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Realizing efficiency improvement of polymer solar cells by using multi-functional cascade electron transport layers
摘要： Contact property between metal oxide electron transport layer (ETL) and active layer is one of the key factors to the performance of polymer solar cells (PSCs). To achieve better lattice matching and fewer defects, indium trioxide (In2O3) and zinc oxide (ZnO) (In2O3/ZnO) were used as the inorganic composite ETL, combining with an organic material PCBM as interface layer to obtain homogeneous phase separation of the active layer. The resulting device demonstrates a high fill factor of 69.83% and power conversion efficiency of 9.036% for PTB7:PC71BM based PSCs. Moreover, the acceptor material of PCBM serving as interface layer can interact with donor material of active layer to promote the exciton dissociation. This study provides a new method to improve the performance of PSCs by using multi-functional cascade electron transport layers.
关键词： Lattice matching,Electron transfer,In2O3/ZnO/PCBM cascade layers,Acceptor,Light absorption
更新于2025-09-19 17:13:59
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Study of Interfacial Charge Transfer from an Electron Rich Organic Molecule to CdTe Quantum Dot by using Sterna??Volmer and Stochastic Kinetic Models
摘要： Photoinduced electron transfer from N-methylaniline (NMA) to a photoexcited CdTe quantum dot (QD*) is studied in toluene. The PET mechanism at low to moderate quencher (NMA) concentrations (< 0.08 M) remains mostly collisional with some contributions from QD-NMA complex formation. However, at high quencher concentrations (> 0.10 M), QDs form larger numbers of static complexes with NMA molecules leading to a steep positive deviation in the steady-state Stern–Volmer curves. An isothermal titration calorimetry (ITC) study confirms the formation of QD-NMA complexes (K ~ 150 M?1) at high quencher concentrations. Fitting our experimental data using a stochastic kinetic model indicates that the number of NMA molecules attached per QD at highest NMA concentration (~ 0.16 M) used in this study decreases from ~ 0.76 to ~ 0.47 with reducing the QD size from ~ 5.2 nm to ~ 3.2 nm. However, the PET rate increases with decreasing QD size, which is commensurate with the observation that the chemical driving force (ΔG) increases with decreasing the QD particle size. We have analyzed the PET kinetics mainly by using Stern-Volmer fittings. However, in some cases Tachiya’s stochastic kinetic model is used for stoichiometric analysis, which seems to be useful only at high quencher concentrations. The measured PET rate coefficients in all the cases are found to be at least an order of magnitude lower when compared to the diffusion-controlled rate of the reaction medium.
关键词： quantum dot,time-resolved fluorescence,photoinduced electron transfer,Stern–Volmer analysis,bimolecular quenching
更新于2025-09-19 17:13:59
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Controlled synthesis of azobenzene-containing block copolymers both in the main- and side-chain from SET-LRP polymers via ADMET polymerization
摘要： Novel ABA triblock copolymer contained azobenzene (azo) chromophores both in the main- and side-chain was designed and synthesized via combination of single electron transfer-living radical polymerization (SET-LRP) and acyclic diene metathesis (ADMET) polymerization. The α-bromoester end group of side-chain azo-polymer prepared in SET-LRP system using acrylate bearing azo group as monomer was reacted with potassium acrylate to yield azo-polymer with the chain end of α-acrylate, which acted as a monofunctional macromolecular chain stopper for subsequent ADMET polymerization of azo-functionalized α,ω-diene monomer to finally controllable synthesize ABA triblock azo-copolymer. The diluted solutions of main-chain ADMET azo-homopolymer, side-chain SET-LRP azo-homopolymer, and main-side chains azo-copolymer exhibited different photoisomerization behaviors (maximum absorption and rate of photoisomerization) under the irradiation of UV and visible light. All these interesting results could provide a guide for the design of photosensitive materials.
关键词： photoresponsive polymer,Single electron transfer-living radical polymerization,acyclic diene metathesis polymerization
更新于2025-09-19 17:13:59
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Light <b>-</b> driven deracemization enabled by excited <b>-</b> state electron transfer
摘要： Deracemization is an attractive strategy for asymmetric synthesis, but intrinsic energetic challenges have limited its development. Here, we report a deracemization method in which amine derivatives undergo spontaneous optical enrichment upon exposure to visible light in the presence of three distinct molecular catalysts. Initiated by an excited-state iridium chromophore, this reaction proceeds through a sequence of favorable electron, proton, and hydrogen-atom transfer steps that serve to break and reform a stereogenic C–H bond. The enantioselectivity in these reactions is jointly determined by two independent stereoselective steps that occur in sequence within the catalytic cycle, giving rise to a composite selectivity that is higher than that of either step individually. These reactions represent a distinct approach to creating out-of-equilibrium product distributions between substrate enantiomers using excited-state redox events.
关键词： stereogenic C–H bond,excited-state electron transfer,iridium chromophore,deracemization,asymmetric synthesis
更新于2025-09-19 17:13:59
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Efficient Wastewater Remediation Enabled by Self-Assembled Perovskite Oxide Heterostructures with Multiple Reaction Pathways
摘要： Advanced oxidation processes (AOPs) are promising for the removal of retardant organic pollutants in water. However, traditional free-radicals-dominated AOPs are often limited by poor tolerance to water characteristics. Recently, creating nonradical processes has been considered as an effective strategy to overcome this limitation, while the function and mechanism of nonradical processes are still unclear in the important oxides catalytic systems. Herein, the nonradical-dominated peroxymonosulfate (PMS)-based AOPs are triggered on a heterostructural perovskite nanocomposite catalyst (La0.4Sr1.05MnO4?δ), which is constructed from single and Ruddlesden?Popper perovskite phases by a facile self-assembled synthesis method. Noticeably, the phenol degradation rate of the heterostructural nanocomposite oxide is ～2 times that of its individual components. This activity enhancement can be attributed to the abundant active oxygen vacancies, strong affinity to the reactants, and high-electron-transfer efficiency in the unique heterointerface of the nanocomposite. Furthermore, a ternary mechanism is unveiled: contaminants are oxidized not only by the function of radicals and singlet oxygen evoked from the active sites of perovskites but also by the transfer of their electrons to PMS via the beneficial surface of a heterostructral catalyst. This study provides new insights into nonradical-based AOPs derived from hybrid metal oxides in a PMS system.
关键词： Nonradical-based AOPs,Peroxymonosulfate activation,Phenol degradation,Electron-transfer pathways,Perovskite nanocomposites
更新于2025-09-19 17:13:59
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Excited-state proton-coupled electron transfer within ion pairs
摘要： The use of light to drive proton-coupled electron transfer (PCET) reactions has received growing interest, with recent focus on the direct use of excited states in PCET reactions (ES-PCET). Electrostatic ion pairs provide a scaffold to reduce reaction orders and have facilitated many discoveries in electron-transfer chemistry. Their use, however, has not translated to PCET. Herein, we show that ion pairs, formed solely through electrostatic interactions, provide a general, facile means to study an ES-PCET mechanism. These ion pairs formed readily between salicylate anions and tetracationic ruthenium complexes in acetonitrile solution. Upon light excitation, quenching of the ruthenium excited state occurred through ES-PCET oxidation of salicylate within the ion pair. Transient absorption spectroscopy identified the reduced ruthenium complex and oxidized salicylate radical as the primary photoproducts of this reaction. The reduced reaction order due to ion pairing allowed the first-order PCET rate constants to be directly measured through nanosecond photoluminescence spectroscopy. These PCET rate constants saturated at larger driving forces consistent with approaching the Marcus barrierless region. Surprisingly, a proton-transfer tautomer of salicylate, with the proton localized on the carboxylate functional group, was present in acetonitrile. A pre-equilibrium model based on this tautomerization provided non-adiabatic electron-transfer rate constants that were well described by Marcus theory. Electrostatic ion pairs were critical to our ability to investigate this PCET mechanism without the need to covalently link the donor and acceptor or introduce specific hydrogen bonding sites that could compete in alternate PCET pathways.
关键词： proton-coupled electron transfer,salicylate,ion pairs,ruthenium complexes,Marcus theory,excited-state
更新于2025-09-19 17:13:59
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Graphene quantum dot electrochemiluminescence increase by bio-generated H <sub/>2</sub> O <sub/>2</sub> and its application in direct biosensing
摘要： In this study, a novel signal-increase electrochemiluminescence (ECL) biosensor has been developed for the detection of glucose based on graphene quantum dot/glucose oxidase (GQD/GOx) on Ti foil. The proposed GQD with excellent ECL ability is synthesized through a green one-step strategy by the electrochemical reduction of graphene oxide quantum dot. Upon the addition of glucose, GOx can catalytically oxidize glucose and the direct electron transfer between the redox centre of GOx and the modified electrode also has been realized, which results in the bio-generated H2O2 for increase in GQD and realizes the direct ECL ECL signal detection of glucose. The signal-increase ECL biosensor enables glucose detection with high sensitivity reaching 5 × 10?6 to 1.5 × 10?3 mol l?1 in a wide linear range from 5 × 10?6 to 1.5 × 10?3 mol l?1. Additionally, the fabrication process of such GQD-based ECL biosensor is also suitable to other biologically produced H2O2 system, suggesting the possible applications in the sensitive detection of other biologically important targets (e.g. small molecules, protein, DNA and so on).
关键词： biosensor,graphene quantum dot,direct electron transfer,glucose oxidase,glucose
更新于2025-09-19 17:13:59
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Electron transfer mediated by iron carbonyl clusters enhance lighta??driven hydrogen evolution in water by quantum dots
摘要： Photocatalytic water splitting has become a promising strategy for converting solar energy into clean and carbon-neutral solar fuels via a low-cost and environmentally benign way. Hydrogen gas is such a potential solar fuel/energy carrier. In a classical artificial photosynthetic system, a photosensitizer is generally associated with a co-catalyst to convert photogenerated charge into (a) chemical bond(s). In the present study, assemblies consisting of CdSe quantum dots that are coupled with one of two [Fe2S2(CO)6] or [Fe3Te2(CO)9], using an interface-directed approach, have been tested as catalytic systems for hydrogen production in aqueous solution/organic solution. In the presence of ascorbic acid as a sacrificial electron donor and proton source, these assemblies exhibit enhanced activities for the rate of hydrogen production under visible light irradiation for 8 hrs in aqueous solution at pH 4.0 with up to 110 μmol of H2 per mg of assembly, almost 8.5 times that of pure CdSe quantum dots under the same conditions. Transient absorption and time-resolved photoluminescence spectroscopies have been used to investigate the charge carrier transfer dynamics in the quantum dot/iron carbonyl cluster assemblies. The spectroscopic results indicate that effective electron transfer from the molecular iron complex to the valence band of the excited CdSe quantum dots to the significantly inhibits the recombination of photogenerated charge carriers, boosting the photocatalytic activity for hydrogen generation; i.e. the iron clusters function as effective intermediaries for electron transfer from the sacrificial electron donor to the valence band of the quantum dots.
关键词： iron carbonyl cluster,quantum dot,electron transfer,proton reduction
更新于2025-09-19 17:13:59
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Role of Emissive and Non‐Emissive Complex Formations in Photoinduced Electron Transfer Reaction of CdTe Quantum Dots
摘要： Bimolecular photoinduced electron transfer (PET) from excited state CdTe quantum dot (QD*) to an electron deficient molecule 2,4-dinitrotoluene (DNT) is studied in toluene. We observed two types of QD-DNT complex formations; (i) non-emissive complex, in which DNT is embedded deep inside the surface polymer layer of QD and (ii) emissive complex, in which DNT molecules are attached to QDs but approach to the QD core is shielded by polymer layer. Because of its non-emissive nature, the lifetime of QD is not affected by dark complex formation, though the steady-state emission is greatly quenched. However, emissive complex formation causes both, lifetime and steady-state emission quenching. In our fitting model, consideration of Poisson distribution of the attached quencher (DNT) molecules at QD surface enables a comprehensive fitting to our time resolved data. QD-DNT complex formation was confirmed by an isothermal titration calorimetry (ITC) study. Fitting to the time resolved data using a stochastic kinetic model shows moderate increase (0.05 ns(cid:2)1 to 0.072 ns(cid:2)1) of intrinsic quenching rate with increasing the QD particle size (from (cid:3) 3.2 nm to (cid:3) 5.2 nm). Our fitting also reveals that the number of DNT molecules attached to a single QD increases from (cid:3) 0.1–0.2 to (cid:3) 1.2–1.7, as the DNT concentration is increased from (cid:3) 1 mm to 17.5 mm. Complex formation at higher quencher concentration assures that the observed PET kinetics is a thermodynamically controlled process where solvent diffusion has no role on it.
关键词： CdTe quantum dot,photo-induced electron transfer,donor-acceptor complex,time-resolved spectroscopy,fluorescence quenching
更新于2025-09-19 17:13:59
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Secondary Bonds Modifying Conjugatea??Blocked Linkages of Biomassa??Derived Lignin to Form Electron Transfer 3D Networks for Efficiency Exceeding 16% Nonfullerene Organic Solar Cells
摘要： Fabricating high-efficient electron transporting interfacial layers (ETLs) with isotropic features is highly desired for all-directional electron transfer/collection from an anisotropic active layer, achieving excellent power conversion efficiency (PCEs) on nonfullerene acceptor (NFA) organic solar cells (OSCs). The complicated synthesis and cost-consumption in exploring versatile materials arouse great interest in the development of binary-doping interlayers without phase separation and flexible manipulation. Herein, for the first time, a novel cathode interfacial layer based on biomass-derived demethylated kraft lignin (DMeKL) is proposed. Features of multiple phenolic-hydroxyl (PhOH) and uniform-distributed render DMeKL to exhibit an excellent bonding capacity with amino terminal substituted perylene diiminde (PDIN), and successfully form a high-efficient isotropic electron transfer 3D network. Synchronously, secondary bonds completely modify conjugate-blocked linkages of DMeKL, significantly enhance the electron transporting performance on cross-section and vertical-sections, and repair the contact of PDIN with active layer. The DMeKL/PDIN-based 3D-network exhibits well-matched work function (WF) (–4.34 eV) with cathode (–4.30 eV) and energy level of electron acceptor (–4.11 eV). DMeKL/PDIN-based NFAs-OSC shows excellent short-circuit current density (26.61 mA cm–2) and PCE (16.02%) beyond the classic PDIN-based NFA-OSC (25.64 mA cm–2, 15.41%), which is the highest PCEs among biomaterials interlayers. The results supply a novel method to achieve high-efficient cathode interlayer for NFAs-OSCs.
关键词： secondary bonds,nonfullerene acceptor organic solar cells,electron transfer 3D network,biomass-derived lignin,power conversion efficiency
更新于2025-09-19 17:13:59