Electron-hole Transfer Research Articles

Dramatically Prolonged Photoexcited Carrier Lifetimes in Group-III Monochalcogenide Heterostructures through Stacking Modulation.

Modulating the carrier dynamics to achieve the effective separation of photoexcited carriers is crucial for enhancing photoelectric conversion efficiency and advancing high-performance optoelectronic devices. A prototype group-III monochalcogenide heterostructure, GaSe/GaTe, has been proposed to exhibit a superior light-harvesting capability and highly tunable charge separation characteristics via nonadiabatic molecular dynamics (NAMD) simulations. The significant influence of stacking patterns on carrier dynamics is revealed, with electron (hole) transfer occurring within 97 (40) to 390 (126) fs, while the carrier lifetime is dramatically prolonged from 12 to 213 ns, facilitating effective electron-hole (e-h) pair separation. Notably, the AA' and A'A stacking configurations demonstrate remarkably extended carrier lifetimes of 213 and 161 ns, respectively, exceeding those observed in other 2D heterostructures. The weak nonadiabatic coupling and low-frequency phonon vibrational modes suppress e-h recombination, leading to a prolonged carrier lifetime. These findings offer atomic insights into stacking-dependent carrier dynamics, advancing 2D optoelectronic device design.

Excited State Structure and Decay Rates for Aggregates

ABSTRACTElectronic excited state in molecular aggregate or exciton states continue to attract great attention due to the increasing demands for applications of molecular optoelectronics and sensing technology. The working principle behind the application is closely related to the excited state structure and dynamic processes in molecular aggregate. In our previous review article (Aggregate 2021; 2: e91), we focused more on the molecular mechanism for aggregation‐induced emission process. Here, we are going to summarize our recent progress on theoretical investigations on the effects of excitonic coupling (J) and the intermolecular charge transfer (CT) on the excited state structure and dynamic processes. These are in general missing for molecular quantum chemistry studies. We will first present a novel definition of exciton coherence length which can present a bijective relation with the radiative decay rate and obviously we have clarified the confusion appeared in literature. Then, we will look at the CT effect for aggregate starting from a simple three‐state model coupled with quantum chemical calculation for molecular dimer and we focus on the intensity borrowing, which can turn H‐aggregate into emissive when the electron transfer and hole transfer integrals possessing the same sign and being large enough. We are able to propose a molecular descriptor to design molecular materials possibly possessing both high photoluminescence quantum yield and carrier mobility. Finally, we introduce our work on the modified energy gap law for non‐radiative decay rate in aggregates. We found there exist optimal J to minimize the non‐radiative decay loss.

2D layered BP/group-IV monochalcogenide van der Waals heterostructures for photovoltaics: electronic structure, band alignment, and carrier dynamics.

van der Waals heterostructures, composed of two-dimensional materials, have emerged as a promising platform for optoelectronic and photovoltaic applications. In this study, we constructed four vdW heterostructures, including BP/GeS, BP/GeSe, BP/SnS, and BP/SnSe, using BP and group-IV monochalcogenides as building blocks and investigated their potential for photovoltaic applications. First-principles calculations reveal that BP forms type II heterostructures with GeSe, SnS, and SnSe, while the BP/GeS system exhibits type I band alignment due to interfacial charge transfer. The structural stability of these heterostructures is confirmed by binding energy calculations, with the experimental synthesis of BP/SnSe providing additional validation. These heterostructures exhibit strong absorption in the infrared and visible regions, with predicted power conversion efficiencies ranging from 9.53% to 11.40%. Time-dependent density functional theory coupled with molecular dynamics simulations demonstrates ultrafast charge transfer in BP/GeSe, with electron transfer times (τ ≈ 147 fs) and hole transfer times (τ ≈ 839 fs), and the slower hole transfer rate is attributed to the limited mixing of higher energy levels and a coherent coupling mechanism. This work advances the fundamental understanding of BP/group-IV monochalcogenide van der Waals heterostructures and provides a robust theoretical foundation for their application in next-generation photovoltaic devices. Future research should focus on experimental validation, strain and stacking effects, and detailed device integration studies to fully harness their potential.

Polymeric Carbon Nitride Edged with Spatially Isolated Donor and Acceptor for Sunlight-Driven H2O2 Synthesis and In-Situ Utilization.

On-site H2O2 activation attracts much attention in energy conversion and environment remediation et al., yet remains challenging in its highly efficient and sustainable synthesis. Herein, we grafted a pair of spatially isolated donor (methoxyphenyl unit) and acceptor (anthraquinone unit) in polymeric carbon nitride edges, which induce directional electron-hole transfer to the two spatially separated dual active centers. Specifically, photogenerated electrons in the anthraquinone unit facilitate the 2e- ORR, while the methoxyphenyl unit, which gathers photogenerated holes, enables rapid 4e- WOR. More impressively, the anthraquinone unit also exhibits strong proton extraction capabilities to boost the generation of *OOH intermediates and H2O2. Consequently, the synthesized donor-polymeric carbon nitride-acceptor (DPA) catalyst shows a remarkable H2O2 yield of 6497.1 μM h-1 g-1 in pure water, surpassing traditional DP and PA catalysts. Because of its high efficiency, the H2O2 product can efficiently degrade and mineralize various organic contaminants in a continuous-flow self-Fenton reactor under sunlight irradiation. Our work presents an unprecedented approach to designing photocatalysts with efficient H2O2 synthesis and practical application from a molecular engineering perspective.

The Buddleja globosa (Matico) as natural Dye Sensitized Solar Cell: An experimental and theoretical studies based in TD-DFT/ periodic-DFT

The Buddleja globosa (Matico) as natural Dye Sensitized Solar Cell: An experimental and theoretical studies based in TD-DFT/ periodic-DFT

Accelerating Small Electron Polaron Dissociation and Hole Transfer at Solid-Liquid Interface for Enhanced Heterogeneous Photoreaction.

In a photocatalysis process, quick charge recombination induced by small electron polarons in a photocatalyst and sluggish kinetics of hole transfer at the solid-liquid interface have greatly limited photocatalytic efficiency. Herein, we demonstrate hydrated transition metal ions as mediators that can simultaneously accelerate small electron polaron dissociation (via metal ion reduction) and hole transfer (through high-valence metal production) at the solid-liquid interface for improved photocatalytic pollutant degradation. Fe3+, by virtue of its excellent redox ability as a homogeneous mediator, enables the BiVO4 photocatalyst to achieve drastically increased photocatalytic degradation performance, up to 684 times that without Fe3+. The enhanced performance results from Fe(IV) species production (via Fe3+ oxidation) induced by dissociation of small electron polarons (via Fe3+ reduction), featuring an extremely low kinetic barrier (5.4 kJ mol-1) for oxygen atom transfer thanks to the donor-acceptor orbital interaction between Fe(IV) and organic pollutants. This work constructs a high-efficiency artificial photosynthetic system through synergistically eliminating electron localization and breaking hole transfer limitation at the solid-liquid interface for constructing high-efficiency artificial photosynthetic systems.

Development of Semi-Empirical and Machine Learning Models for Photoelectrochemical Cells

We introduce a theoretical model for the photocurrent-voltage (I-V) characteristics designed to elucidate the interfacial phenomena in photoelectrochemical cells (PECs). This model investigates the sources of voltage losses and the distribution of photocurrent across the semiconductor–electrolyte interface (SEI). It calculates the whole exchange current parameter to derive cell polarization data at the SEI and visualizes the potential drop across n-type cells. The I-V model’s simulation outcomes are utilized to distinguish between the impacts of bulk recombination and space charge region (SCR) recombination within semiconductor cells. Furthermore, we develop an advanced deep neural network model to analyze the electron–hole transfer dynamics using the I-V characteristic curve. The model’s robustness is evaluated and validated with real-time experimental data, demonstrating a high degree of concordance with observed results.

Tumor microenvironment activated MXene-protected Cu2O heterojunctions induce tumor-specific cuproptosis for enhanced sono-immunotherapy

Tumor microenvironment activated MXene-protected Cu2O heterojunctions induce tumor-specific cuproptosis for enhanced sono-immunotherapy

Photocatalytic water splitting and charge carrier dynamics of Janus PtSSe/ζ-phosphorene heterostructure

On the basis of first-principles calculations and non-adiabatic molecular dynamics (NAMD) simulations, we explore the photocatalytic water splitting properties of PtSSe/ζ-Phosphorene heterostructure. This heterostructure possess semiconducting nature with high carrier mobility (≈ 103 cm2V− 1s− 1). The calculated high value of electron-hole recombination rate as compared to electron transfer rate and hole transfer rate, establish the Type-II mechanism more favorable for PtSSe/ζ-Phosphorene heterostructure. Further, the calculated value of solar-to-hydrogen (STH) conversion efficiency of PtSSe/ζ-Phosphorene exceeds to 10%, which makes it the potential candidate for commercial production of hydrogen for industrial use. STH conversion efficiency is further tunable on rotating one monolayer over other with specific angles in the heterostructure. Our study demonstrates PtSSe/ζ-Phosphorene heterostructure to be efficient Type II-scheme photocatalyst for water splitting.

Theoretical study the photophysical mechanism of fluorescent probe on detecting mitochondria-targeted hydrogen peroxide

The photophysical mechanism and dynamics behaviors of (E)-4-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)pyridin-1-ium (Compound 1) on detecting hydrogen peroxide (H2O2) has been theoretically studied. The boron ester in Compound 1 is cleaved when H2O2 is added to the solution, resulting in the formation of (E)-7-(diethylamino)-3-(2-(pyridin-4-yl)vinyl)-2H-chromen-2-one (Compound 2). Theoretical calculations show that the fluorescence spectra of the compounds exhibit a significant blue shift from 616 nm of Compound 1 to 542 nm of Compound 2 before and after the reaction, which are in good agreement with the experimental results (640 nm → 535 nm). The calculated electron–hole transfer distance of Compound 1 (5.986 Å) is larger than that of Compound 2 (3.544 Å), and Compound 1 is demonstrated to be charge transfer excitation while the Compound 2 is localized excitation, which results in a blue shift of the fluorescence spectra. The analysis of molecular electrostatic potential demonstrates that compound 1 has the highest electrostatic potential (4.60 eV) at the pyridine position and the lowest (−0.30 eV) at the oxygen atom of the coumarin moiety, suggesting that compound 1 undergoes fragmentation at this position. This study provides a theoretical explanation for the reaction mechanism of molecular probes.

Rational construction of defective Z-Scheme tandem heterojunction interfacial charge transfer channels for efficient uranium collection and resistance to biological contamination

Rational construction of defective Z-Scheme tandem heterojunction interfacial charge transfer channels for efficient uranium collection and resistance to biological contamination

Effectof Dual-Organic Cations on the Structure andProperties of 2D Hybrid Perovskites as Scintillators

Two-dimensional (2D)hybrid organic–inorganic perovskite(HOIP) crystals show promise as scintillating materials for wide-energyradiation detection, outperforming their three-dimensional counterparts.In this study, we synthesized single crystals of (PEA2–xBZAx)PbBr4 (x ranging from 0.1 to 2), utilizing phenethylammonium(C6H5CH2CH2NH3+) and benzylammonium (C6H5CH2NH3+) cations. These materials exhibitfavorable optical and scintillation properties, rendering them suitablefor high light yield (LY) and fast-response scintillators. Our investigation,employing various techniques such as X-ray diffraction (XRD), photoluminescence(PL), time-resolved (TR) PL, Raman spectroscopy, radioluminescence(RL), thermoluminescence (TL), and scintillation measurements, unveiledlattice strain induced by dual-organic cations in powder X-ray diffraction.Density functional theory analysis demonstrated a maximal 0.13 eVincrease in the band gap with the addition of BZA cation addition.Notably, the largest Stokes shift of 0.06 eV was observed in (BZA)2PbBr4. The dual-organic cation crystals displayed>80% fast component scintillation decay time, which is advantageousfor the scintillating process. Furthermore, we observed a dual-organiccations-induced enhancement of electron–hole transfer efficiencyby up to 60%, with a contribution of >70% to the fast componentofscintillation decay. The crystal with the lowest BZA concentration,(PEA1.9BZA0.1)PbBr4, demonstratedthe highest LYs of 14.9 ± 1.5 ph/keV at room temperature. Despitea 55–70% decrease in LY for BZA concentrations >5%, simultaneousreductions in scintillation decay time (12–32%) may work fortime-of-flight positron emission tomography and photon-counting computedtomography. Our work underscores the crucial role of dual-organiccations in advancing our understanding of 2D-HOIP crystals for materialsscience and radiation detection applications.

Synthesis of surfactant assisted Cu2ZnSnS4 (CZTS) photocatalysts for removal of dyes from wastewater

Synthesis of surfactant assisted Cu2ZnSnS4 (CZTS) photocatalysts for removal of dyes from wastewater

Perovskite half tandem v-shaped grating nanostructure solar cells: Improvement by light trapping and carrier transfer towards efficiency enhancement

Perovskite half tandem v-shaped grating nanostructure solar cells: Improvement by light trapping and carrier transfer towards efficiency enhancement

Mn3O4/ZnO-Al2O3-CeO2 mixed oxide catalyst derived from Mn-doped Zn-(Al/Ce)-LDHs: efficient visible light photodegradation of clofibric acid in water.

Mn3O4/ZnO-Al2O3-CeO2 catalyst was synthesized through a solid-state process from a 3% Mn-doped Zn-(Al/Ce) layered double hydroxide structure. Detailed structural and optical characterization using XRD, FTIR, UV-visible DRS, and TEM was conducted. By investigating clofibric acid (CA) degradation in aqueous solution, Mn3O4/ZnO-Al2O3-CeO2 photocatalytic activity was evaluated. The results show that the heterostructure mixed oxide catalyst has excellent CA photodegradation performance. Further, the characterization reveals that such photocatalytic efficiency can be attributed to two facts that are summarized in the optical properties and the synergic effect between Mn and Ce elements. The sample demonstrated a narrow band gap of 2.34 eV based on DRS. According to the experimental results of the photodegradation, after 120 min of irradiation, the photocatalyst exhibited the highest photocatalytic activity, with a degradation efficiency of 93.6%. Optimization outcomes indicated that maximum degradation efficiency was attained under the following optimum conditions: catalyst dose of 0.3 g/L, initial dye concentration of 20 mg/L, pH 3.86, and 120 min of reaction time. The quenching test demonstrates that photogenerated electrons and superoxide radicals are the most powerful reactive species. The catalyst could be useful in decreasing the photogenerated charges recombination, which offers more redox cycles simultaneously during the catalytic process. The strong Ce-Mn interaction and the formation of their different oxidation states offer a high degradation efficiency by facilitating electron-hole transfer. The introduction of Mn3O4 in the catalyst can effectively improve the visible absorption properties, which are beneficial in the photocatalytic process by reaching a high catalytic efficiency at a low cost.

Tunable Interfacial Electronic and Photoexcited Carrier Dynamics of an S-Scheme MoSi2N4/SnS2 Heterojunction.

Exploring and designing an efficient S-scheme heterojunction photocatalyst for water splitting are crucial. Herein, we report the interfacial electronics, photoexcited carrier dynamics, and photocatalytic performance for water splitting of the MoSi2N4/SnS2 van der Waals heterojunction under the modulation of an electric field and biaxial strain. Our results show that the MoSi2N4/SnS2 heterojunction has a direct band gap of 0.41 eV and obeys the S-scheme charge transfer mechanism. Further calculations of the photoexcited carrier dynamics demonstrate that the interfacial carrier recombination time is 7.22 ps, which is shorter than the electron (hole) transfer time of 39.5 ps (566 ps). Moreover, under the effect of a positive electric field and tensile strain, the S-scheme MoSi2N4/SnS2 heterojunction exhibits excellent visible-light absorption, satisfactory band-edge potentials, tunable interfacial charge transfer, and spontaneous hydrogen evolution reaction activity. The calculated STH efficiency indicates that a tensile strain of 2% is the most effective means of improving the photocatalytic performance of the S-scheme MoSi2N4/SnS2 heterojunction.

Investigation of g-C3N4/Ce2(WO4)3 Nanocomposites for the Removal of Basic Dyes.

Herein, we have synthesized pristine and g-C3N4-assisted Ce2(WO4)3 via a facile hydrothermal method. The structure was confirmed with the standard JCPDS card. g-C3N4 encapsulated the crystal and reduced the size. The Raman spectra revealed the presence of Ce-O, W-O stretching and bending vibrations. Electron hole transfer facilitation and controllable recombination were altered by g-C3N4 heterojunction with cerium tungstate. Ce2(WO4)3 possessed a larger band gap. As g-C3N4 was assisted, the band gap was reduced which facilitates Ce2(WO4)3 to utilize more visible light. The prepared photocatalysts were used to investigate the model pollutant removal with visible light. The pure Janus Green B sample showed lesser efficiency, as it does not show self-degradation under light. As Ce2(WO4)3 was added, it slightly improved the efficiency as it possesses lower electron hole transfer and high recombination. Thus, g-C3N4 was composited with Ce2(WO4)3 to make heterojunctions which will enhance the photo-excited electron and hole transfer and decrease e-/h+ recombination. The rate constant values of the photocatalysts were calculated, and the system follows the first-order pseudo-kinetic model. Ciprofloxacin, a well-known antibiotic, was also used to degrade under visible light. The pure sample showed lower efficiency, and the antibiotic was reduced well with the addition of prepared photocatalysts. The modification of Ce2(WO4)3 with the optimum-level g-C3N4 facilitated electron hole charge transfer, and numerous adsorbed dye molecules on the photocatalyst surface made 0.1 g g-C3N4-Ce2(WO4)3 a plausible photocatalyst for the water remediation process.

Electron, hole, and energy transfer dynamics in non-fullerene small-molecule acceptors.

When photoexcited, an organic photovoltaic (OPV) donor/acceptor (D/A) blend is expected to undergo charge separation (CS) through three channels: electron transfer, hole transfer, and energy transfer-induced electron/hole transfer. However, previous spectroscopic studies on various blends based on non-fullerene acceptors (NFAs) have not been able to directly characterize the dynamics of these processes, due to spectral overlap of the involved intermediate species. Herein, we study the excited-state dynamics of D/A blends composed of PBDB-T (D) and a L-series NFA (L4 or L5) and show that the species responsible for these processes in the PBDB-T/L4 blend can be spectroscopically identified, allowing us to disentangle their dynamics. Moreover, we confirm the occurrence of photoinduced CS in neat L4 and L5 films, providing direct evidence that CS can occur under nearly zero driving force in OPV systems. Further density functional theory calculations suggest that specific molecular packing patterns may play an important role in facilitating CS.

The Zn Vacancy-Mediated De-Accumulation Based Process for Hydrogen Production Performance Promotion of 1D Zn─Cd─S Nanorods.

Due to their anisotropy, 1D semiconductor nanorod-based materials have attracted much attention in the process of hydrogen production by solar energy. Nevertheless, the rational design of 1D heterojunction materials and the modulation of photo-generated electron-hole transfer paths remain a challenge. Herein, a ZnxCd1-xS@ZnS/MoS2 core-shell nanorod heterojunction is precisely constructed via in situ growth of discontinuous ZnS shell and MoS2 NCs on the Zn─Cd─S nanorods. Among them, the Zn vacancy in the ZnS shell builds the defect level, and the nanoroelded MoS2 builds the electron transport site. The optimized photocatalyst shows significant photocatalytic activity without Platinum as an auxiliary catalyst, mainly due to the new interfacial charge transfer channel constructed by the shell vacancy level, the vertical separation and the de-accumulation process of photo-generated electrons and photo-generated holes. At the same time, spectral analysis, and density functional theory (DFT) calculations fully prove that shortening difference of speed between the photogenerated electron and hole movement process is another key factor to enhance the photocatalytic performance. This study provides a new path for the kinetic design of enhanced carrier density by shortening the carrier retention time of 1D heterojunction photocatalysts with improved photocatalytic performance.

Preparation and photocatalytic activity of CoFe2O4 nanoparticle modified rod-like Mn0.3Cd0.7S photocatalysts with S-scheme heterojunction

Preparation and photocatalytic activity of CoFe2O4 nanoparticle modified rod-like Mn0.3Cd0.7S photocatalysts with S-scheme heterojunction