DBT display bright yellow-green fluorescence. When the as-prepared samples are ground, the ground solid powders exhibit orange-red fluorescence are obtained. Accordingly, during the grinding process, the emission wavelength of the solid powders red shifts from 518 nm of the as-prepared samples to 617 nm of the ground samples, and thus a spectral shift of 99 nm is observed. Different from general MFC materials, if the ground solid powders are fumed by DCM vapor or annealed at 150 degrees C, the fluorescence peaks blue shift to about 564 nm, and the yellow-emitting Y-powders are gained. However, the ground samples can be converted into the as-prepared solid powders through solvent recrystallization; thus tri-color switching is obtained. The PXRD, fluorescence lifetimes, DSC and the spectral analysis demonstrate that the remarkable MFC nature of PTZ-BZDBT is attributed to crystalline-to-amorphous transition. Further, the red shift of the fluorescence band after grinding can be ascribed to the extension of conjugate length and subsequent planar intramolecular charge transfer (PICT) induced by conformational planarization under external forces.
查看更多>>摘要：Thiobases or sulfur-substituted nucleobases have been developed and recognized as prospective class of heavy-atom-free photosensitizer for photodynamic therapy due to their appealing phototherapeutic properties. In this work, we have prepared the thionated BODIPY analogues by replacing oxygen with sulfur atom at exocyclic carbonyl group, which display red-shifted absorption band, remarkable fluorescence quenching and high singlet oxygen quantum yield as well as excellent photostability. Sulfur substitution stabilizes the LUMO level and destabilized the HOMO, and thus reduces the energy gap and shift the absorption to long wavelength. The replacement of O by S-atom is essential for the enhancement of the intersystem crossing from the singlet excited state to the reactive triplet state. DFT calculations revealed that large spin-orbit coupling (SOC) could be responsible for the efficient population of the triplet state. In addition, the thionated BODIPY efficiently gen-erates the intracellular reactive oxygen species (ROS) with low cytotoxicity. These studies demonstrate that the thionated BODIPY analogue is potentially suitable for use as a photosensitizer.
查看更多>>摘要：Dopant-free, electron donor (D)-acceptor (A) type, polymeric hole-transporting materials (HTMs) possess excellent film formability and hole transport properties, which ensure high efficiency, stability, and reproducibility to the PVSCs. Compared with benzothiadiazole (BT), benzotriazole (BTA) was less incorporated into polymeric HTMs. Herein, two indacenodithieno[3,2-b]thiophene (IDTT)-BTA copolymers BT-T and BT-TT containing different pi -bridge of thiophene and thienothiophene, are synthesized and studied. BT-T bearing thiophene pi -bridge presents decent coplanarity, higher hole mobility, and better interface morphology than its sister polymer BT-TT. The PVSC with dopant-free BT-T displayed a peak power conversion efficiency (PCE) of 17.1% and remained above 85% of its initial PCE for more than 30 days at ambient conditions. In view of the rare report on the BTA-based polymeric HTMs, this work will cast lights on further exploration of high-efficiency D-A polymeric HTMs.
查看更多>>摘要：Charge transporting materials mainly including hole-transporting and electron-transporting materials, have played a vital role in charge separation, charge transfer, or charge-blocking in perovskite solar cells (PSCs). Among them, some specific species also possess other functions, such as inducing high-quality perovskite-crystalline formation, passivating defects of perovskite, preventing perovskite from erosion of moist, ultraviolet light or heat, as well as modifying electrodes. These bi-or multi-functional charge transporting materials have effectively improved the performance of PSCs in both efficiencies and stability, therefore it is necessary to summarize and analyze the characteristics of these materials as reference for associated researchers. In this review, we will introduce such materials from two aspects of hole-transporting and electron-transporting materials, which were further classified according to the feature of functions. Finally, future opportunities and challenges of exploration of these types of materials are proposed from the perspective of promoting the practical application of PSCs.
查看更多>>摘要：The evaluation of the HSO3- levels in the biological systems and food samples is of great significance in the understanding its physiological/pathological roles and realizing food security supervision. In this work, a near infrared (NIR) emitted fluorescence probe (QNP) has been successfully developed to detect HSO3- in live animals and food samples. QNP was designed with a large pi-conjugation structure by conjugating of quinolinium with 3H-naphtho[2,1-b]pyran moiety through a reactive C=C double bond. Spectroscopic titration, high resolution mass spectrometry (HR MS), 1H NMR titration and theoretical computation indicates that HSO3- attacks to the C=C double bond through an established 1,4-nucleophilic addition reaction leads to the interruption of the pi-conjugation system of QNP, resulting in dramatic decline of the UV-vis absorption and fluorescence spectra. QNP was featured with near infrared emission (centered at 690 nm), high water-solubility (98% water), large Stokes shift (218 nm), perfect selectivity, fast response time (within 50 s) to HSO3- , reliability in broad pH range (6.5-11.5) and low cytotoxicity. The application of QNP in biological systems has been demonstrated by the monitoring of exogenous HSO3- in live adult zebrafish and nude mouse. Furthermore, the evaluation of HSO3- level in several food samples including sugar, white wine, canned fruits and jasmine tea drinks were also determined by fluorescence colorimetric method using QNP.
查看更多>>摘要：Multi-color emission materials with unique molecular stackings in aggregated states have attracted great attention. To better understand the relationship between emission properties and co-assembling systems, we report herein a novel aza-borondiquinomethene complex (TAB) bearing tetraphenylethene substituents at the 4,4 '-positions of its central core. This system was found to crystallize in two polymorphs with different molecular stackings. TAB (G) exhibits weak green emission (lambda(em) = 500 nm, empty set = 6.0%) due to a strong pi-pi interaction, whereas TAB (Y) exhibits a much brighter yellow emission (lambda(em) = 550 nm, empty set = 52.0%). The different molecular stackings gave rise to the interesting emissions, and these unusual emission phenomena were rationalized by Hirshfeld surface analyses and theoretical calculations. This research may broaden the scope for the design of multi-color emission materials adopting different aggregation states.
查看更多>>摘要：Because silver (Ag) nanoprisms with sharp edges are inherently unstable, it is very important to develop a facile method that can dramatically improve the chemical stability of Ag nanoprisms while maintaining their inherent properties, including their plasmonic properties. In the present work, we developed a novel surface passivation method based on a single-step water-based process and showed that it significantly improved the chemical stability of Ag nanoprisms. Specifically, tetramethylethylenediamine (TMEDA) was used as an organic capping ligand, and the TMEDA-treated Ag nanoprisms retained their triangular shape even when exposed to various strong etchants including bromide, chloride, and hydrogen peroxide. Only in the presence of iodide did the sharp corners of the nanoprisms become spontaneously etched, and this etching resulted in a dramatic change in their localized surface plasmon resonance (LSPR) properties. The extent of the change of the LSPR properties depended on the concentration of iodide; hence, aqueous solutions of the TMEDA-treated Ag nanoprisms with different concentrations of iodide showed different colors. Based on this relationship, a colorimetric sensing probe that can detect iodide in aqueous solutions was developed. The sensing probe exhibited very high selectivity for iodide and the ability to determine the concentration of iodide over a wide range of concentrations. In addition, the probe was found to provide significant advantages over previously developed systems for iodide analysis, including portability, ease of use, point-of-care analysis, and naked-eye detection.
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Elsevier