Quantum Size Effect Research Articles

(Invited) Thermoelectric Transport in Nanostructured 3D Topological Insulators and Stacked 2D Materials / Ferecrystals

Research in thermoelectric (TE) quantum structures was greatly propelled by the pre[1]diction in the early 1990s of a significant boost in TE efficiency by quantum size effects. Recently, research interest has shifted from quantum size effects in conventional semiconductors toward new types of quantum materials (e.g., topological insulators [TIs], Weyl and Dirac semimetals) characterized by their nontrivial electronic topology. Bi2Te3, Sb2Te3, and Bi2Se3, established TE materials, are also TIs exhibiting a bulk bandgap and highly conductive and robust gapless surface states. The signature of the nontrivial electronic band structure on the TE transport properties can be best verified in transport experiments using nanowires and thin films. However, even in nanograined bulk, the typical peculiarities in the transport properties of TIs can be seen. The signature of TI surface states on the thermoelectric properties of nanowire model systems will be discuss in depth and how these states can be modified by chemical modifications and in the vicinity of magnetic insulators.In the second part, we will report a different material class of stacked 2D materials based on metal monochalcogenides (MMCs), topological insulators and non-van der Waals (nvW) 2D Materials called ferecrystals via atomic layer deposition (ALD). The ferecrystals can be tailored to exhibit unusual properties such as low thermal conductivity or electronic or magnetic properties. The electronic properties of the 2D materials are modified by the interactions between the interwoven layered and non-layered materials. We have developed ferecrystal combinations, where the 2D material is the electronically active or in-active layer by selection of the bandgap for each layer. Figure 1

Hot Excitons Cool in Metal Halide Perovskite Nanocrystals as Fast as CdSe Nanocrystals.

The idea of phonon bottlenecks has long been pursued in nanoscale materials for their application in hot exciton devices, such as photovoltaics. Decades ago, it was shown that there is no quantum phonon bottleneck in strongly confined quantum dots due to their physics of quantum confinement. More recently, it was proposed that there are hot phonon bottlenecks in metal halide perovskites due to their physics. Recent work has called into question these bottlenecks in metal halide perovskites. Here, we compare hot exciton cooling in a range of sizes of CsPbBr3 nanocrystals from weakly to strongly confined. These results are compared to strongly confined CdSe quantum dots of two sizes and degrees of quantum confinement. CdSe is a model system as a ruler for measuring hot exciton cooling being fast, by virtue of its efficient Auger-assisted processes. By virtue of 3 ps time resolution, the hot exciton photoluminescence can now be directly observed, which is the most direct measure of the presence of hot excitons and their lifetimes. The hot exciton photoluminescence decays on nearly the same 2 ps time scale on both the weakly confined perovskite and the larger CdSe quantum dots, much faster than the 10 ps cooling predicted by transient absorption experiments. The smaller CdSe quantum dot has still faster cooling, as expected from quantum size effects. The quantum dots of perovskites show extremely fast hot exciton cooling, decaying faster than detection limits of <1 ps, even faster than the CdSe system, suggesting the efficiency of Auger processes in these metal halide perovskite nanocrystals and especially in their quantum dot form. These results across a range of sizes of nanocrystals reveal extremely fast hot exciton cooling at high exciton density, independent of composition, but dependent upon size. Hence these metal halide perovskite nanocrystals seem to cool heavily following quantum dot physics.

Anti-galvanic reaction induced interfacial engineering to reconstruct ternary colloid satellite platform for exceptionally high-performance redox-responsive sensor

The anti-galvanic reaction (AGR), which is a classic galvanic reaction (GR) with an opposite effect, is a unique phenomenon associated with the quantum size effect. This reaction involves the interaction between metal ions and nanoclusters, offering opportunities to create well-defined nanomaterials and diverse reductive behavior. In hence, in our work, we utilize the AGR to generate gold (Au), silver (Ag), and copper (Cu) satellite nanoclusters which have superior electromagnetic properties for Surface-enhanced Raman spectroscopy (SERS) sensor. As the AGR process, weak oxidant Cu2+ is selected to etched matrix Au@Ag NPs, reduced to Cu(0) or Cu(1) and generated the ultrasmall metal nanoparticles (Ag). To facilitate the AGR, we introduce the nucleophilic thiol 4-mercaptopyridine (4-Mpy) to bridge the metal ions or ultrasmall metal nanoparticles to reconstruct the satellite nanoclusters. These experimental displays that the AGR based biosensors has highly sensitivity for reductive molecule glucose. The liner ranges from 1 mmol/L to 1 nmol/L and alongs with a correlation coefficient and detection limit (LOD) of 0.999 and 0.14 nmol/L. Moreover, the AGR based biosensors exhibits remarkable stability and high repeatability with RSD 1.3 %. The food samples are tested to further investigate the accuracy and reliability of the method, which provides a novel and effective SERS method for the reduction molecules detection.

Functionalization of Violet Phosphorus Quantum Dots with Azo-Containing Star-Shape Polymer for Optically Controllable Memory

Quantum dots (QDs) are emerging as promising candidates for innovative memristive materials, owing to their distinct surface, quantum size, and edge effects. Recent research has focused on tailoring QDs with specific organic molecules to fine-tune charge transfer states between the host and grafted species, as well as enhancing their dispersibility and processability. Violet phosphorus (VP), a newly discovered two-dimensional phosphorus allotrope, offers excellent carrier dynamics, predictable modifiability, and superior oxidation resistance, making it a promising contender in this domain. In this study, we synthesized a rich azobenzene-containing star-shaped polymer diazonium salt (AzoSPD) to functionalize violet phosphorus quantum dots (VPQDs), with the dual objectives of enhancing organic dispersibility and introducing photo-switching capabilities. The synthesized AzoSPD–VPQDs exhibit intramolecular charge transfer characteristics under electrical stimuli of ambient conditions, displaying significant non-volatile rewriteable memory properties and a substantial switching ratio exceeding 2 × 103. Furthermore, the high resistance state (HRS) current can be enhanced by nearly 40 times under 465 nm illumination, enabling optoelectronic information sensing and storage within a single device. This work not only provides insights into enhancing the optoelectronic properties of QDs through functional organic molecular modification but also represents a pioneering exploration of the potential applications of VPQDs in novel memristors.

Enhancing Multiexcitonic Emission in Metal-Halide Perovskites by Quantum Confinement.

Semiconductor metal halide perovskite nanocrystals have been under intense investigation for their promise in a variety of optoelectronic applications, which arises from their remarkable properties of defect tolerance and efficient light emission. Recently, quantum dot versions of perovskite nanocrystals have been available, enabling investigation of how quantum size effects control optical function and performance in these quantum dots (QD), past their well-known covalent II-VI analogues. We perform time-resolved photoluminescence (t-PL) experiments on CsPbBr3 perovskite nanocrystals spanning in diameter from 5.8 nm strongly confined quantum dots to 18 nm weakly confined quantum dots. Experiments are performed with sufficient time resolution of 3 ps to observe the interaction energies and recombination kinetics from excitons to multiexcitons. Comparing the same sized QD reveals that perovskite QD have a larger radiative rate constant for emission from X than CdSe QD due to a larger oscillator strength. The multiexciton (MX) regime reveals that perovskite QD emit brightly and with more focused bandwidth than equivalent sized CdSe QD enabling more spectrally pure brightness. The MX kinetics reveals that the perovskite QD maintain efficient radiative decay, effectively competing with Auger recombination. These experiments reveal that the strongly confined QD of perovskites can be efficient multiexcitonic emitters, such as in high brightness light emitting diodes, especially in the blue.

Facile synthesis of carbon dots by the hydrothermal carbonization of avocado peels and evaluation of the photocatalytic property

The preparation of carbon quantum dots (CQDs) from agricultural waste sources stands out as a significant type of biomass-based nanomaterials. This is primarily because of their minute size, exceptional water solubility, lack of toxicity, and impressive stability. Here, carbon quantum dots (CQDs) were successfully prepared by a one-step hydrothermal method using the waste from Avocado peels and only water as solvent. Physicochemical properties of the CQDs were characterized by UV–vis, PL, FTIR, XRD, SEM, TEM, and HRTEM. The diameter of the CQDs was found to satisfy the quantum size effect and this was also supported by the reduced graphitization. The CQDs were used for the removal of methyl orange (MO), a common anionic dye, from an aqueous solution. The effectiveness of MO removal was directly related to the pH and the amount of the nanomaterial used. Under optimal experimental conditions, with a 7.5 mg catalyst dose, a 120-minute reaction time, and a pH of 10, the maximum degradation of MO (78 %) was achieved.

Shape and quantum size effects on the electronic structure, oscillator strengths and state lifetimes of helium-like quantum dots

Transition energies, electric static polarizability, oscillator strengths and state lifetimes of helium-like quantum dots are determined as a function of their shape and size. A configuration interaction approach based on B-spline functions is used. We found that, the oscillator strengths present an extremum around a low value of the dot radius whatever the shape of the confining potential. This extremum is due to the pressure on the energy levels in such a way that for a particular value of the dot radius, the second electron in the excited one-electron state reaches the borders of the confinement potential. The extremum position depends on the impurity charge and the oscillator strength value at this point changes with the potential well shape. As well, the increase of the effective mass involves the shift of the position of the oscillator strength extremum towards weak radius values. The first excited state lifetime globally increases with the dot radius and the reduction of the nuclear charge but presents a shoulder for a certain low value of the dot radius mostly marked for a triangular form of the confining potential.

MnFe2O4/polyaniline/diatomite composite with multiple loss mechanisms towards broadband absorption.

The research and development of absorbing materials with high absorbing capacity, wide effective absorption bandwidth, and lightweight has always been interesting. In this research, a facile hydrothermal method was used to prepare MnFe2O4, and the grain size of MnFe2O4 decreased with increasing hydrothermal temperature. When the size of MnFe2O4 nanoparticles is less than 10nm, its quantum size effect and surface effect make its electromagnetic microwave absorption performance greatly optimized. When the thickness of MnFe2O4-110 °C is 2.57mm, the minimum reflection loss (RLmin) is -35.28 dB. Based on this, light porous diatomite and a three-dimensional polyaniline network are introduced. Diatomite is used as the base material to effectively reduce the agglomeration of MnFe2O4 quantum dots. The relatively high surface area introduced by a three-dimensional network of polyaniline promotes the orientation, interfacial polarization, multiple relaxation, and impedance matching, thereby generating further dielectric loss. Additionally, the magnetic properties of manganese ferrite and the strong electrical conductivity of polyaniline play an appropriate complementary role in electromagnetic wave absorption. The RLmin of MnFe2O4/PANI/diatomite is -56.70 dB at 11.12GHz with an absorber layer thickness of 2.57mm. The effective frequency bandwidth (RL < -10 dB) ranges from 9.21 to 18.00GHz. The absorption mechanism indicates that the high absorption intensity is the result of the synergistic effect of impedance matching, conduction losses, polarization losses, and magnetic losses.

Size Quantization of the Electron Energy Spectrum in a Microscopic Semiconductor Crystal

The interband absorption spectrum of microscopic CdS crystals ranging in size from ~30 to 800 Å and dispersed in a transparent insulating matrix has been studied. There is a significant (~0.8-eV) shift of the fundamental absorption edge in the short-wavelength direction, and there are oscillations in the interband absorption spectrum caused by quantum size effect.

Quantum Size Effect in Three-Dimensional Microscopic Semiconductor Crystals

The exciton absorption spectrum of microscopic CuCl crystals grown in a transparent dielectric matrix has been studied. The size of the microscopic crystals was varied in a controlled manner from several tens of angstroms to hundreds of angstroms. There is a short-wave shift (of up to 0.1 eV) of the exciton absorption lines, caused by a quantum size effect.

Hyperfine splitting and ferromagnetism in CdS : Mn nanoparticles for optoelectronic device applications

Manganese (Mn) doped cadmium sulphide (CdS) nanoparticles were synthesized using a chemical method. It was possible to decrease CdS : Mn particle size by increasing Mn concentration. Investigation techniques such as ultraviolet−visible (UV−Vis) absorption spectroscopy and photoluminescence (PL) spectroscopy were used to determine optical properties of CdS : Mn nanoparticles. Size quantization effect was observed in UV−Vis absorption spectra. Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping CdS nanoparticles with Mn element. Orange emission was observed at wavelength ~630 nm due to 4T1 → 6A1 transition. Isolated Mn2+ ions arranged in tetrahedral coordination are mainly responsible for luminescence. Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of CdS nanoparticles were also discussed. The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy (AAS). Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction (XRD) technique. CdS : Mn nanoparticles show ferromagnetism at room temperature. Transmission electron microscopy (TEM) images show spherical clusters of various sizes and selected area electron diffraction (SAED) patterns show the polycrystalline nature of the clusters. The electronic states of diluted magnetic semiconductors (DMS) of Ⅱ−Ⅵ group CdS nanoparticles give them great potential for applications due to quantum confinement. In this study, experimental results and discussions on these aspects have been given.

Boron nitride nanosheet @ quantum‐sized diamond nanocrystal complex/epoxy nanocomposites with enhancing thermal conductivity and sufficient dielectric breakdown strength

AbstractWith the development of high‐voltage and high‐power devices in the direction of compactness, lightness and extreme working environments, the contradiction between thermal conductivity and dielectric breakdown strength is becoming more and more obvious. In this work, a novel boron nitride nanosheet with uniformly dispersed diamond nanocrystalline (abbreviated as BA@DN) was prepared via facile acidizing hydroxylation, in situ copolymerization self‐assembly of dopamine and blending process. The obtained hybrid filler was employed to embed into epoxy matrix, showing enhanced thermal conductivity and sufficient dielectric breakdown strength. For example, the through‐plane and in‐plane thermal conductivity of epoxy composite with 5% BA@DN‐2 reaches to 0.56 and 3.824 W/m K, respectively. The study proposes a modified plane thermal conductivity model. Based on calculations, it was found that the modified thermal conductivity of 5% BA@DN‐2 is 3.47 W/m K, which is significantly higher than that of pure EP, specifically 17.35 times higher. These findings are significant in terms of materials science. while its alternating current and direct current dielectric breakdown strength are 48.84 and 136.31 kV/mm, about 85.68% and 99.1% of pure epoxy, respectively. The mechanism of outstanding dielectric breakdown strength was analyzed via dielectric characteristic, partial discharge performance and the theory of quantum size effect. In addition, a modified multi‐core model with a multilevel overlapping interface is presented.Highlights The acidified diamond nanocrystals (DNs) were attached to dopamine‐coated boron nitride nanocrystals by a blending process. The small size effect of DNs allows the epoxy film to have both high thermal conductivity and high insulation properties. A thermal conductivity correction model is proposed to eliminate the effect of graphite layer on the film.

An ab-initio investigation of transition metal-doped graphene quantum dots for the adsorption of hazardous CO2, H2S, HCN, and CNCl molecules

The quantum confinement and size effects make graphene quantum dots (GQDs) remarkable candidates for sensing applications. Gas molecules can easily be adsorbed on GQDs because of their large specific areas and exposed edges. This computational work concerns the adsorption performance of pristine and transition metal [chromium (Cr) or nickel (Ni)]-doped coronene GQD to hazardous gases carbon dioxide (CO2), hydrogen sulfide (H2S), hydrogen cyanide (HCN), and cyanogen chloride (CNCl), along with structural properties such as bond length and angle, electronic properties including molecular orbital analysis, natural bond orbital and Mulliken charge analysis, spectroscopic properties of infrared and ultraviolet spectra, quantum theory of atoms in molecules with non-covalent interaction analysis, and sensing properties of recovery time, work function, and sensing response. As pristine GQDs show poor gas adsorption, doping with Cr and Ni enhance performance. The results of Cr-doped coronene GQD indicate that the gas molecules have strong interaction with GQDs as the computed adsorption energies are highly negative (−3.56, −3.81, −4.02, and −4.81 eV). Since the computed recovery times are extremely long, the Cr-doped GQDs can be used as removers of CO2, H2S, HCN, and CNCl gas molecules from specific environments. In the case of Ni-doped GQDs, only the interaction with CNCl yields chemisorption, with adsorption energy of −0.83 eV. However, the short recovery time (9.36 ms–93.6 s) indicates its potential candidature as a CNCl sensor.

Morphology of Bi(110) quantum islands on epitaxial graphene

Proximitized 2D materials present exciting prospects for exploring new quantum properties, enabled by precise control of structures and interfaces through epitaxial methods. In this study, we investigated the structure of ultrathin coverages formed by depositing high-Z element bismuth (Bi) on monolayer graphene (MLG)/SiC(0001). By utilizing electron diffraction and scanning tunneling microscopy, ultrathin Bi nanostructures epitaxially grown on MLG were studied. Deposition at 300 K resulted in formation of needle-like Bi(110)-terminated islands elongated in the zig-zag direction and aligned at an angle of approximately 1.75∘ with respect to the MLG armchair direction. By both strain and quantum size effects, the shape, the orientation and the thickness of the Bi(110) islands can be rationalized. Additionally, a minority phase of Bi(110) islands orthogonally aligned to the former ones were seen. The four sub-domains of this minority structure are attributed to the formation of mirror twin boundaries, resulting in two potential alignments of Bi(110) majority and minority domains with respect to each other, in addition to two possible alignments of the majority domain with respect to graphene. Notably, an annealing step at 410 K or lowering the deposition temperature, significantly increases the concentration of the Bi(110) minority domain. Our findings shed light on the structural control of proximitized 2D materials, showcasing the potential for manipulating 2D interfaces.

Silicon-Based Nanoelectronic Semiconductor Material and Its Surface-Enhanced Raman Image Signals

One-dimensional Zinc Oxide (ZnO) nanomaterials have important applications in devices, such as solar energy, sensors, and piezoelectric materials due to surface effects and quantum size effects. As a semiconductor material, Si has good thermal conductivity and low resistivity. A layer of n-type ZnO nanowires is grown on P-type monocrystalline silicon by transferring the Anodic Aluminum Oxide (AAO) template. The enhanced Raman effect on the surface is attempted by preparing n-type ZnO-P-type Si heterojunction nanostructures. This paper uses Si-based AAO as a template and uses electrochemical deposition method to prepare silicon-based nano-electronic semiconductor material ZnO/AAO/Si. According to SEM analysis, there are uniform pores on the surface of the material, and the cross-section shows that ZnO nanowires have been assembled into the AAO/Si structure. XRD analysis shows that ZnOn nanowires have a hexagonal wurtzite structure. In optoelectronic testing, through PL spectral analysis, the semiconductor material ZnO/AAO/Si has a strong yellow green emission peak near 574 nm. Field emission analysis shows that the β value of the ZnO field enhancement factor in the ZnO/AAO/Si structure is relatively high. The Surface-Enhanced Raman Spectroscopy (SERS) image signal experiment shows that the silicon-based nano-electronic semiconductor material prepared by electrochemical deposition method has good SERS characteristics. The SERS spectral intensity increases with the increase of the concentration of the detected substance and can be used as a SERS substrate to achieve Raman spectral image signal detection of chemical substances with low concentration.

Thermodynamic property of one-dimensional hydrogenic impurity in Nitride semiconductor quantum well

ABSTRACT The thermodynamic properties of one-dimensional (1-D) hydrogenic impurity in Nitride semiconductor quantum well have been investigated. Firstly, using a combination of the linear variational approach and the effective mass approximation, we obtain the eigen-energy of hydrogenic impurity states in AlN, GaN and InN quantum wells. Subsequently, we explore the quantum size effect on the thermodynamic properties of these low-dimensional semiconductor structures, revealing some novel and intriguing phenomena. It is found as the width of the quantum well is increased, the energy of hydrogenic impurity gets decreased, however, the thermodynamic parameters, such as the average energy, entropy and heat capacity of the hydrogenic impurity become increased. The physical origins of these peculiar phenomena are attributed to the competitive mechanism between the quantum confinement effect and Coulombic interaction between the electron and impurity. Finally, by conducting a comprehensive comparison of the thermodynamic parameters among GaN, InN, and AlN quantum wells, we propose an innovative strategy for modulating the thermodynamic properties of these low-dimensional semiconductor structures. This manipulation can be achieved not only through external factors such as temperature and quantum well size, but also by altering internal variables like the effective mass and relative dielectric constant of the semiconductor material. This study not only advances our understanding of the thermodynamic properties of hydrogenic impurities in semiconductor quantum wells, but also provides some theoretical guidance for practical applications in fields such as semiconductor physics, condensed matter physics, chemical physics, etc.

High-density and high-uniformity InAs quantum nanowires on Si(111) substrates

InAs nanowires (NWs) were grown on SiOx pinholes formed on Si(111) substrates by molecular beam epitaxy. Influences of electron-beam (EB) irradiation on the SiOx layer on the pinhole formation and the subsequent InAs NW growth were studied. As the EB irradiation dose increased, the pinhole density in the SiOx layer decreased. From atomic force microscopy, transmission electron microscopy, and x-ray photoelectron spectroscopy results, it was found that the pinhole etching of the SiOx layer by Ga droplets was suppressed by carbon adsorption due to the EB irradiation. By forming high-density pinholes on the SiOx layer without the EB irradiation, high-density InAs NWs with 1–2 × 1010 cm−2 were grown successfully, and the uniformity in the NW diameter improved. The standard deviation of the NW diameter was 1.8 nm (8.8%) for high-density NWs. In addition, the NW diameter decreased with decreasing EB dose, and the NW diameter was controlled by adjusting the diameter of Ga droplets forming the pinholes. As the NW diameter decreased, photoluminescence spectra of the NWs shifted to higher energies than the bandgap energy of the wurtzite InAs bulk. From these results, we successfully fabricated high-density and high-uniformity InAs NWs with quantum size effects on EB-unirradiated SiOx/Si(111).

Optical and temperature-dependent electrical and dielectric properties of ultrasound-synthesized CdS quantum dots

CdS quantum dots (QDs) were synthesized by the ultrasound-assisted chemical precipitation technique. The structure analysis revealed the presence of bi-structural cubic and hexagonal phases with an average crystallite size of 3 nm. The N2-adsorption isotherm exhibited the evolution of meso-/macro-porous interfaces with a pore size of 7.56 nm and a surface area of 44.41 m2·g−1. The improvement of the quantum size effect in CdS QDs resulted in the increase of optical bandgap to 2.52 eV compared with the corresponding bulk phase. However, the analysis of long-tail states absorption revealed a very small Urbach energy of about 76 meV compared with CdS QDs prepared by other techniques. The as-synthesized CdS QDs revealed high room-temperature DC conductivity of 2.56 × 10–6 Ω−1 · m−1 and very small activation energy of 268 meV facilitating tunnelling of the thermionically excited carrier through the high bandgap of CdS QDs. The frequency-dependent behavior of AC conductivity (σ AC) and dielectric constant (ε r) of CdS QDs were investigated at different temperatures in the range from 303 K to 453 K. It was observed that both σ AC and ε r were improved with increasing temperature up to 363 K followed by a sudden decrease at higher temperatures.

Semiconductor quantum dots as a mechanism to enhance charge transfer processes in polymer solar cells

The light trapping capability of thin film polymer solar absorber, composed of poly (3-hexylthiophene) and [6,6]–phenyl C61- butyric acid methyl ester (P3HT:PC60BM) blend, is improved using ZnS semiconductor quantum dots (QD) as third donor-acceptor (D:A) component. The inherent characteristics of the microwave-assisted synthesized ZnS QD, such as quantum size effect, and multiple exciton generation were leveraged in harvesting high energy photons, which resulted in a better exciton generation, dissociation, and effective charge transport in the polymer medium. The synthesized QD exhibited good phase purity, effective kinetic enhancement, and control of the aggregation process. Hence, the impact of ZnS QD on the performance of thin film polymer solar cells (TFPSC) is evident by a remarkable improvement in the measured photovoltaic parameters. Nonetheless, it is observed that the device performances are generally dependent on the concentration of the QD in the absorber layer. Consequently, the power conversion efficiency has increased by 58% at 3% concentration of QDs by weight. This is an interesting development of TFPSC fabricated under an ambient environment.

Electron Tunneling Fosters Solar-to-Hydrogen Energy Conversion.

Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light harvesting, quantum size effect, and abundant active sites. However, fine-tuning the photoinduced charge carrier over TMCs QDs to manipulate the directional charge-transfer pathway remains challenging, considering their ultrashort charge lifetime and slow charge-transfer kinetics. To this end, herein, MoSx/PDDA/TMCs QDs heterostructures were exquisitely designed by a simple and green electrostatic self-assembly strategy under ambient conditions, wherein tailor-made negatively charged TMCs QDs stabilized by mercaptoacetic acid (MAA) were precisely self-assembled on the positively charged polydiallyl dimethylammonium chloride (PDDA)-modified MoSx nanoflowers (NFs), forming a well-defined three-dimensional heterostructured nanoarchitecture. As an electron trapping agent, an MoSx NFs cocatalyst benefits the unidirectional electron transfer from TMCs QDs to the ideal active centers on the MoSx NFs surface by tunneling the ultrathin insulating polymer interim layer, thereby boosting the charge separation efficiency and endowing self-assembled MoSx/PDDA/TMCs QDs heterostructures with considerably increased photocatalytic hydrogen evolution activity (1.96 mmol·g-1·h-1) and admirable stability under visible light irradiation. Our work will provide new insights into smart regulation of directional charge transfer over TMCs QDs-based photosystems for solar energy conversion.