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High performance perovskites solar cells by hybrid perovskites co-crystallized with poly(ethylene oxide)
摘要： Hybrid perovskite materials have emerged as attractive alternatives for cost-effective solar cells in the past ten years. However, achieving hysteresis-free, stable and efficient solution-processed perovskites solar cells has remained as a significant fundamental challenge. In this study, we report a strategy that utilizes poly(ethylene oxide) to sequester the counter ions in the perovskite lattices to suppress the formation of point defects, reduce the migration of ions/vacancy and to facilitate crystal growth in a more thermodynamically preferred orientation. Systematical investigations indicate that poly(ethylene oxide) indeed form hydrogen bonds with perovskite, which reduces the formation of kinetically-driven point defects, minimize charge carrier recombination and sharpen the density of states distribution. As a result, un-encapsulated solution-processed perovskite solar cells exhibit stabilized power conversion efficiency with hysteresis-free characteristics and significantly improved ambient shelf- and thermal-stability at relative high humidity, in comparison to the reference devices that exhibit unstable power conversion efficiency with dramatically higher hysteresis factor and poorer device lifetime. Our studies demonstrate that development of hybrid perovskite materials co-crystallized with polymers is an efficient approach towards high performance perovskite solar cells.
关键词： photocurrent hysteresis,hydrogen bonding,stability,poly(ethylene oxide),power conversion efficiency,hybrid perovskite
更新于2025-09-11 14:15:04
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Enhancement of molecular-level ordering of isoindigo based organic materials through deprotecting of cleavable carbamate groups with long alkyl chains
摘要： A new highly soluble isoindigo based organic material with both cleavable carbamate protecting groups bearing long alkyl chains and thiophene groups was successfully synthesized. The carbamate protecting groups were easily removed by solvent-vapor thermal annealing using a mixture of trifluoroacetic acid and chloroform. Deprotection of the NH functional groups in the isoindigo backbone in situ facilitated H-bonding that dramatically improved the strength of the intermolecular interactions. X-ray diffraction and high-voltage electron microscopy studies of the resulting organic material showed long-range ordered crystalline structure. High crystallinity due to enhanced π-π stacking and hydrogen bonding significantly improved the charge carrier mobility. The hole mobilities of isoindigo based organic material measured by SCLC method improved from 3.46 x 10^-6 cm^2 V^-1 s^-1 to 1.13 x 10^-3 cm^2 V^-1 s^-1 upon deprotection of the NH functional groups.
关键词： Isoindigo,Conjugated,Crystallinity,Hydrogen bonding,Protecting groups
更新于2025-09-11 14:15:04
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Hydrogen-Bonded Two-Component Ionic Crystals Showing Enhanced Long-Lived Room-Temperature Phosphorescence via TADF-Assisted F?rster Resonance Energy Transfer
摘要： Molecular room-temperature phosphorescent (RTP) materials with long-lived excited states have attracted widespread attention in the fields of optical imaging, displays, and sensors. However, accessing ultralong RTP systems remains challenging and examples are still limited to date. Herein, a thermally activated delayed fluorescence (TADF)-assisted energy transfer route for the enhancement of persistent luminescence with an RTP lifetime as high as 2 s, which is higher than that of most state-of-the-art RTP materials, is proposed. The energy transfer donor and acceptor species are based on the TADF and RTP molecules, which can be self-assembled into two-component ionic salts via hydrogen-bonding interactions. Both theoretical and experimental studies illustrate the occurrence of effective F?rster resonance energy transfer (FRET) between donor and acceptor molecules with an energy transfer efficiency as high as 76%. Moreover, the potential for application of the donor–acceptor cocrystallized materials toward information security and personal identification systems is demonstrated, benefitting from their varied afterglow lifetimes and easy recognition in the darkness. Therefore, the work described in this study not only provides a TADF-assisted FRET strategy toward the construction of ultralong RTP, but also yields hydrogen-bonding-assembled two-component molecular crystals for potential encryption and anti-counterfeiting applications.
关键词： thermally activated delayed fluorescence,energy transfer,cocrystallization,hydrogen bonding self-assembly,room-temperature phosphorescence
更新于2025-09-10 09:29:36
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Molecularly imprinted photonic hydrogel sensor for optical detection of L-histidine
摘要： A molecularly imprinted photonic hydrogel (MIPH) is described for the optical determination of L-histidine (L-His). The inverse opal structure of MIPH was obtained by placing silica particles (230 nm) in molecularly imprinted polymer on a glass slide. After being fully etched by hydrofluoric acid, this inverse opal structure brings about a high specific surface and plentiful binding sites for L-His. If L-His is absorbed by the modified MIPH, its average effective refraction coefficient is increased. This causes the Bragg diffraction peak to be red-shifted by about 34 nm as the concentration of L-His increases from 0 to 100 nM. Much smaller diffraction peak shifts are obtained for other amino acids. The detection limit of this method is 10 pM. The response time towards L-His is as short as 60 s. In addition, the sensor can be recovered by treatment with 0.1 M acetic acid/methanol. It was applied to the determination of L-His in drinks sample.
关键词： Inverse opal structure,St?ber method,Nanoporous materials,Photonic crystal array,UV curing,Bragg diffraction peak,Hydrogen bonding,Reflection spectrum
更新于2025-09-10 09:29:36
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Solvothermal syntheses, structures and fluorescent properties of six ZnII/CdII coordination polymers constructed from N-donor ligands and multidentate organic acid
摘要： Six new coordination polymers(CPs) {[Cd(L1)(CHDA)]·H2O}n (1), [Zn3(L1)2(1,2,4-BTC)2(H2O)4]n (2), [Zn(L2)(D-CAM)(H2O)]n (3), [Zn3(L2)(1,2,4-BTC)2(H2O)4]n (4), [Cd(L2)(1,3,5-HBTC)]n (5) and {[Zn(L2)(4,4′-BOA)]·H2O}n (6) (L1 = 3,6-bis(imidazol-1-yl)pyridazine, L2 = 3,6-bis(benzimidazol-1-yl)pyridazine, 1,4-H2CHDA = (1 S,4 S)-cyclohexane-1,4-dicarboxylic acid, D-CAM = (1 R,3 S)-1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid, 1,3,5-H3BTC = benzene-1,3,5-tricarboxylic acid, 4,4′-H2OBA = 4,4′-oxydibenzoic acid) were achieved by reactions of the corresponding metal salt with mixed organic ligands. Their structures were determined by single-crystal X-ray diffraction, IR spectra, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. They exhibit varied structures, complexes 4 and 5 are porous three-dimensional (3D) frameworks, while 2 and 3 are 3D supermolecule structure formed by hydrogen-bonding interactions, and 1 is a two-dimensional (2D) network and 6 is an infinite one-dimensional (1D) chain. In addition, the fluorescent emission, fluorescence lifetimes of L1, L2 and 1–6 have been investigated and discussed.
关键词： Fluorescence lifetimes,Hydrogen-bonding interactions,Coordination polymers (CPs),Polycarboxylate ligands
更新于2025-09-10 09:29:36
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H-bonding Effect of Oxyanions Enhanced Photocatalytic Degradation of Sulfonamides by g-C3N4 in Aqueous Solution
摘要： In this study, the effect of oxyanions on the photodegradation of sulfonamides by graphitic carbon nitride (g-C3N4) was investigated. The results showed that the presence of disilicate (DS) could substantially improve the photodegradation of sulfamethazine (SMZ) in g-C3N4 aqueous suspension. The primary mechanism for the enhancing effect of DS was hydrogen bonding (H-bonding) interaction. The hydroxyl groups (-OH) and bridging oxygen (Si-O-Si) of DS can form H-bonds with the amine groups of g-C3N4 particles and sulfonamides, therefore soluble DS can act as a bridge to enhance the transfer and adsorption of SMZ onto the surface of g-C3N4 particles. The presence of DS did not change the mechanism of photodegradation, but there was an optimal concentration for DS to achieve the strongest enhancing effect. H-bonding effect was also found for other oxyanions derived from weak acids, such as silicate, dihydrogen phosphate and borate ions, because the partial ionization of these oxyanions allowed the existence of hydroxyl groups to form H-bonds. The present study not only deepens our understanding of the interface process of the photodegradation of sulfonamides in g-C3N4 aqueous suspension, but also provides a potential method to enhance the photocatalytic degradation of antibiotics in wastewater streams.
关键词： Carbon nitride,Oxyanions,Photocatalysis,Hydrogen bonding,Sulfonamides
更新于2025-09-09 09:28:46
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Steady State and Time-Resolved Fluorescence Study of 7,8-Benzoquinoline: Reinvestigation of Excited State Protonation
摘要： Steady state and time resolved spectral properties of 7,8-benzoquinoline (7,8-BQ) have been reinvestigated in a series of organic solvents of different proticity, polarity and wide range of pH. The salient features of this work are the effect of hydrogen bonding in protonation reaction which is explored through its behaviour in water and strong hydrogen bond donating solvent (trifluoroethanol). Quantum yield and rates (radiative, non-radiative and excited state protonation) have been calculated and discussed. Irreversible diffusion controlled excited state proton transfer in water and faster excited state protonation in trifluoroethanol is observed.
关键词： 7,8-benzoquinoline (Benzo[h]quinoline),protonation,trifluoroethanol,solvent,pH,hydrogen bonding
更新于2025-09-04 15:30:14
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Molecular properties, crystal structure, Hirshfeld surface analysis and computational calculations of a new third order NLO organic crystal, 2-aminopyridinium benzilate
摘要： A third order nonlinear optically active (NLO) organic proton transfer compound was synthesized by the reaction between 2-aminopyridine and benzilic acid. Single crystals of the product, 2-aminopyridinium benzilate, (2-APB) were grown by slow evaporation technique and the structure of 2-APB was confirmed by single crystal X-ray diffraction. In the structural network, cations and anions are linked through N+-H…O- intermolecular hydrogen bonding interactions. Elemental analysis, thermal analysis, UV-Vis, FT-IR and 1H and 13C NMR spectroscopic analyses were carried out to assess the structure and chemical makeup of the 2-APB crystal. Computational studies that include optimization of molecular geometry, natural bond orbital (NBO), Mulliken atomic charge and HOMO-LUMO analyses were also performed using B3LYP method at 6-311+ G (d,p) level of theory to explore various intermolecular interactions especially hydrogen bonding. Hirshfeld surface analysis indicates that the contacts involving hydrogen such as H…H, C…H and O…H have greater influence on the molecular properties of 2-APB.
关键词： NBO analysis,Hydrogen bonding,DFT,Single crystal XRD,Hirshfeld surface analysis
更新于2025-09-04 15:30:14
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Dynamics of Molecules Physically Adsorbed onto Metal Oxide Nanoparticles: Similarities between Water and a Flexible Polymer
摘要： Water at interfaces is considered present and important within almost all physical processes. Interfacial water shows nonbulk properties, however, its structure/organization and dynamics are on a still open debate. In parallel to that, the interfacial polymer in nanocomposites exhibits modi?ed structure and dynamics, the latter characteristic being widely considered responsible for the improved nanocomposite properties. One of the most suitable tools for studying dynamics of a variety of small molecules and macromolecules is broadband dielectric spectroscopy (BDS), mainly due to its high resolving power. BDS is employed here in combination with isothermal hydration and has proved quite illuminating in recording for the ?rst time striking similarities in the dynamics behavior between water molecules and ?exible polydimethylsiloxane macromolecules, when the latter molecules are individually adsorbed physically on the attractive surfaces of metal oxide nanoparticle. The qualitative similarities between water and polymer interfacial dynamics, for example, in their exhibiting time-scale and the elevation of the respective activation energy upon increasing of interfacial molecules fraction, lay most probably at the origins of the same main surface-adsorbed molecule interaction, i.e.. the hydrogen bonding. Whereas, the quantitative di?erences in molecular dynamics, e.g., slower, more energetically demanding, and cooperative interfacial dynamics for the polymer than for water, arise from the di?erent scale of the two molecular motions (<1 nm for water and ≥1 nm for the polymer) and/or from alternations in interfacial layer density.
关键词： dielectric spectroscopy,water,nanoparticles,polydimethylsiloxane,interfaces,dynamics,hydrogen bonding
更新于2025-09-04 15:30:14
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Target-switched triplex nanotweezer and synergic fluorophore translocation for highly selective melamine assay
摘要： This paper describes a triplex DNA nanotweezer to specifically capture melamine (MEL). The triplex-forming oligonucleotide (TFO) arm can be switched from the open state to the closed state once MEL binds to the abasic site (AP site) in duplex via the bifacial hydrogen bonding with thymines. Following this nanotweezer operation, the AP site-bound fluorophore is translocated to the terminal triplet to subsequently light up the nanotweezer. The TFO arm is found to be pivotal for permitting the AP site binding. The synergic processes of target competition and fluorophore translocation support a high selectivity for the MEL assay even against the inherent adenosine and the MEL hydrolysis products. Chelerythrine is employed as the fluorescent probe. The detection limit of MEL was estimated to be about 140 nM assuming a signal-to-noise ratio of 3. It was applied to the determination of MEL in spiked milk samples without any separation procedure. Conceivably, this method opens a new avenue towards highly selective triplex-based sensors by making use of other commercially available DNA modifications for recognizing other analytes.
关键词： Milk,Chelerythrine,Switch,Fluorescence,Hydrogen bonding,DNA,Fluorometry,Abasic site
更新于2025-09-04 15:30:14