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Temperature sensitive properties of Eu2+/Eu3+ dual-emitting LaAlO3 phosphors
摘要： In this study, Eu2+/Eu3+ coexisting perovskite LaAlO3 phosphors were synthesized by a traditional high-temperature solid-phase reaction method and investigated via X-ray diffraction data, X-ray photoelectron spectroscopy and temperature-dependent photoluminescence spectra. The Eu2+/Eu3+ coexisting LaAlO3 phosphors exhibit excellent optical temperature sensing characteristics and are potential inorganic materials for temperature detection. The measured maximal absolute temperature sensitivity reaches 0.014 K-1, and the corresponding largest relative temperature sensitivity is 1.193% K-1, which are superior to most of previous reports of that. Meanwhile, the monitored signal peaks are well separated, providing a good signal discriminability. The energy level crossover relaxation of Eu2+ and Struck-Fonger crossover process involving O2–-Eu3+ charge transfer band were used to explain the different temperature-dependent responses of Eu2+ and Eu3+. This work may give new ideas for the future research of optical thermometric materials with high sensitivity and high discriminability.
关键词： Fluorescence intensity ratio,Charge transfer band,Thermometry phosphor,LaAlO3
更新于2025-11-14 15:13:28
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New copolymer involving PVK and F8BT for organic solar cells applications: Design, synthesis, characterization and theoretical studies
摘要： The new PVK-F8BT copolymer coupled to poly (9-vinylcarbazole) and poly(9,9-dioctyl?uorene-alt-benzothiadiazole) has been designed and elaborated by chemical oxidation for organic solar cells applications. Structural and photophysical properties were examined using di?erent and complementary techniques (Infrared, optical absorption, stationary and time resolved photoluminescence). The PVK-F8BT exhibited a broad absorption band covering the wavelength range from 200 nm to 700 nm covering the solar spectrum and, highlighting the charge transfer process. Moreover, the PVK-F8BT, showed a low band gap to be found to 1.9 eV and it average lifetime (2.62 ns) are longer than that of F8BT. The resulting copolymer exhibits original optical properties compared to the PVK and F8BT ones. The experimental analyses were coupled to theoretical calculations based on density functional theory and time-dependant density functional theory methods in order to better understand the structure-properties correlation. Furthermore DFT and TD-DFT calculations of the PVK-F8BT have been exploited to optimize the copolymer-based composites based on bulk heterojunction based organic photovoltaic copolymers with the 1-(3-methoxycarbonyl) propyl-1-phenyl-[6,6]–C61, as an acceptor. Thus, the band gap decreased to 1.69 eV, the power energy conversion e?ciency was about 7%. Our results have allowed us to discover a promising new photovoltaic material.
关键词： TD-DFT,Optical properties,Solar cells,Donor-acceptor,Charge transfer
更新于2025-10-22 19:40:53
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Regulating Charge-Transfer in Conjugated Microporous Polymer for Photocatalytic Hydrogen Evolution
摘要： Band gap engineering in donor-acceptor conjugated microporous polymers is a potential way to increase the solar energy harvesting towards photochemical water splitting. Herein, we report design and synthesis of a series of donor-acceptor CMPs [tetraphenylethylene (TPE) = donor and 9-fluorenone (F) = acceptor], F0.1CMP, F0.5CMP and F2.0CMP which exhibit tunable band gaps and photocatalytic hydrogen evolution from water. The donor-acceptor CMPs exhibit intramolecular charge transfer (ICT) absorption in the visible region (λmax=480 nm) and their band gap is finely tuned from 2.8 eV to 2.1 eV by increasing the 9-fluorenone content. Interestingly, they also show charge transfer emissions (in 540 -580 nm range), assisted by the energy transfer from the other TPE segments (not involved in CT interaction) as evidenced from fluorescence lifetime decay analysis. By increasing the 9-fluorenone content the emission color of the polymer is also tuned from green to red. Photocatalytic activities of the donor-acceptor CMPs (F0.1CMP, F0.5CMP and F2.0CMP) are greatly enhanced compared to the 9-fluorenone free polymer (F0.0CMP) which is essentially due to improved visible light absorption and low band gap of donor-acceptor CMPs. Among all the polymers F0.5CMP with an optimum band gap (2.3 eV) shows highest H2 evolution under visible light irradiation. Moreover, all the polymers show excellent dispersibility in organic solvents and also they are easily processed onto solid substrates.
关键词： Visible-light absorption,Conjugated polymers,Photocatalysis,Charge transfer,Energy transfer
更新于2025-09-23 15:23:52
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Versatile and Switchable Responsive Properties of a Lanthanide-Viologen Metal-Organic Framework
摘要： Metal–organic frameworks (MOFs) provide intriguing platforms for the design of responsive materials. It is challenging to mobilize as many components as possible of a MOF to collaboratively accomplish multiple responsive properties. Here, reversible photochromism, piezochromism, hydrochromism, ionochromism, and luminescence modulation of an ionic Eu(III) MOF is reported furnished by cationic electron-deficient viologen units and exchangeable guest anions. Mechanistically, the extraordinarily versatile responsive properties are owed to electron transfer (ET), charge transfer (CT), and energy transfer, involving viologen as electron acceptor, anion as electron donor, luminescing Eu(III) as energy donor, and anion-viologen CT complex or ET-generated radical as energy acceptor (luminescence quencher). Moreover, guest anions and waters provide flexible handles to control the ET-based responsive properties. Water release/reuptake or exchange with organic solvents can switch on/off the response to light, while reversible anion exchange can disenable or awaken the responses to pressure, light, and water release/reuptake. The impacts of water and anions on ET are justified by the high polarity and hydrogen-bonding capability of water, the different electron donor strength of anions, and the strong I?-viologen CT interactions. The rich responsive behaviors have great implications for applications such as pressure sensors, iodide detection, and chemical logic gates.
关键词： metal–organic frameworks,electron transfer,charge transfer,luminescence switches,piezochromism
更新于2025-09-23 15:23:52
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Highly Selective Fluorescent Probe Based on 2-(2′-Dansylamidophenyl)-Thiazole for Sequential Sensing of Copper(II) and Iodide Ions
摘要： A novel highly selective fluorescent probe based on 2-(20-dansylamidophenyl)-4-phenylthiazole (1) is developed for sequential sensing of copper(II) and iodide ions in acetonitrile. The fluorescence mechanism is based on cation-induced inhibition of excited-state intramolecular hydrogen transfer, intramolecular charge transfer, and metal–ligand electron/charge transfer. Subsequent iodide-induced extrusion of copper(II) results in partial revival of fluorescence. Probe 1 and its ensemble with copper (II) show high selectivity for copper(II) and iodide ions, respectively, in acetonitrile solution.
关键词： Excited-state intramolecular hydrogen transfer,I?,Cu2+,Intramolecular charge transfer,Dansyl-thiazole conjugate
更新于2025-09-23 15:23:52
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2-(1,1-dioxidobenzo[b]thiophen-3(2H)-ylidene)malononitrile (BTD) Based Styryl Chromophores- Solvatochomic and Computational Investigation of Linear and NLO properties
摘要： Linear and nonlinear optical properties of the twelve styryl dyes are investigated using density functional theory (DFT). Range-separated hybrid CAM-B3LYP and global hybrid BHandHLYP estimate high second order hyperpolarizability. Mean polarizability (α0), polarizability anisotropy (Δα), static first-order hyperpolarizability (β0) and second hyperpolarizability (γ) were found to be overestimated in CAM-B3LYP than in BHandHLYP. As bond length alternation (BLA) increases first order hyperpolarizability increases. Multilinear regression analysis (MLR) shows the solvent basicity, polarizability and dipolarizability are responsible for absorption solvatochromism. The ratio of the dipole moments increases as donor strength and conjugation increases which support charge transfer. The figure of merit (FOM) and intrinsic hyperpolarizability found more in chromophores with dialkylamine donors. As the stability indicated by electrophilicity indices decreases the hyperpolarizability increases. Interrelationships between α0, β0 and γ were evaluated and it shows good linear fit. Absorption is red shifted and hyperpolarizability increases with the amplitude of the sine-shaped potential along the conjugation chain. A high molecular electrostatic potential was observed in dyes containing 2-piperidinothiophene donor.
关键词： NLO,Charge transfer,DFT and TD-DFT,Absorption,Solvatochromism
更新于2025-09-23 15:23:52
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Effect of H?SO? Solution Treating on the Adhesion, Charge Transfer and Catalytic Performance of Screen‐Printed PEDOT:PSS
摘要： Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films screen-printed on fluorine-doped tin oxide (FTO) substrates, to improve their charge transfer efficiency. Different H2SO4 solutions including concentrated H2SO4 and H2SO4 diluted with H2O or dimethyl sulfoxide (DMSO) were adopted during the post-treatment. The adhesion of the as-treated films was evaluated by adhesive tape peeling tests, the surface morphology and vertical charge transfer from the films to the substrates were investigated by current-sensing atomic force microscopy, and the catalytic activities toward I3- reduction of PEDOT:PSS films were characterized via electrochemical measurements. It is discovered that selecting proper H2SO4 solutions is crucial to improve the charge transfer efficiency and catalytic performance while maintaining the reliable adhesion of the film on the substrates, and H2SO4/DMSO performs best as the solution for post-treatment. A schematic mechanism was proposed based on different interactions among solution, PEDOT:PSS and the substrate in the case of various post-treatment solutions.
关键词： charge transfer,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate),screen printing,catalysis,post-treatment
更新于2025-09-23 15:23:52
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3D graphene/AgBr/Ag cascade aerogel for efficient photocatalytic disinfection
摘要： To design semiconductor-based photocatalysts with efficient charge carriers separation and transfer remains an enduring goal of artificial photosynthesis toward target redox reactions. Herein, we report a cascade monolith composite of ternary reduced graphene oxide aerogel/silver bromide/silver (RGA/AgBr/Ag) with efficient charge carriers separation, which exhibits much higher activity than bare AgBr toward photocatalytic bacteria inactivation. Mechanistic studies reveal that the reduced graphene oxide aerogel (RGA) scaffold and Ag nanoparticles serve as electron relay mediators to promote the charge carriers separation and transfer. In addition, the metallic Ag nanoparticles derived from the photoreduction of AgBr during the photocatalytic disinfection can further boost the separation of charge carriers. Control experiments demonstrate that the surface plasmon resonance (SPR)-excited hot electrons of Ag nanoparticles also contributes to enhancing the photoactivity of RGA/AgBr/Ag. As such, the synergy of multiple electron transfer behavior integratively leads to the boosted photocatalytic performance of such RGA/AgBr/Ag aerogel for bacteria inactivation with convenient recyclable operability.
关键词： charge transfer,aerogel,silver bromide,Ag nanoparticles,reduced graphene oxide
更新于2025-09-23 15:23:52
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Graphdiyne: A promising nonlinear optical material modulated by tetrahedral alkali-metal nitrides
摘要： A new series of the functionalized graphdiyne (GDY) material was designed by adsorbing the tetrahedral Li3NM molecules on the largely delocalized π-conjugated GDY surface, namely Li3NM@GDY (M = Li, Na, K), and its structure, chemical stability, electronic property, and the first hyperpolarizability were investigated by using the density functional theory computations. Our results reveal that the Li3NM molecules can interact with three triangular holes on the GDY surface, in which the van der Waals interactions play a crucial role in enhancing the structural stability. Meanwhile, the total NPA charges on the Li3NM molecules are gradually increased from Li to K, and the Li3NM molecules can transfer an electron to GDY, forming intramolecular electron donor and acceptor pairs. All of studied complexes exhibit the giant static first hyperpolarizabilities (βtot), up to ~2.88 × 105 a.u. for Li3NK@GDY, which can be explained by two-level expression from the TDDFT calculations. This study will inevitably stimulate further synthesis of the novel graphdiyne-based nonlinear optical materials.
关键词： Graphdiyne,Electronic structure,TDDFT,Charge transfer,Nonlinear optical property
更新于2025-09-23 15:23:52
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Facet-Dependent Photocatalytic Behaviors of ZnS-Decorated Cu <sub/>2</sub> O Polyhedra Arising from Tunable Interfacial Band Alignment
摘要： ZnS particles were grown over Cu2O cubes, octahedra, and rhombic dodecahedra for examination of their facet-dependent photocatalytic behaviors. After ZnS growth, Cu2O cubes stay photocatalytically inactive. ZnS-decorated Cu2O octahedra show enhanced photocatalytic activity resulting from better charge carrier separation upon photoexcitation. Surprisingly, Cu2O rhombic dodecahedra give greatly suppressed photocatalytic activity after ZnS deposition. Electron paramagnetic resonance (EPR) spectra agree with these experimental observations. Time-resolved photoluminescence (TRPL) profiles provide charge transfer insights. The decrease in the photocatalytic activity is attributed to an unfavorable band alignment caused by significant band bending within the Cu2O (110)/ZnS (200) plane interface. A modified Cu2O–ZnS band diagram is presented. Density functional theory (DFT) calculations generating plane-specific band energy diagrams of Cu2O and ZnS match well with the experimental results, showing charge transfer across the Cu2O (110)/ZnS (200) plane interface would not happen. This example further illustrates that the actual photocatalysis outcome for semiconductor heterojunctions cannot be assumed because interfacial charge transfer is strongly facet-dependent.
关键词： interfacial charge transfer,zinc sulfide,cuprous oxide,facet-dependent properties,heterojunctions,band alignment
更新于2025-09-23 15:23:52