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Exploring the Carrier Dynamics in Zinc Oxide-Metal Halide Based Perovskites Nanostructures: Towards Reduced Dielectric Loss and Improved Photocurrent
摘要： Metal-halide based perovskites have emerged as a potential candidate for optoelectronic applications due to their impressive performance achieved by tuning the optical/electrical properties through tailoring the perovskite nanostructures. Herein, we report the synthesis of composite nanostructures by incorporation of ZnO (~6 nm) into CsPbBr3 (CPB) perovskite framework, which has significant enhancement of photocurrent, due to efficient interfacial charge separation and reduced dielectric loss. Detailed steady state and time resolved PL studies have been carried out to understand charge transfer dynamics in CsPbBr3/ZnO nanostructure composite system. Femtosecond transient absorption and broadband dielectric spectroscopy studies were carried out to determine the charge carrier relaxation and transfer mechanism. Redox energy level diagram suggests photo-excited electron from conduction band (CB) CPB can be transferred to the CB of ZnO NP due to thermodynamic viability. Ultrafast studies reveal the electron transfer take place from the perovskite nanostructures to ZnO NP within ～500 fs and limits of the recombination process by efficient charge separation and charge accumulation at the interfaces. Dielectric studies also reveal reduced charge leakage in composite nanostructures with efficient charge separation by facilitating the charge accumulation at the interfaces. Overall, the efficient charge transfer and slow carrier recombination with reduced dielectric losses significantly improved the photocurrent behavior CsPbBr3/ZnO nanostructure composite system as desired for optoelectronic devices.
关键词： ZnO,charge transfer dynamics,optoelectronic applications,dielectric loss,photocurrent,Metal-halide based perovskites,CsPbBr3
更新于2025-09-23 15:21:01
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Charge transfer dynamics and catalytic performance of a covalently linked hybrid assembly comprising a functionalized cobalt tetraazamacrocyclic catalyst and CuInS <sub/>2</sub> /ZnS quantum dots for photochemical hydrogen production
摘要： Although the cobalt complex, [Co(CR)X2]+ (CR ? 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene), has been studied as a catalyst for electro- and photochemical H2 generation and CO2 reduction for more than thirty years, only the unfunctionalized one was used as a free catalyst in bulk solutions. Considering that the immobilization of functionalized molecular catalysts (MCs) on the surface of light harvesting materials through a stable covalent linkage was often an effective strategy to boost the activity of semiconductor/MC hybrid photocatalytic systems, we prepared the first anchoring group-functionalized [Co(CR)X2]+ complex (C1, X ? Br), which bears a (20,60-dicarboxypyridin-40-yl) group at position 15 of the macrocyclic ligand. The covalent attachment of C1 to the surface of CuInS2/ZnS (CISZ) core–shell quantum dots (QDs) afforded the C1@CISZ hybrid assembly. Comparative studies on the visible-light-induced H2 evolution performances of C1@CISZ and the non-bonded reference system comprising the unfunctionalized [Co(CR)Br2]+ complex (C2) and CISZ QDs (denoted as C2+CISZ) revealed that the photocatalytic activity of C1@CISZ was twice to thrice as high as that of C2+CISZ under the same conditions. Appealingly, the isolated C1@CISZ assembly was more stable than the C2+CISZ system in long-term photolysis. Moreover, photoluminescence (PL) and transient absorption (TA) spectroscopic studies demonstrated that covalent immobilization of C1 on the surface of CISZ QDs accelerated the electron transfer from QDs to the catalyst and meanwhile retarded the charge recombination process on the surface of QDs. The evidently improved charge separation efficiency resulted in the higher activity of the hybrid assembly C1@CISZ than that of C2+CISZ for photocatalytic hydrogen production.
关键词： photochemical H2 generation,cobalt complex,photocatalytic hydrogen production,CO2 reduction,charge transfer dynamics,CuInS2/ZnS quantum dots
更新于2025-09-16 10:30:52
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Donor–Acceptor Distance-Dependent Charge Transfer Dynamics Controlled by Metamaterial Structures
摘要： Capability to control charge transfer dynamics in donor-acceptor molecule is important for efficient optoelectronic devices. Charge transfer dynamics is governed by thermodynamics of donor-acceptor charges in a given dielectric environment. Metamaterial structure has been shown to be able to control charge separation and charge recombination processes via nonlocal effect on dielectric permittivity for a fixed donor-acceptor distance organic film. Here, we report the influence of metamaterial structure on the donor-acceptor distance dependence of electron transfer process occurring in liquid crystalline organic semiconductor thin films. By examining charge recombination rate in three different donor-acceptor distances, it is found that the barrier height β increases from 0.084 ??1 to 0.137 ??1 by 63% in the presence of metal-dielectric multilayered metamaterial structures. Based on Marcus theory on charge transfer process, we show that the further increase of driving force for a larger donor-acceptor distance is mainly responsible for the barrier height increase in the presence of multi-layered metamaterial substrate when compared with glass substrate. This study will provide a significant step forward in enabling more efficient hybrid organic-optoelectronic devices associated with charge transfer process.
关键词： Charge transfer dynamics,Organic semiconductors,Metamaterials,Marcus Theory,Nonlocal effect
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Function of Photoanode: Charge Transfer Dynamics, Challenges, and Alternative Strategies
摘要： The increase in population demanded heavy energy requirements that accelerated the depletion of fossil fuels [1]. Among several renewable resource-based alternatives, dye-sensitized solar cell (DSSC) is one of the cost-effective and potential substitutes to silicon solar cells that emerged in the early 1990s in the field of photovoltaics, as it involves inexpensive components and simple fabrication process. DSSC is entirely different from the conventional p/n junction solar cells in terms of operating principle; however, it adopts the principle of natural photosynthesis process and, therefore, is it is often addressed as artificial photosynthesis. The monolayer of dye molecules on the photoanode functions like chlorophyll in plants and absorbs the incident light to generate both positive and negative charge carriers in the cell.
关键词： photoanode,dye-sensitized solar cell,charge transfer dynamics,renewable energy,DSSC
更新于2025-09-12 10:27:22
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Nonequilibrium Environment Dynamics in a Frequency-Dependent Polarizable Embedding Model
摘要： Hybrid quantum mechanical/molecular mechanical (QM/MM) models are some of the most powerful and computationally feasible approaches to account for solvent effects or more general environmental perturbations on quantum chemical systems. In their more recent formulations (known as polarizable embedding) they can account for electrostatic and mutual polarization effects between the QM and the MM subsystems. In this paper, a polarizable embedding scheme based on induced dipoles that is both able to describe electron evolution of the embedded QM system in an efficient manner as well as to capture the frequency dependent behavior of the solvent is proposed, namely ωMMPol. The effects of this frequency dependent solvent on a time-dependent model system — the Rabi oscillations of H+2 in a resonant field — are considered. The solvent is shown to introduce only mild perturbations when the excitation frequencies of the solvent and the solute are off-resonant. However, the dynamics of the H+2 are fundamentally changed in the presence of a near-resonant excitation solvent. The effectiveness of ωMMPol to simulating realistic chemical systems is demonstrated by capturing charge transfer dynamics within a solvated system.
关键词： charge transfer dynamics,polarizable embedding,Rabi oscillations,QM/MM models,frequency-dependent polarizability,electron dynamics
更新于2025-09-10 09:29:36