# Fileset

[2025A01222G_ACS AMI-accepted version.pdf](https://mdr.nims.go.jp/filesets/82a90e62-5570-4369-8ef4-92cf8ffee188/download)

## Creator

Kunjie Zhou, Jingyi Zhu, Ruisi Meng, Wei Zeng, Zhuo Xue, Chen Shen, Yueran Zhao, Yuchen Zhou, Mengyao Li, Yanan Wang, [Kenji Watanabe](https://orcid.org/0000-0003-3701-8119), [Takashi Taniguchi](https://orcid.org/0000-0002-1467-3105), Minliang Lai, Jia Lin, Sheng Wang

## Rights

This document is the Accepted Manuscript version of a Published Article that appeared in final form in ACS Applied Materials & Interfaces, copyright © 2025 American Chemical Society. To access the final published article, see https://doi.org/10.1021/acsami.5c05063.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Metal-Enhanced Photoluminescence in Perovskite Quantum Dots-hBN-Gold Film Mixed-Dimensional van der Waals Heterostructure](https://mdr.nims.go.jp/datasets/0335dfe4-1fc2-4613-aba0-be79da7403a1)

## Fulltext

Template for Electronic Submission to ACS Journals 1 Metal-enhanced Photoluminescence in Perovskite Quantum Dots-hBN-Gold Film Mixed-dimensional Van der Waals Heterostructure Kunjie Zhou1§, Jingyi Zhu1§, Ruisi Meng2§, Wei Zeng1, Zhuo Xue1, Chen Shen 1, Yueran Zhao3, Yuchen Zhou2, Mengyao Li2, Yanan Wang2, Kenji Watanabe4, Takashi Taniguchi5, Minliang Lai3*, Jia Lin2*, and Sheng Wang1,6* 1 Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, and School  of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, China  2 Department of Physics, Shanghai University of Electric Power, Shanghai 200090, China 3 School of Nano Science and Technology, Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu 215123, China 4 Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan 5 Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan 6 Wuhan Institute of Quantum Technology, Wuhan, Hubei 430206, China  *Email: mllai@ustc.edu.cn, jlin@shiep.edu.cn, shengwang16@whu.edu.cn    2 ABSTRACT All-inorganic cesium lead halide perovskite quantum dots (QDs) have emerged as promising materials for next-generation optoelectronic devices due to their exceptional photoluminescence (PL) properties, including high quantum yields and narrow emission linewidths. However, unlocking their full potential requires innovative strategies to further enhance and precisely tune their fluorescence efficiency. In this work, we present a novel 0D-2D-3D mixed-dimensional van der Waals (vdW) heterostructure comprising CsPbBr3 QDs, multilayer hexagonal boron nitride (hBN), and a gold (Au) nanoparticle film, achieving a remarkable 7-fold PL enhancement. We attribute this enhancement to the synergy of plasmon-induced enhancement of the incident electromagnetic field and an increased spontaneous emission rate via the Purcell effect, optimized by tuning the hBN spacer thickness to 26 nm. This heterostructure design provides new insights into metal-enhanced photoluminescence for perovskite quantum dots, and it offers a scalable platform to enhance efficiency in future optoelectronic applications. KEYWORDS: perovskite quantum dots, metal-enhanced photoluminescence, mixed-dimensional vdW heterostructure, surface plasmons, Purcell effect   3 INTRODUCTION All-inorganic halide perovskite quantum dots (QDs), exemplified by CsPbBr3 QDs, have garnered widespread attention in photonics and optoelectronics, due to their high quantum yields, narrow emission linewidths, and composition-tunable optical properties. These attributes make them ideal candidates for applications in light-emitting diodes (LEDs), solar cells, photodetectors, and quantum light sources.1–14 Despite significant progress in optimizing perovskite QD fluorescence through surface passivation, size engineering, and ligand exchange,15–19 their performance remains constrained by factors such as nonradiative recombination and environmental instability, necessitating novel enhancement strategies. Plasmonic nanostructures offer a powerful approach to boost the fluorescence of emitters by leveraging surface plasmons—collective oscillations of free electrons at metal-dielectric interfaces.20–31 When fluorophores are positioned near plasmonic surfaces, the local electromagnetic field is enhanced, and the radiative decay rate is amplified via the Purcell effect, increasing quantum yield.32,33 This metal-enhanced PL technique has proven effective for diverse materials, including transition metal dichalcogenides (TMDs), organic dyes, and semiconductor nanocrystals,34–39 yet its application to Perovskite QDs remains underexplored.  Concurrently, mixed-dimensional van der Waals (vdW) heterostructures—combining materials of different dimensionalities (e.g., 0D quantum dots, 2D layers, and 3D films)—have emerged as a versatile platform for tailoring optoelectronic properties, thanks to their atomically sharp interfaces and tunable band alignments.40–45 These systems enable precise control over light-matter interactions, making them ideal for integrating plasmonic enhancements with Perovskite QDs. Moreover, as an insulating 2D crystal, hexagonal boron nitride (hBN) features an atomically smooth surface with minimal dangling bonds and charged impurities, and its layered hexagonal  4 lattice structure with strong in-plane ionic bonding ensures chemical inertness and stability while maintaining excellent insulating properties even at monolayer thicknesses.41,46 These exceptional dielectric characteristics of hBN render it an ideal candidate for engineering van der Waals heterostructures and fabricating high-performance optoelectronic devices. In this study, we introduce a pioneering 0D-2D-3D mixed-dimensional vdW heterostructure composed of 0D semiconducting CsPbBr3 QDs, 2D insulating multilayer hBN, and 3D conducting gold (Au) nanoparticle film. This unique architecture, enabled by the 2D nature of hBN, allows for precise tuning of the PL emission of CsPbBr3 QDs by varying the thickness of the hBN spacer. We achieved a maximum PL enhancement of 7-fold at an hBN thickness of 26 nm with reduced PL lifetime, revealed by confocal scanning PL microscopy and fluorescence lifetime imaging microscopy (FLIM). Theoretical analysis and numerical simulations further corroborate the experimental observations, showing that both the plasmon-induced enhancement of the excitation field and the Purcell effect contribute to the observed PL enhancement. This work offers a scalable strategy for optimizing perovskite-based devices, including high-efficiency perovskite quantum dot light-emitting diodes (PeLEDs), photodetectors, and phototransistors,47–49 while laying the groundwork for the future development of mixed-dimensional vdW heterostructures in advanced optoelectronics. RESULTS AND DISUSSION QDs Synthesis and Heterostructure Fabrication We synthesized CsPbBr3 QDs using a hot-injection method, as detailed in the Supporting Information.54 Transmission electron microscopy (TEM) analysis (Figure 1a) revealed that the QDs exhibited a cubic morphology with an average size of 9.9 nm and a size dispersion of 13%. High-resolution TEM imaging (inset, Figure 1a) further confirmed the uniformity and single- 5 crystalline nature of the nanoparticles. Given that the Bohr diameter for Wannier-Mott excitons in CsPbBr3 is approximately 7 nm,1,14 our QDs, with dimensions comparable to this characteristic length scale, are expected to exhibit quantum confinement effects. The PL spectrum of CsPbBr3 QDs dispersed in hexane at room temperature (Figure 1c) shows an emission peak at around 510 nm (~2.43 eV). To determine the exciton binding energy and continuum transition bandgap in CsPbBr3 QDs, we performed a systematic analysis of the ultraviolet-visible (UV-vis) absorption spectrum at room temperature (Figure 1c), which exhibits a steep absorption edge followed by a plateau regime. The absorption spectrum was fitted using the well-known Elliott formula,50–52 with representative fitting results presented in Figure S1, and this analysis reveals distinct spectral contributions from both discrete excitonic states and continuum transitions. The fitting results yield a continuum transition bandgap (𝐸𝑔) of 2.496 eV and an exciton binding energy (𝐸𝑏) of 34 meV, and the associated excitonic transition displays a full width at half maximum (FWHM) of 88 meV, showing close consistency with reported values for CsPbBr3 quantum dots.1,53 Detailed spectral fitting method and corresponding fitting parameters are provided in the Simulation Section and Table S1 in the Supporting Information, respectively. In addition, the photoluminescence quantum yield (PLQY) of the colloidal QD solution was measured to be 45.1% under 365 nm excitation at an intensity of 0.12 mW/cm2 (see Figure S2).  6   Figure 1. Structural and optical characterization of CsPbBr3 QDs and schematic of the mixed-dimensional heterostructure. (a) TEM image of CsPbBr3 QDs displaying cubic morphology with an average size of 9.9 nm. The inset shows a high-resolution TEM image highlighting crystallinity. (b) Size distribution histogram of CsPbBr3 QDs derived from TEM, fitted with a Gaussian curve (red line). (c) UV-vis absorption (black) and PL (red) spectra of CsPbBr3 QDs in hexane at room temperature. (d) Schematic illustration of the 0D-2D-3D mixed-dimensional vdW heterostructure. The schematic in Figure 1d illustrates the configuration of our experimental 0D-2D-3D mixed-dimensional van der Waals (vdW) heterostructure. This structure consists of a 0D CsPbBr3  7 QD nanolayer positioned above a 3D gold (Au) nanoparticle film, with a mechanically exfoliated hBN layer acting as a 2D dielectric spacer to mitigate quenching effects. The fabrication process began with the deposition of a 60 nm thick Au film onto a 90 nm SiO2/Si substrate via thermal evaporation. Subsequently, multilayer hBN was exfoliated from bulk crystals onto a polydimethylsiloxane (PDMS) stamp and transferred onto the Au film. The thickness of the hBN layer was initially estimated using optical color contrast and later confirmed through atomic force microscopy (AFM) measurements. To form the CsPbBr3 QD nanolayer, we diluted the colloidal QD solution to an appropriate concentration and spin-coated 40 μL of the solution onto the pre-fabricated hBN-Au-SiO2/Si structure at 3000 rpm for 60 s. As a control, CsPbBr3 QDs were also spin-coated onto bare SiO2/Si substrates for comparison.  To validate the uniformity of the fabricated heterostructure samples presented in Figure 1d, we performed AFM measurements for a representative CsPbBr3 quantum dots-hBN-gold heterostructure, with the results presented in Figure S3. Figure S3a displays the topographic image of the heterostructure over a 50×50 μm² area. Figures S3b and S3c show 5×5 μm² magnified views of the quantum dots on 131 nm and 11 nm hBN layers, corresponding to the regions marked by Box 1 and Box 2 in Figure S3a, respectively. The distribution density of CsPbBr3 individual dots or small clusters is ~10/μm2 extracted from AFM measurements. These images demonstrate that, since the light spot diameter (exceeding 1 μm) in our optical measurements results in statistically averaged signals over a small area, the quantum dots within the optical measurement regime can be considered as being deposited on the hBN platform with relative uniformity in a dispersed manner. In addition, to evaluate the air stability of our spin-coated CsPbBr3 QD layers, we monitored the temporal evolution of PL spectra from the same area of the QD layer over 120 minutes of air  8 exposure, as presented in Figure S4. The results demonstrate a mere 4.4% reduction in PL intensity while maintaining invariant spectral line shape compared to the initial measurement, indicating robust moisture and oxygen stability of our QDs after removal from the hexane solution. Considering that subsequent photoluminescence and time-resolved photoluminescence characterization were conducted under ambient conditions, this observed stability confirms that the optical properties of the quantum dots remain effectively preserved without significant degradation throughout the experimental testing period. Optical Characterization and PL Enhancement Figure 2a presents the optical image of a representative heterostructure sample fabricated in our experiment. Due to their nanoscale dimensions, the CsPbBr3 QDs deposited on the surface are not visible under an optical microscope, as their size is below the diffraction-limited spatial resolution. However, in the corresponding atomic force microscopy (AFM) image (Figure 2b) of the same region as outlined in Figure 2a, the presence of CsPbBr3 QDs is clearly distinguishable on both the hBN and Au substrates. To investigate the surface plasmon-induced PL enhancement and its dynamics, we employed confocal scanning PL microscopy (405 nm, 10 W/cm2 excitation) and FLIM (375 nm, 10 W/cm2 excitation) on the same region, as shown in Figures 2c and 2d, respectively.55 In addition, we present another representative smaller-scale heterostructure in the Supporting Information, with corresponding optical, confocal scanning PL, and FLIM images displayed in Figure S5a, b, and c, respectively. This heterostructure consists of hBN with a thickness of approximately 20 nm and dimensions of ~80 μm×30 μm, thus allowing the complete architecture to be clearly and entirely visualized across all panels of Figure S5.  9  Figure 2. Optical characterization of a representative CsPbBr3-hBN-Au mixed-dimensional heterostructure. (a) Optical microscopy image of the heterostructure. (b) AFM image of the region outlined in (a). The inset shows a height profile. (c) Confocal scanning PL image of the same region as (a) under continuous 405 nm excitation at an intensity of 10 W/cm2. (d) FLIM image of the same region as (a) under pulsed 375 nm excitation at an intensity of 10 W/cm2. As illustrated in Figures 2c and 2d, the fluorescence intensity of CsPbBr3 QDs is significantly enhanced when placed on the hBN spacer, whereas it is notably suppressed on the Au substrate. Furthermore, the fluorescence lifetime map reveals that the PL lifetime of QDs varies significantly  10 across different substrates (Figure 2d), indicating the modulation of the PL lifetime by the heterostructure.  Figure 3a presents the PL spectra of CsPbBr3 QDs deposited on the hBN/Au heterostructure with varying hBN thicknesses, ranging from 5 to 100 nm. For comparison, Figure S6 displays the PL spectra of QDs on the optimized heterostructure (with 26 nm thick hBN) alongside those on a bare SiO2/Si substrate. The results indicate a substantial enhancement in PL intensity for QDs on hBN, with the emission peak centered around 518 nm. A slight variation in peak position is observed across different spectra, which we attribute to minor differences in QD size at different locations. To quantify the enhancement, we define the fluorescence enhancement factor, 𝑓 =𝐼0𝐼, where 𝐼 represents the PL intensity of CsPbBr3 QDs on the hBN/Au heterostructure, and 𝐼0 corresponds to the PL intensity of the same emitters on the SiO2/Si control substrate. We extracted the enhancement factor from confocal scanning PL measurements, averaging the PL intensities over regions with the same hBN thickness to minimize errors due to potential inhomogeneities in QD distribution. The extracted values of 𝑓𝑒𝑥𝑝, plotted in Figure 3b as a function of hBN thickness (black line), reveal a quenching effect when the QDs are in direct proximity to the Au film. As the hBN spacer thickness increases, the PL intensity gradually rises, reaching a peak enhancement factor of approximately 7 at an hBN thickness of ~26 nm. Beyond this point, 𝑓𝑒𝑥𝑝 decreases with further increases in hBN thickness, eventually dropping below 1 when the thickness exceeds 100 nm.    This trend aligns with previous reports, which suggest that emitters with inherently low quantum yields (e.g., monolayer MoS₂ with 𝜂 = 10−3 − 10−4) experience minimal quenching when placed near a metal film, reducing the necessity for a dielectric spacer.34 However, for  11 materials with relatively high quantum yields, such as the CsPbBr3 QDs used in this study (intrinsic PLQY of 45.1% under 365 nm, 0.12 mW/cm2 excitation), the nonradiative decay rate is a crucial factor, necessitating careful optimization of the emitter-metal spacing.23,34–36,56 The observed nonlinear dependence of PL enhancement on hBN thickness can be attributed to a combination of plasmon-induced enhancement of the incident electromagnetic field, an increased spontaneous emission rate due to the Purcell effect, and competing nonradiative processes, which will be discussed in detail later.  Figure 3. PL enhancement and simulation results for the mixed-dimensional heterostructure. (a) PL spectra of CsPbBr3 QDs on hBN/Au heterostructures with hBN thicknesses ranging from 5 to 100 nm under continuous 405 nm excitation at an intensity of 10 W/cm2. (b) PL enhancement factor as a function of hBN thickness: experimental data (black, 𝑓𝑒𝑥𝑝), total simulated enhancement (red, 𝑓𝑐𝑎𝑙), simulated excitation component (green, 𝑓𝑐𝑎𝑙𝑒𝑥), and simulated emission component  12 (blue, 𝑓𝑐𝑎𝑙𝑒𝑚). Error bars represent statistical variation derived from scanning PL measurements. (c) Differential reflection spectrum of the Au nanoparticle film. (d) Simulated cross-sectional view of the local electric field amplitude |𝑬| distribution across the heterostructure at an excitation wavelength of 405 nm and an hBN thickness of 26 nm. (e) Line profile of the electric field |𝑬| at different positions in the heterostructure along the black arrow marked in (d). To verify the role of surface plasmons in modulating the PL properties of the heterostructure, we conducted differential reflectance microscopy ( 𝛥𝑅/𝑅 ) measurements of the 60 nm Au nanoparticle film deposited on a SiO2/Si substrate (Figure 3c). The results indicate a broad plasmonic resonance absorption peak centered at 568 nm, which overlaps significantly with the PL emission of CsPbBr3 QDs (Figure 3a). This spectral overlap suggests an efficient interaction between excitons in the QDs and surface plasmons in the Au film, facilitating the observed PL enhancement. To analyze the PL enhancement, we model CsPbBr3 QDs as randomly oriented electric dipoles under the statistical assumption, and decompose the surface plasmon contributions into two components: excitation rate enhancement at the incident wavelength and quantum yield enhancement at the emission wavelength. Accordingly, the PL enhancement factor 𝑓𝑐𝑎𝑙  is expressed as:  𝑓𝑐𝑎𝑙 =𝛾𝑒𝑥′𝛾𝑒𝑥∙𝛾𝑒𝑚′𝛾𝑒𝑚= 𝑓𝑐𝑎𝑙𝑒𝑥 ∙ 𝑓𝑐𝑎𝑙𝑒𝑚 (1) where 𝛾𝑒𝑥 and 𝛾𝑒𝑚 represent the excitation rate at the incident wavelength and the spontaneous emission rate at the emission wavelength, respectively. The primed terms denote these values in the presence of the Au film. Surface plasmons concentrate incident light into a localized region near the Au film, thereby enhancing the local electromagnetic field. This leads to an increase in the absorption cross-section  13 and subsequently raises the excitation rate 𝛾𝑒𝑥′ for the excitonic system of CsPbBr3 QDs. Since the exciton orientation of CsPbBr3 QDs dispersed on the substrate is isotropically distributed, the excitation rate enhancement is proportional to the squared local electric field magnitude, |𝑬|2. To examine this effect, we performed a numerical simulation for the local electric field distribution at an excitation wavelength of 405 nm and an hBN thickness of 26 nm (Figure 3d), based on the finite element method (FEM) (see Supporting Information for details). The simulation was conducted when 𝑓𝑒𝑥𝑝  reaches its maximum value. The simulation results reveal a substantial enhancement of the localized electromagnetic field at the QD position, leading to increased absorption of incident light. Figure 3e illustrates the spatial distribution of |𝑬| at different positions in the heterostructure along the black arrow marked in Figure 3d.  Specifically, for plasmon-induced localized field enhancement in our heterostructure, the mechanism can essentially be interpreted as an optical interference process primarily involving the conductive Au layer, intrinsic hBN spacer, and semiconductor QD layer. The adjustment of hBN thickness effectively modulates the interference conditions to maximize the incident electric field intensity at the QD layer. For comparative analysis, Figure S7 displays the simulated local electric field amplitude |𝑬| distribution across the optimized heterostructure (with 26 nm thick hBN) alongside those on a bare SiO2/Si substrate. The functionality of the mixed-dimensional heterostructure is clearly demonstrated in this figure, where incident light excites surface plasmons that subsequently become concentrated near the QD layer. This concentration induces significant electromagnetic field amplification in the target region, thereby enhancing QD absorption. In stark contrast, this plasmon-induced enhancement effect is nearly absent in the bare SiO2/Si substrate configuration. For reference, we also compared the PL spectra of CsPbBr3 QDs spin-coated on different substrates including hBN/Au heterostructures, hBN/SiO2/Si, SiO2/Si, and quartz, as  14 shown in Figure S8. Additionally, the confocal PL scanning images of QDs on hBN/SiO2/Si, SiO2/Si, and quartz substrates are presented in Figure S9. The measurements in Figure S8 reveal distinct PL intensity variations among different insulating substrates, which can be attributed to substrate-dependent optical interference effects. For QDs on the hBN/Au heterostructure, they not only experience local field enhancement through the optical interference process involving the conductive Au layer, but also exhibit enhanced spontaneous emission rates via the Purcell effect, which is absent in other insulating substrates. Thus, the PL intensity of QDs on the hBN/Au heterostructure is significantly higher than that on other substrates. Furthermore, to quantitatively determine the excitation component of the PL enhancement factor, we implemented a parametric scanning approach in the FEM simulation. This methodology simulated the electric field amplitude (denoted as |𝑬′|) at the QD layer position across varying hBN thicknesses from 0 to 100 nm. These values were compared against the reference electric field amplitude (denoted as |𝑬|) at the QD layer position in the SiO2/Si substrate system. The excitation enhancement factor was then calculated as 𝑓𝑐𝑎𝑙𝑒𝑥 =𝛾𝑒𝑥′𝛾𝑒𝑥=|𝑬′|2|𝑬|2 , with the computational results plotted as the green line in Figure 3b.  In terms of quantum yield enhancement, the radiative transition rate 𝛾 is governed by Fermi’s golden rule: 𝛾 =2𝜋ℏ2 |〈𝑓|𝑝̂ ∙ 𝑬̂𝑣𝑎𝑐|𝑖〉|2𝜌(𝜔). Here, 𝛾 represents the transition decay rate from the excited state |𝑖⟩ to the final state |𝑓⟩, 𝑝̂ and 𝑬̂𝑣𝑎𝑐 are the electric dipole and vacuum-field operators at the emitter’s position, and 𝜌(𝜔) denotes the local photonic density of states.32 Given the highly confined nature of the plasmonic field, the local photonic density of states is significantly enhanced, leading to an increase in the spontaneous emission rate. To quantitatively analyze the Purcell effect in this system, we employed a semiclassical method previously reported in the literature.31,56 In our model, QD emitters are treated as an ensemble of randomly oriented oscillating dipoles  15 positioned at the top of the hBN layer. Using the dyadic Green’s function approach for a dipole above a layered interface, we calculated the enhancement in the spontaneous emission rate due to the Purcell effect. Further details on these calculations can be found in the Simulation Section of the Supporting Information. The emission component of the PL enhancement factor, calculated as 𝑓𝑐𝑎𝑙𝑒𝑚 =𝛾𝑒𝑚′𝛾𝑒𝑚, is plotted in Figure 3b as the blue line.  The red line in Figure 3b represents the total calculated PL enhancement factor, 𝑓𝑐𝑎𝑙 =𝑓𝑐𝑎𝑙𝑒𝑥 ∙ 𝑓𝑐𝑎𝑙𝑒𝑚, demonstrating excellent agreement with the experimental data. This confirms that the observed enhancement results from the combined contributions of the localized electromagnetic field enhancement at the excitation wavelength and the Purcell effect at the emission wavelength. It is important to note that, in our simulations, the Au nanoparticle film was approximated as a planar metallic film for both excitation and emission enhancement calculations. This assumption neglects potential contributions from interparticle hotspots, where localized plasmonic effects could further enhance the incident field.32,34 The slight deviations between experimental data and simulation results in Figure 3b may stem from this simplification. PL Decay Dynamics and Mechanistic Insights We employed Jablonski diagrams (Figure 4a and 4b) to elucidate the Metal-enhanced PL mechanism.4,20 In the case of perovskite QDs in free space under optical excitation (Figure 4a), the excitonic system transitions from the ground state (S0) to higher excited states (S1, S2 etc.) upon absorbing incident light, with an excitation rate denoted as 𝛾𝑒𝑥. After undergoing internal conversion, which leads to relaxation to lower vibrational states, the system transitions back to the ground state, resulting in either radiative decay (Γ QDs) via spontaneous emission or nonradiative decay rate (knrQDs). When the perovskite QDs are placed near the Au nanoparticle film (Figure 4b), both excitation and emission rates are significantly altered due to strong exciton-plasmon  16 coupling. Upon illumination, surface plasmons are excited at the metal-dielectric interface, enhancing the local electromagnetic field and thereby increasing the excitation rate 𝛾𝑒𝑥pl . Additionally, new decay channels emerge as excitons couple to surface plasmons, leading to an enhanced decay rate (ΓcQDs) due to energy transfer into surface plasmon modes. Concurrently, nonradiative quenching (kqQDs) becomes relevant, which is induced by the presence of metal through nonradiative energy dissipation. The energy transferred to surface plasmons modes can either be radiatively emitted (Γ pl) or lost through nonradiative decay (knrpl). The quantum yield (𝜂0) and PL lifetime (𝜏0) of perovskite QDs in free space can be expressed as: 𝜂0 = Γ QDs𝜏0 (2) 𝜏0 = 1Γ QDs + knrQDs(3) However, in the presence of the plasmonic system, both parameters are modified due to the Purcell effect, and the modified quantum yield (𝜂) and PL lifetime (𝜏) are given by:  𝜂 = (Γ QDs + Γ pl)𝜏 (4) 𝜏 =1Γ QDs + Γ pl + knrQDs + kqQDs + knrpl(5) By carefully tuning the thickness of the hBN dielectric spacer, we can optimize the radiative decay rate (Γ QDs + Γ pl) while minimizing nonradiative losses (knrQDs + kqQDs + knrpl). This adjustment helps reduce quenching effects while maintaining efficient exciton-plasmon coupling. Specifically, hBN serves to hinder direct charge transfer from CsPbBr3 quantum dots to the Au nanoparticle film and suppresses nonradiative relaxation processes. In this regard, its function parallels that of conventional dielectric spacers such as SiO2,4,56 Al2O3,57–59 or polymers (e.g., PE or PMMA),23,60 which have been extensively utilized in previous studies of plasmonic systems.  17  Figure 4. Energy diagrams and PL decay dynamics. Jablonski diagrams illustrating the energy transfer pathways when perovskite quantum dots are (a) in free space and (b) near Au nanoparticle films. S1 : Excited state, S0: Ground state, 𝛾𝑒𝑥 : Excitation rate by absorption of incident light, 𝑘nrQDs: Intrinsic nonradiative decay rate of QDs, 𝛤QDs: Intrinsic radiative decay rate of QDs, 𝛾𝑒𝑥pl: Metal-enhanced excitation rate, 𝑘qQDs: Nonradiative quenching of QDs by Au, 𝛤cQDs: Enhanced decay rate of QDs by energy conversion into surface plasmon mode, 𝛤pl: Radiative decay rate of plasmon, knrpl: Nonradiative decay rate of plasmon. (c) TRPL curves of CsPbBr3 QDs on hBN/Au heterostructures with varying hBN thicknesses under pulsed 375 nm excitation at an intensity of 10 W/cm2, fitted with biexponential decays (solid black lines). (d) Average PL lifetime as a function of hBN thickness, compared to SiO2/Si substrate. The error bars reflect fitting uncertainty. To experimentally examine the influence of surface plasmons on the decay dynamics of CsPbBr3 QDs, we employed FLIM to measure the PL lifetime of QDs on both the hBN/Au  18 heterostructure and bare SiO2/Si substrates (Figure 2d). The time-resolved PL (TRPL) curves extracted from FLIM measurements, shown in Figure 4c, provide a quantitative assessment of the PL lifetime as a function of hBN thickness. For heterostructures with 0 nm and 101 nm hBN thickness, the TRPL curves are not displayed due to insufficient photon counts, likely caused by severe plasmon-induced quenching. A direct comparison of TRPL results for CsPbBr3 QDs on the optimized heterostructure (26 nm hBN/Au) and on the bare SiO2/Si substrate is provided in Figure S10 in the Supporting Information. The PL lifetime of QDs on the heterostructure ( 𝜏 ) is significantly shorter than that on the SiO2/Si substrate (𝜏0), confirming that the presence of the Au film modifies the emission dynamics, as predicted by the PL lifetime modification equations. All the TRPL curves in Figure 4c were well fitted using a bi-exponential function, 𝐼(𝑡) =𝐴1 exp(− 𝑡 𝜏1⁄ ) + 𝐴2 exp(− 𝑡 𝜏2⁄ ). From these fits, the average PL lifetime (𝜏̅) was calculated as 𝜏̅ = (𝐴1𝜏12 + 𝐴2𝜏22) (𝐴1𝜏1 + 𝐴2𝜏2)⁄  of QDs. The results, plotted in Figure 4d, demonstrate that the average lifetime of CsPbBr3 QDs on the bare SiO2/Si substrate is 𝜏̅0 = 4.79 ns. For QDs on the heterostructure, the average lifetimes vary with hBN thickness, yielding values of 2.20, 2.17, 1.95, 2.40, 2.28, and 2.52 ns for hBN thicknesses of 5, 16, 26, 33, 42, and 64 nm, respectively. The corresponding fitting parameters, including decay constants (𝜏1, 𝜏2), amplitude ratios (𝐴1, 𝐴2), and calculated average lifetimes (𝜏̅), are tabulated in Table S3 in the Supporting Information. The observed trend directly correlates with the PL enhancement behavior as a function of hBN thickness: the PL lifetime initially decreases, reaching a minimum at ~26 nm hBN, which coincides with the maximum PL enhancement factor of 7-fold. Beyond this optimal thickness, the PL lifetime gradually increases, mirroring the decline in PL enhancement. This correlation suggests that stronger PL enhancement is generally associated with shorter PL lifetimes, confirming that an appropriate hBN thickness optimizes exciton-plasmon interactions. At ~26 nm  19 hBN, the increase in radiative decay rate (Γ pl ) is sufficient to counteract the concurrent increase in nonradiative decay channels (kqQDs + knrpl) caused by exciton-plasmon coupling. In addition, the CsPbBr3 QDs always exhibit shorter PL lifetimes when directly placed on Au films (0 nm hBN thickness) or Au-hBN heterostructures compared to the bare SiO2/Si control substrate. This reduction can be attributed to the introduction of additional radiative (Γ pl) and nonradiative decay channels kqQDs + knrpl) arising from the Au nanoparticle film, which collectively accelerate the depopulation of excited states and consequently diminish the PL lifetime (𝜏̅) of the quantum dots. For reference, we also compared the time-resolved PL spectra of CsPbBr3 QDs spin-coated on different substrates including hBN/Au heterostructures, hBN/SiO2/Si, SiO2/Si, and quartz, as shown in Figure S11. The measurement results demonstrate that the QD lifetimes on insulating substrates (hBN/SiO2/Si, SiO2/Si, and quartz) show no significant differences, while the lifetime on hBN/Au heterostructures is substantially lower than those on all insulating substrates, which aligns with our aforementioned discussion results. To comparatively investigate whether the excitation fluence of incident light affects the PL enhancement factor, we also conducted parallel measurements of PL and TRPL for CsPbBr3 QDs on hBN/Au and SiO2/Si substrates under varying incident light fluences. Figure S12 presents the PL intensity and average lifetime of QDs as functions of laser power density under continuous 405 nm excitation and pulsed 375 nm excitation, respectively. Experimental results demonstrated that within the laser power density range of 4-15 W/cm2, both the PL enhancement factor and average lifetime of QDs on both substrates exhibited no discernible regular trends, suggesting that no significant changes in exciton dynamics occurred within this power density range. This observation validates the reliability of employing 10 W/cm2 excitation power density for analyzing PL enhancement and lifetime characteristics throughout our experimental investigations.  20 CONCLUSIONS In summary, we demonstrated a 0D-2D-3D mixed-dimensional van der Waals heterostructure that significantly enhances the photoluminescence of CsPbBr3 perovskite quantum dots through plasmon-induced field amplification and the Purcell effect. By optimizing the hBN dielectric spacer thickness (~26 nm), we achieved a seven-fold enhancement in PL intensity while reducing the PL lifetime, confirming increased radiative decay. Theoretical modeling and numerical simulations validated the experimental findings, attributing the enhancement to localized electromagnetic field enhancement and modified spontaneous emission rates. In future applications, the plasmonic system enhances the internal quantum efficiency of perovskite QDs, thereby enabling direct improvement in the performance of perovskite quantum dot light-emitting diodes. Concurrently, incident photons excite plasmon modes that concentrate electromagnetic fields near the perovskite QD layer, thereby boosting light absorption in QDs—a critical advantage for enhancing the efficiency of photodetectors and phototransistors. Our work provides valuable insights into exciton-plasmon coupling mechanisms in hybrid perovskite-plasmonic systems, establishing a design framework for high-efficiency quantum photonic devices through metal-enhanced photoluminescence. EXPERIMENTAL SECTION Materials. All chemical reagents, including hexane (anhydrous HEX, Sigma-Aldrich, 98%), ethyl acetate (EA, Sigma-Aldrich, 90%), PbBr2 (Sigma-Aldrich, 99.99%), Cs2CO3 (Sigma-Aldrich, 99.99%), octadecene (Sigma-Aldrich, ODE, 90%), oleylamine (OAm, Aladdin, 90%), and oleic acid (OA, Sigma-Aldrich, 90%), were used as purchased without further purification. Fabrication of colloidal CsPbBr3 quantum dots (QDs). For the preparation of the Cs-OA precursor, a 25-mL three-necked flask was charged with Cs2CO3 (0.407 g), OA (1.25 mL), and  21 ODE (20 mL). The mixture was then degassed under vacuum at 120 °C for 1 hour and heated to 150 °C under an Ar atmosphere until the reaction between the OA and Cs2CO3 was completed.  For the synthesis of CsPbBr3 QDs, PbBr2 (0.138 g) and ODE (10 mL) were introduced into a 25-mL three-necked flask. The mixture was heated at 120°C for 1 hour under vacuum, followed by the introduction of argon into the flask. Subsequently, pre-dried OAm (1 mL) and OA (1 mL) were added to the mixture. The reaction flask was then heated to 160°C until the solution turned clear. Preheated cesium oleate (0.8 mL) was rapidly injected into the flask. After a reaction time of 5 seconds, the flask was cooled to room temperature using ice water. For the isolation and purification, the crude solution of CsPbBr3 QDs was poured into a centrifuge tube and centrifuged at 10,000 rpm for 10 minutes. The precipitate was redispersed in 4 mL of n-hexane, mixed with 8 mL of ethyl acetate, and then centrifuged again at 10,000 rpm for 5 minutes. The final precipitate was distributed in 2 mL of n-hexane. Fabrication of CsPbBr3 QDs, hBN and gold film mixed-dimensional van der Waals (vdW) heterostructure. The 60 nm gold film was deposited by thermal evaporation onto the top of a 90 nm SiO2/Si substrate under nitrogen atmosphere. Multilayer hBN flakes were first mechanically exfoliated onto PDMS (Gel-pak, PF-40/17-X4) from a high-quality hBN bulk crystal using Scotch tape, and then transferred onto the Au film. The CsPbBr3 quantum dot film was fabricated by spin-coating 40 μl of the diluted QD colloidal solution onto the top of the as-fabricated hBN-Au-SiO2/Si structure at 3000 rpm for 60 seconds. Characterizations. The TEM images were obtained at an accelerating voltage of 200 kV using a JEOL JEM-2100F transmission electron microscope. For TEM sample preparation, the CsPbBr3 quantum dots were first dispersed in n-hexane solution and subjected to ultrasonication at 60 Hz. Subsequently, several drops of the well-dispersed suspension were drop-cast onto a  22 copper grid and allowed to air-dry completely prior to imaging. To minimize potential electron beam-induced damage to the quantum dot crystal structure, the imaging duration for each selected region was limited to under 10 minutes throughout all imaging sessions. The UV-vis absorption measurements were conducted under ambient conditions using a tungsten halogen lamp (HL10000-Mini, Oceanhood) as the excitation light source. The sample (quantum dot colloidal solution, approximately 3 mL) was placed in a standard 12.5×12.5×45 mm quartz cuvette with a 10 mm optical path length. The transmitted light was coupled into a fiber optic spectrometer (XS11639, Oceanhood) through an SMA905 optical fiber to obtain the absorption spectrum. The AFM measurements were conducted under ambient conditions using a Bruker Innova instrument. The surface topography measurements were operated in tapping mode with metallic AFM probes (MikroMasch, HQ:NSC15/Cr-Au).  The confocal PL mapping was carried out under ambient conditions using a scanning confocal fluorescence microscope (Horiba, XploRA PLUS). A 405 nm solid-state laser was used as the excitation source and focused on the samples through a 20× objective lens (N.A. = 0.40). The system was equipped with a 150 grooves/mm holographic grating and a confocal attachment, and the PL emission was detected using a Peltier-cooled electron multiplying CCD (SIN-EM FIVIS).  The FLIM measurements were performed under ambient conditions using a PicoQuant MicroTime200 system integrated with an Olympus microscope. A 375 nm pulsed laser, operating at a 20 MHz repetition rate, was used as the excitation source. The incident laser intensity was controlled using a variable neutral density filter (Lbtek, NDFR-50S-3M), and then passed through a 500 nm shortpass filter (Jcoptix, OFE1SP-500) and a 375 nm dichroic beam splitter, and finally focused onto the sample surface using an objective lens (Olympus MPLFLN20×, N.A. = 0.40).  23 The emitted PL signal from the sample was collected by the same objective, passed through the dichroic beam splitter and a 405 nm long pass filter, followed by a second variable neutral density filter, a 300 nm confocal pinhole, and finally detected by a single-photon avalanche diode (SPAD). The electrical signals were processed using time-correlated single-photon counting (TCSPC) electronics (PicoQuant, TimeHarp 260). In the presented FLIM images, the PL intensity and PL lifetime are both derived from the signals collected by the single-photon detector at the same excitation spot. Specifically, the PL intensity reveals the counts of photons collected, which affects the brightness of the image, labeled as a gray scale, and the PL lifetime reveals the intensity weighted average lifetime, which affects the pseudocolor of the image, labeled as a rainbow scale. The differential reflectance spectra (𝛥𝑅/𝑅) were acquired under ambient conditions using a spectrometer system (EasySpec, Metatest corporation) equipped with a halogen lamp. To obtain the 𝛥𝑅/𝑅  spectra, we measured the reflectance spectra of the sample (Au nanoparticle film), denoted as 𝐼𝑠𝑎𝑚𝑝𝑙𝑒, and the corresponding bare SiO2/Si substrate (uncoated region), denoted as 𝐼𝑠𝑢𝑏𝑠𝑡𝑟𝑎𝑡𝑒 . The differential reflectance spectra were then defined as 𝛥𝑅/𝑅 =(𝐼𝑠𝑎𝑚𝑝𝑙𝑒 − 𝐼𝑠𝑢𝑏𝑠𝑡𝑟𝑎𝑡𝑒) 𝐼𝑠𝑢𝑏𝑠𝑡𝑟𝑎𝑡𝑒⁄ . The PLQY measurements were carried out under ambient conditions using Edinburgh Instruments Spectrofluorometer FS5. The excitation source employed was a xenon lamp operating at 365 nm wavelength with an irradiation intensity of 0.12 mW/cm2. The measurement of incident light power density was performed using a power meter (Thorlabs, PM100D) equipped with a microscope slide power meter photodiode sensor head (Thorlabs, S170C). The incident power was first measured in a dark environment, and subsequently the light spot diameter was determined through microscopic measurements, enabling the calculation of the power density.  24 ASSOCIATED CONTENT Data Availability Statement Data underlying the results presented in this paper are not publicly available at this time but maybe obtained from the authors upon reasonable request. Supporting Information The Supporting Information is available free of charge. Detailed description of experimental and simulation section; supplementary results of PLQY, PL, TRPL AUTHOR INFORMATION Corresponding Authors Minliang Lai − School of Nano Science and Technology, Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu 215123, China; Email: mllai@ustc.edu.cn Jia Lin − Department of Physics, Shanghai University of Electric Power, Shanghai 200090, China; Email: jlin@shiep.edu.cn Sheng Wang − Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, China; Wuhan Institute of Quantum Technology, Wuhan, Hubei 430206, China; orcid.org/0000-0001-7923-478X; Email: shengwang16@whu.edu.cn  25 Author Contributions §K.Z., J.Z. and R.M. contributed equally to this work. S.W. conceived, designed, and supervised the research. K.Z. fabricated the mixed-dimensional heterostructure, conducted the PL, absorption and differential reflection measurements as well as performed the simulation. W.Z. and Z.X. conducted the AFM measurement. J.Z. and S.C. conducted the FLIM measurements. R.M., Y.Zhou and M.Li. prepared the colloidal solution of CsPbBr3 QDs and conducted the TEM measurements under the supervision of Y.W. and J.L.. Y.Zhao conducted the PLQY measurements under the supervision of M.Lai. K.W. and T.T. provided the h-BN crystals. K.Z. and S.W. analyzed the data and wrote the manuscript.  Notes The authors declare no competing financial interest. ACKNOWLEDGEMENTS This work was supported by the Wuhan Natural Science Foundation (grant no. 2024040801020219), the National Natural Science Foundation of China (grant no. 12374357), and the Fundamental Research Funds for the Central Universities. K.W. and T.T. acknowledge support from the JSPS KAKENHI (grant no. 21H05233 and 23H02052), the CREST (JPMJCR24A5), JST and World Premier International Research Center Initiative (WPI), MEXT, Japan.   26 REFERENCES (1) Protesescu, L.; Yakunin, S.; Bodnarchuk, M. I.; Krieg, F.; Caputo, R.; Hendon, C. H.; Yang, R. X.; Walsh, A.; Kovalenko, M. V. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut. Nano Lett. 2015, 15 (6), 3692–3696. (2) Shi, Z.; Li, Y.; Zhang, Y.; Chen, Y.; Li, X.; Wu, D.; Xu, T.; Shan, C.; Du, G. High-Efficiency and Air-Stable Perovskite Quantum Dots Light-Emitting Diodes with an All-Inorganic Heterostructure. Nano Lett. 2017, 17 (1), 313–321. (3) Zhou, X.; Zhai, L.; Liu, J. Epitaxial Quantum Dots: A Semiconductor Launchpad for Photonic Quantum Technologies. Photon. Insights 2022, 1 (2), R07. (4) Zhao, W.; Wen, Z.; Xu, Q.; Zhou, Z.; Li, S.; Fang, S.; Chen, T.; Sun, L.; Wang, X.; Liu, Y.; Sun, Y.; Tan, Y.-W.; Dai, N.; Hao, J. Remarkable Photoluminescence Enhancement of CsPbBr3 Perovskite Quantum Dots Assisted by Metallic Thin Films. Nanophotonics 2021, 10 (8), 2257–2264. (5) Tiguntseva, E.; Koshelev, K.; Furasova, A.; Tonkaev, P.; Mikhailovskii, V.; Ushakova, E. V.; Baranov, D. G.; Shegai, T.; Zakhidov, A. A.; Kivshar, Y.; Makarov, S. V. Room-Temperature Lasing from Mie-Resonant Nonplasmonic Nanoparticles. ACS Nano 2020, 14 (7), 8149–8156. (6) Aqoma, H.; Lee, S.-H.; Imran, I. F.; Hwang, J.-H.; Lee, S.-H.; Jang, S.-Y. Alkyl Ammonium Iodide-Based Ligand Exchange Strategy for High-Efficiency Organic-Cation Perovskite Quantum Dot Solar Cells. Nat Energy 2024, 9 (3), 324–332.  27 (7) Zhu, C.; Boehme, S. C.; Feld, L. G.; Moskalenko, A.; Dirin, D. N.; Mahrt, R. F.; Stöferle, T.; Bodnarchuk, M. I.; Efros, A. L.; Sercel, P. C.; Kovalenko, M. V.; Rainò, G. Single-Photon Superradiance in Individual Caesium Lead Halide Quantum Dots. Nature 2024, 626 (7999), 535–541. (8) Stranks, S. D.; Eperon, G. E.; Grancini, G.; Menelaou, C.; Alcocer, M. J. P.; Leijtens, T.; Herz, L. M.; Petrozza, A.; Snaith, H. J. Electron-Hole Diffusion Lengths Exceeding 1 Micrometer in an Organometal Trihalide Perovskite Absorber. Science 2013, 342 (6156), 341–344. (9) Baek, S.; Yang, S. J.; Yang, H.; Shao, W.; Yang, Y.; Dou, L. Exciton Dynamics in Layered Halide Perovskite Light‐Emitting Diodes. Adv. Mater. 2024, 2411998. (10) Jiang, J.; Xiong, M.; Fan, K.; Bao, C.; Xin, D.; Pan, Z.; Fei, L.; Huang, H.; Zhou, L.; Yao, K.; Zheng, X.; Shen, L.; Gao, F. Synergistic Strain Engineering of Perovskite Single Crystals for Highly Stable and Sensitive X-Ray Detectors with Low-Bias Imaging and Monitoring. Nat. Photon. 2022, 16 (8), 575–581. (11) Mei, A.; Peng, X.; Li, X.; Zhang, G.; Lin, S.; Fu, N. Anions Regulation of 1D Perovskite Intrusion-Behavior for Efficient and Stable Perovskite Solar Cells. ACS Appl. Mater. Interfaces 2024, 16 (24), 31209–31217. (12) Ling, Y.; Tian, Y.; Wang, X.; Wang, J. C.; Knox, J. M.; Perez‐Orive, F.; Du, Y.; Tan, L.; Hanson, K.; Ma, B.; Gao, H. Enhanced Optical and Electrical Properties of Polymer‐Assisted All‐Inorganic Perovskites for Light‐Emitting Diodes. Adv. Mater. 2016, 28 (40), 8983–8989.  28 (13) Shan, Q.; Dong, Y.; Xiang, H.; Yan, D.; Hu, T.; Yuan, B.; Zhu, H.; Wang, Y.; Zeng, H. Perovskite Quantum Dots for the Next‐Generation Displays: Progress and Prospect. Adv. Funct. Mater. 2024, 34 (36), 2401284. (14) Hao, M.; Ding, S.; Gaznaghi, S.; Cheng, H.; Wang, L. Perovskite Quantum Dot Solar Cells: Current Status and Future Outlook. ACS Energy Lett. 2024, 9 (1), 308–322. (15) Gao, L.; Zhang, Y.; Gou, L.; Wang, Q.; Wang, M.; Zheng, W.; Wang, Y.; Yip, H.-L.; Zhang, J. High Efficiency Pure Blue Perovskite Quantum Dot Light-Emitting Diodes Based on Formamidinium Manipulating Carrier Dynamics and Electron State Filling. Light Sci Appl 2022, 11 (1), 346. (16) Chen, J.; Jia, D.; Zhuang, R.; Hua, Y.; Zhang, X. Rejuvenating Aged Perovskite Quantum Dots for Efficient Solar Cells. Adv. Mater. 2024, 36 (1), 2306854. (17) Bu, T.; Li, J.; Li, H.; Tian, C.; Su, J.; Tong, G.; Ono, L. K.; Wang, C.; Lin, Z.; Chai, N.; Zhang, X.-L.; Chang, J.; Lu, J.; Zhong, J.; Huang, W.; Qi, Y.; Cheng, Y.-B.; Huang, F. Lead Halide–Templated Crystallization of Methylamine-Free Perovskite for Efficient Photovoltaic Modules. Science 2021, 372 (6548), 1327–1332. (18) Chen, W.; Hao, J.; Hu, W.; Zang, Z.; Tang, X.; Fang, L.; Niu, T.; Zhou, M. Enhanced Stability and Tunable Photoluminescence in Perovskite CsPbX3/ZnS Quantum Dot Heterostructure. Small 2017, 13 (21), 1604085. (19) Quan, L. N.; Yuan, M.; Comin, R.; Voznyy, O.; Beauregard, E. M.; Hoogland, S.; Buin, A.; Kirmani, A. R.; Zhao, K.; Amassian, A.; Kim, D. H.; Sargent, E. H. Ligand-Stabilized Reduced-Dimensionality Perovskites. J. Am. Chem. Soc. 2016, 138 (8), 2649–2655.  29 (20) Fothergill, S. M.; Joyce, C.; Xie, F. Metal Enhanced Fluorescence Biosensing: From Ultra-Violet towards Second near-Infrared Window. Nanoscale 2018, 10 (45), 20914–20929. (21) Zhang, X.; Hu, H.; Qie, Y.; Lin, L.; Guo, T.; Li, F. Boosting the Efficiency of High-Resolution Quantum Dot Light-Emitting Devices Based on Localized Surface Plasmon Resonance. ACS Appl. Mater. Interfaces 2024, 16 (10), 13219–13224. (22) Luo, J.; Wu, Q.; Zhou, L.; Lu, W.; Yang, W.; Zhu, J. Plasmon-Induced Hot Carrier Dynamics and Utilization. Photon. Insights 2023, 2 (4), R08. (23) Song, M.; Wu, B.; Chen, G.; Liu, Y.; Ci, X.; Wu, E.; Zeng, H. Photoluminescence Plasmonic Enhancement of Single Quantum Dots Coupled to Gold Microplates. J. Phys. Chem. C 2014, 118 (16), 8514–8520. (24) Linic, S.; Aslam, U.; Boerigter, C.; Morabito, M. Photochemical Transformations on Plasmonic Metal Nanoparticles. Nat. Mater. 2015, 14 (6), 567–576. (25) Linic, S.; Christopher, P.; Ingram, D. B. Plasmonic-Metal Nanostructures for Efficient Conversion of Solar to Chemical Energy. Nat. Mater. 2011, 10 (12), 911–921. (26) Krivenkov, V.; Samokhvalov, P.; Nabiev, I.; Rakovich, Y. P. Synergy of Excitation Enhancement and the Purcell Effect for Strong Photoluminescence Enhancement in a Thin-Film Hybrid Structure Based on Quantum Dots and Plasmon Nanoparticles. J. Phys. Chem. Lett. 2020, 11 (19), 8018–8025. (27) Huang, X.; Li, H.; Zhang, C.; Tan, S.; Chen, Z.; Chen, L.; Lu, Z.; Wang, X.; Xiao, M. Efficient Plasmon-Hot Electron Conversion in Ag–CsPbBr3 Hybrid Nanocrystals. Nat Commun 2019, 10 (1), 1163.  30 (28) Leng, H.; Szychowski, B.; Daniel, M.-C.; Pelton, M. Strong Coupling and Induced Transparency at Room Temperature with Single Quantum Dots and Gap Plasmons. Nat Commun 2018, 9 (1), 4012. (29) Bai, G.; Tsang, M.; Hao, J. Tuning the Luminescence of Phosphors: Beyond Conventional Chemical Method. Adv. Optical Mater. 2015, 3 (4), 431–462. (30) Maier, S. A. Plasmonics: Fundamentals and Applications; Springer, 2007. (31) Novotny, L.; Hecht, B. Principles of Nano-Optics; Cambridge University Press, 2012. (32) Giannini, V.; Fernández-Domínguez, A. I.; Heck, S. C.; Maier, S. A. Plasmonic Nanoantennas: Fundamentals and Their Use in Controlling the Radiative Properties of Nanoemitters. Chem. Rev. 2011, 111 (6), 3888–3912. (33) Su, Q.; Jiang, C.; Gou, D.; Long, Y. Surface Plasmon-Assisted Fluorescence Enhancing and Quenching: From Theory to Application. ACS Appl. Bio Mater. 2021, 4 (6), 4684–4705. (34) Zhao, W.; Wang, S.; Liu, B.; Verzhbitskiy, I.; Li, S.; Giustiniano, F.; Kozawa, D.; Loh, K. P.; Matsuda, K.; Okamoto, K.; Oulton, R. F.; Eda, G. Exciton–Plasmon Coupling and Electromagnetically Induced Transparency in Monolayer Semiconductors Hybridized with Ag Nanoparticles. Adv. Mater. 2016, 28 (14), 2709–2715. (35) Nayak, C.; Masanta, S.; Monga, S.; Paul, S.; Bera, S.; Mondal, S.; Bhattacharya, S.; Singha, A. Tailoring Photoluminescence in MoSSe Alloys through Gold Nanostructure Coupling: Influence of Midgap States and Localized Surface-Plasmon Resonance. Phys. Rev. B 2024, 109 (12), 125306.  31 (36) Lee, Y.; Forte, J. D. S.; Chaves, A.; Kumar, A.; Tran, T. T.; Kim, Y.; Roy, S.; Taniguchi, T.; Watanabe, K.; Chernikov, A.; Jang, J. I.; Low, T.; Kim, J. Boosting Quantum Yields in Two-Dimensional Semiconductors via Proximal Metal Plates. Nat Commun 2021, 12 (1), 7095. (37) Andrew, P.; Barnes, W. L. Energy Transfer Across a Metal Film Mediated by Surface Plasmon Polaritons. Science 2004, 306 (5698), 1002–1005. (38) Najmaei, S.; Mlayah, A.; Arbouet, A.; Girard, C.; Léotin, J.; Lou, J. Plasmonic Pumping of Excitonic Photoluminescence in Hybrid MoS2–Au Nanostructures. ACS Nano 2014, 8 (12), 12682–12689. (39) Qi, X.; Lo, T. W.; Liu, D.; Feng, L.; Chen, Y.; Wu, Y.; Ren, H.; Guo, G.-C.; Lei, D.; Ren, X. Effects of Gap Thickness and Emitter Location on the Photoluminescence Enhancement of Monolayer MoS2 in a Plasmonic Nanoparticle-Film Coupled System. Nanophotonics 2020, 9 (7), 2097–2105. (40) Huang, S.; Wang, C.; Xie, Y.; Yu, B.; Yan, H. Optical Properties and Polaritons of Low Symmetry 2D Materials. Photon. Insights 2023, 2 (1), R03. (41) Jariwala, D.; Marks, T. J.; Hersam, M. C. Mixed-Dimensional van Der Waals Heterostructures. Nat. Mater. 2017, 16 (2), 170–181. (42) Katzen, J. M.; Tserkezis, C.; Cai, Q.; Li, L. H.; Kim, J. M.; Lee, G.; Yi, G.-R.; Hendren, W. R.; Santos, E. J. G.; Bowman, R. M.; Huang, F. Strong Coupling of Carbon Quantum Dots in Plasmonic Nanocavities. ACS Appl. Mater. Interfaces 2020, 12 (17), 19866–19873. (43) Wang, S.; Yoo, S.; Zhao, S.; Zhao, W.; Kahn, S.; Cui, D.; Wu, F.; Jiang, L.; Utama, M. I. B.; Li, H.; Li, S.; Zibrov, A.; Regan, E.; Wang, D.; Zhang, Z.; Watanabe, K.; Taniguchi, T.; Zhou,  32 C.; Wang, F. Gate-Tunable Plasmons in Mixed-Dimensional van Der Waals Heterostructures. Nat Commun 2021, 12 (1), 5039. (44) Zotev, P. G.; Wang, Y.; Andres‐Penares, D.; Severs‐Millard, T.; Randerson, S.; Hu, X.; Sortino, L.; Louca, C.; Brotons‐Gisbert, M.; Huq, T.; Vezzoli, S.; Sapienza, R.; Krauss, T. F.; Gerardot, B. D.; Tartakovskii, A. I. Van Der Waals Materials for Applications in Nanophotonics. Laser Photonics Rev. 2023, 17 (8), 2200957. (45) Zhang, H.; Abhiraman, B.; Zhang, Q.; Miao, J.; Jo, K.; Roccasecca, S.; Knight, M. W.; Davoyan, A. R.; Jariwala, D. Hybrid Exciton-Plasmon-Polaritons in van Der Waals Semiconductor Gratings. Nat Commun 2020, 11 (1), 3552. (46) Dean, C. R.; Young, A. F.; Meric, I.; Lee, C.; Wang, L.; Sorgenfrei, S.; Watanabe, K.; Taniguchi, T.; Kim, P.; Shepard, K. L.; Hone, J. Boron Nitride Substrates for High-Quality Graphene Electronics. Nat. Nanotechnol. 2010, 5 (10), 722–726. (47) Yu, W.; Li, F.; Huang, T.; Li, W.; Wu, T. Go beyond the Limit: Rationally Designed Mixed-Dimensional Perovskite/Semiconductor Heterostructures and Their Applications. The Innovation 2023, 4 (1), 100363. (48) Lozano, G.; Rodriguez, S. R.; Verschuuren, M. A.; Gómez Rivas, J. Metallic Nanostructures for Efficient LED Lighting. Light Sci Appl 2016, 5 (6), e16080–e16080. (49) Kim, Y.; Kim, J. S.; Lee, T. Strategies to Improve Luminescence Efficiency of Metal‐Halide Perovskites and Light‐Emitting Diodes. Adv. Mater. 2019, 31 (47), 1804595.  33 (50) Gau, D. L.; Ramírez, D.; Riveros, G.; Díaz, P.; Verdugo, J.; Núñez, G.; Lizama, S.; Lazo, P.; Dalchiele, E. A.; Marotti, R. E. Excitonic Origin of the Optical Properties of CsPbBr3. Optical Materials 2024, 157, 116316. (51) Yang, Y.; Yang, M.; Zhu, K.; Johnson, J. C.; Berry, J. J.; Van De Lagemaat, J.; Beard, M. C. Large Polarization-Dependent Exciton Optical Stark Effect in Lead Iodide Perovskites. Nat Commun 2016, 7 (1), 12613. (52) Ruf, F.; Aygüler, M. F.; Giesbrecht, N.; Rendenbach, B.; Magin, A.; Docampo, P.; Kalt, H.; Hetterich, M. Temperature-Dependent Studies of Exciton Binding Energy and Phase-Transition Suppression in (Cs,FA,MA)Pb(I,Br)3 Perovskites. APL Mater. 2019, 7 (3), 031113. (53) Swarnkar, A.; Chulliyil, R.; Ravi, V. K.; Irfanullah, M.; Chowdhury, A.; Nag, A. Colloidal CsPbBr3 Perovskite Nanocrystals: Luminescence beyond Traditional Quantum Dots. Angew. Chem. 2015, 127 (51), 15644–15648. (54) Liu, X.; Lv, J.; Yao, S.; Wang, Y.; Peng, L.; Chen, J.; Liu, X.; Lin, J.; Chen, X. Surface‐Stabilized CsPbI3 Nanocrystals with Tailored Organic Polymer Ligand Binding. Chem. Eur. J. 2023, 29 (26), e202203971. (55) Shen, C.; Xue, Z.; Li, W.; Zeng, W.; Zhu, J.; Dou, Z.-L.; Zhou, L.; Xiao, X.; Gong, J.; Wang, S. Revealing Different Types of Grain Boundaries in Perovskite Films by Intensity-Dependent Fluorescence Lifetime Imaging Microscopy. ACS Photonics 2024, 11 (12), 5439–5445. (56) Peng, B.; Li, Z.; Mutlugun, E.; Hernández Martínez, P. L.; Li, D.; Zhang, Q.; Gao, Y.; Demir, H. V.; Xiong, Q. Quantum Dots on Vertically Aligned Gold Nanorod Monolayer: Plasmon Enhanced Fluorescence. Nanoscale 2014, 6 (11), 5592–5598.  34 (57) Mendelson, N.; Ritika, R.; Kianinia, M.; Scott, J.; Kim, S.; Fröch, J. E.; Gazzana, C.; Westerhausen, M.; Xiao, L.; Mohajerani, S. S.; Strauf, S.; Toth, M.; Aharonovich, I.; Xu, Z. Coupling Spin Defects in a Layered Material to Nanoscale Plasmonic Cavities. Adv. Mater. 2022, 34 (1), 2106046. (58) Li, C.; Wang, Q.; Diao, H.; Hao, Z.; Yu, W.; Liu, K.; Gan, X.; Xiao, F.; Zhao, J. Enhanced Photoluminescence of Monolayer MoSe2 in a Double Resonant Plasmonic Nanocavity with Fano Resonance and Mode Matching. Laser Photonics Rev. 2022, 16 (2), 2100199. (59) Pan, R.; Kang, J.; Li, Y.; Zhang, Z.; Li, R.; Yang, Y. Highly Enhanced Photoluminescence of Monolayer MoS2 in Plasmonic Hybrids with Double-Layer Stacked Ag Nanoparticles. ACS Appl. Mater. Interfaces 2022, 14 (10), 12495–12503. (60) Wen, B.-Y.; Wang, J.-Y.; Shen, T.-L.; Zhu, Z.-W.; Guan, P.-C.; Lin, J.-S.; Peng, W.; Cai, W.-W.; Jin, H.; Xu, Q.-C.; Yang, Z.-L.; Tian, Z.-Q.; Li, J.-F. Manipulating the Light-Matter Interactions in Plasmonic Nanocavities at 1 nm Spatial Resolution. Light Sci Appl 2022, 11 (1), 235.     35 For Table of Contents Use Only Metal-enhanced Photoluminescence in Perovskite Quantum Dots-hBN-Gold Film Mixed-dimensional Van der Waals Heterostructure Kunjie Zhou1§, Jingyi Zhu1§, Ruisi Meng2§, Wei Zeng1, Zhuo Xue1, Chen Shen1, Yueran Zhao3, Yuchen Zhou2, Mengyao Li2, Yanan Wang2, Kenji Watanabe4, Takashi Taniguchi5, Minliang Lai3*, Jia Lin2*, and Sheng Wang1,6* TOC GRAPHICS  Brief synopsis: A pioneering 0D-2D-3D mixed-dimensional van der Waals heterostructure is introduced, composed of 0D semiconducting CsPbBr3 quantum dots, 2D insulating multilayer hexagonal boron nitride (hBN), and 3D conducting gold nanoparticle film. A maximum PL enhancement of 7-fold at an hBN thickness of 26 nm is achieved, and the theoretical simulations further corroborate the experimental observations.     E  g    E  b  f =     I 0  I  I    I 0    f  e x p    f  e x p  𝜂 =  10  − 3 −  10  − 4    f  e x p    f  c a l      f  c a l  e x      f  c a l  e m  | 𝑬 |  | 𝑬 |  𝛥 R / R    f  c a l           𝛾  e x    𝛾  e m      𝛾  e x ′     | 𝑬 | 2    f  e x p   | 𝑬 |  | 𝑬 |  | 𝑬 ′ |  | 𝑬 |      f  c a l  e x =       𝛾  e x ′    𝛾  e x =      |   𝑬 ′ | 2     | 𝑬 | 2  𝛾   𝛾   | i ⟩   | f ⟩    p ^      𝑬 ^  v a c  𝜌 ( 𝜔 )        f  c a l =     f  c a l  e x ∙     f  c a l  e m   S 0   S 1   S 2    𝛾  e x   Γ   QDs     k  nr  QDs      𝛾  e x pl     Γ c  QDs       Γ   pl     k  nr  pl    𝜂 0    𝜏 0       𝜂 0  =    Γ   QDs   𝜏 0 #  ( 2 )       𝜏  0   =   1   Γ   QDs +    k  nr  QDs #  ( 3 )       𝜏  0   =   1   Γ   QDs +    k  nr  QDs #  ( 3 )  𝜂  𝜏     𝜂   =   (  Γ   QDs +  Γ   pl ) 𝜏 #  ( 4 )     𝜏 =  1   Γ   QDs +        𝜏 =  1   Γ   QDs +      Γ   QDs +  Γ   pl     k  nr  QDs +    k q  QDs +    k  nr  pl   S 1   S 0    𝛾  e x      k nr QDs    𝛤 QDs      𝛾  e x pl      k q QDs      𝛤 c QDs    𝛤 pl :     k  nr  pl  𝜏    𝜏 0  I  ( t ) =   A 1  exp ⁡   ( −   t    𝜏 1 ) +   A 2  exp ⁡   ( −   t    𝜏 2 )    𝜏 -    𝜏 - =   (   A 1     𝜏 1 2 +   A 2     𝜏 2 2 )  (   A 1   𝜏 1 +   A 2   𝜏 2 )      𝜏 - 0 =    𝜏 1    𝜏 2    A 1    A 2    𝜏 -   Γ   pl     k q  QDs +    k  nr  pl   Γ   pl     k q  QDs +    k  nr  pl    𝜏 -  𝛥 R / R  𝛥 R / R    I  s a m p l e    I  s u b s t r a t e  𝛥 R / R =   (   I  s a m p l e −   I  s u b s t r a t e )    I  s u b s t r a t e