Plasmon-induced Hot Electron Transfer Research Articles

(Invited) Plasmon Induced Hot Electron Transfer from Doped Semiconductor Nanocrystals

In recent years, a new class of plasmonic materials based on doped semiconductor NCs has been developed. Similar to noble metals, localized surface plasmon resonances in doped semiconductor NCs arises from the coherent collective oscillation of free carriers within the NCs. The wide tunability of free carrier concentration results in tunable plasmon bands spanning from the visible to mid-infrared regime and these plasmonic semiconductor NCs have been reported to drive plasmonic hot carrier photocatalysis under near IR light illumination. These reports suggest that plasmonic semiconductors is an interesting material platform for efficient near IR driven hot carrier photocatalysis. So far the reported efficiencies are low and the mechanisms of hot carrier generation, transfer and recombination are unclear. There are interesting similarities and differences between metal and semiconductor plasmonics. First, plasmons in semiconductors can decay by inter- (band gap) and intra- band plasmon decay. Furthermore, charge transfer transition in semiconductor heterostructures have been extensively reported; can plasmon decay in plasmonic-semiconductor/semiconductor junctions proceed by exciting interfacial ET across the junction, similar to the PICTT pathway reported for metal/semiconductor junctions? Second, in plasmonic semiconductor materials, where there is a lack of states within the p-semiconductor bandgap, the transferred electrons in the accepting semiconductor CB can recombine only with the VB holes in the plasmonic semiconductor. This process requires dissipation of ~ >1 eV energy, which may slow down the recombination rate. In this talk, I will discuss our recent progresses in studying plasmon induced hot electron transfer and recombination in plasmonic semiconductor/semiconductor interfaces.

SERS Detection of Trace Carcinogenic Aromatic Amines Based on Amorphous MoO3 Monolayers.

Aromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a-MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot-electron fast decay component of a-MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon-induced hot-electron transfer (PIHET) process from a-MoO3 to MO. Therefore, a-MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM-PIHET synergistic mechanism in a-MoO3. In addition, a-MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c-MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o-aminoazotoluene (o-AAT) is 10-9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a-MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates.

SERS Detection of Trace Carcinogenic Aromatic Amines Based on Amorphous MoO3 Monolayers

AbstractAromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a‐MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot‐electron fast decay component of a‐MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon‐induced hot‐electron transfer (PIHET) process from a‐MoO3 to MO. Therefore, a‐MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM‐PIHET synergistic mechanism in a‐MoO3. In addition, a‐MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c‐MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o‐aminoazotoluene (o‐AAT) is 10−9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a‐MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates.

Elucidating Facet-Dependent Photocatalytic Activities of Metastable CdS and Au@CdS Core-Shell Nanocrystals.

Controlling the crystal facets of semiconductor nanocrystals (NCs) has been proven as an effective approach to tune their physicochemical properties. However, the study on facet-engineering of metastable zinc blende CdS (zb-CdS) and its heterostructures is still not fully explored. In this study, the zb-CdS and Au@zb-CdS core-shell NCs with tunable terminating facets are controllably synthesized, and their photocatalytic performance for water splitting are evaluated. It is found that the {111} facets of the zb-CdS NCs display higher intrinsic activity than the {100} counterparts, which originates from these surfaces being much more efficient, facilitating electron transition to enhance the adsorption ability and the dissociation of the adsorbed water, as revealed by theoretical calculations. Moreover, the Au@zb-CdS core-shell NCs exhibit better photocatalytic performance than the zb-CdS NCs terminated with the same facets under visible light irradiation (≥400 nm), which is mainly ascribed to the accelerated electron separation at the interface, as demonstrated by femtosecond transient absorption (fs-TA) spectroscopy. Importantly, the quantum yield of plasmon-induced hot electron transfer quantified by fs-TA in the Au@zb-CdS core-shell octahedrons can be reached as high as 1.2% under 615 nm excitation, which is higher than that of the Au@zb-CdS core-shell cubes. This work unravels the face-dependent photocatalytic performance of the metastable semiconductor NCs via a combination of experiments and theoretical calculations, providing the understanding of the underlying mechanism of these photocatalysts.

Perovskite quantum laser with enhanced population inversion driven by plasmon-induced hot electron transfer under potential shift polarization conditions

The hot electron transfer resulting in fluorescence enhancement is significantly meaningful for theory and experiment of the study on photoelectric devices. However, the laser emission based on direct hot electron transfer is difficult to realize because of the low transfer efficiency. To achieve a laser with a new-generation mechanism based on hot electron transfer, the photoelectric co-excitation is proposed for improving the efficiency of hot electron transfer. The lasing behavior at 532 nm is realized with a threshold of 5 kw cm−2 and 1 μA, which can be considered as the hot electron transfer resulting in population inversion enhancement. Meanwhile, the lasing output power is 0.3 mW. The hot electrons transfer process was described via the transient absorption spectrum according to the improved ground-state bleaching and excited-state absorption signal in device ON. Through comparison with the optical pump only, the quantum efficiencies of hot electron generation (HEG) and hot electron transfer (HET) were increased ∼31% and 31%, respectively. Most importantly, a triple gain mode coupling device including local surface plasmon, hot electron transfer, and array oscillation was presented. Two modes of population inversion enhancement are proposed. This study can provide theoretical and experimental reference for the research of hot electron lasers and devices.

Direct Hot-Electron Transfer at the Au Nanoparticle/Monolayer Transition-Metal Dichalcogenide Interface Observed with Ultrahigh Spatiotemporal Resolution.

Plasmon-induced hot-electron transfer at the metallic nanoparticle/semiconductor interface is the basis of plasmon-enhanced photocatalysis and energy harvesting. However, limited by the nanoscale size of hot spots and femtosecond time scale of hot-electron transfer, direct observation is still challenging. Herein, by using spatiotemporal-resolved photoemission electron microscopy with a two-color pump-probe beamline, we directly observed such a process with a concise system, the Au nanoparticle/monolayer transition-metal dichalcogenide (TMD) interface. The ultrafast hot-electron transfer from Au nanoparticles to monolayer TMDs and the plasmon-enhanced transfer process were directly measured and verified through an in situ comparison with the Au film/TMD interface and free TMDs. The lifetime at the Au nanoparticle/MoSe2 interface decreased from 410 to 42 fs, while the photoemission intensities exhibited a 27-fold increase compared to free MoSe2. We also measured the evolution of hot electrons in the energy distributions, indicating the hot-electron injection and decay happened in an ultrafast time scale of ∼50 fs without observable electron cooling.

Methanol steam reforming for hydrogen production driven by an atomically precise Cu catalyst

Plasmon-induced hot-electron transfer from metal nanostructures is being intensely pursed in current photocatalytic research, however it remains elusive whether molecular-like metal clusters with excitonic behavior can be used as light-harvesting materials in solar energy utilization such as photocatalytic methanol steam reforming. In this work, we report an atomically precise Cu13 cluster protected by dual ligands of thiolate and phosphine that can be viewed as the assembly of one top Cu atom and three Cu4 tetrahedra. The Cu13H10(SR)3(PR’3)7 (SR = 2,4-dichlorobenzenethiol, PR’3 = P(4-FC6H4)3) cluster can give rise to highly efficient light-driven activity for methanol steam reforming toward H2 production.

Plasmon-Induced Charge Transfer-Enhanced Raman Scattering on a Semiconductor: Toward Amplification-Free Quantification of SARS-CoV-2.

Semiconductors demonstrate great potentials as chemical mechanism-based surfaceenhanced Raman scattering (SERS) substrates in determination of biological species in complex living systems with high selectivity. However, low sensitivity is the bottleneck for their practical applications, compared with that of noble metal-based Raman enhancement ascribed to electro-magnetic mechanism. Herein, a novel Cu2O nanoarray with free carrier density of 1.78*1021 cm-3 comparable to that of noble metals was self-assembled, creating a record in enhancement factor (EF) of 3.19×1010 among semiconductor substrates. The significant EF was mainly attributed to plasmon-induced hot electron transfer (PIHET) in semiconductor which was neverreported before. This Cu2O nanoarray was subsequently developed as a highly sensitive and selective SERS chip for non-enzyme and amplification-free SARS-CoV-2 RNA quantification with a detection limit down to 60 copies/mL within 5 min. This unique Cu2O nanoarray demonstrated the significant Raman enhancement through PIHET process, enabling rapid and sensitive point-of-care testing of emerging virus variants.

Plasmon‐Induced Charge Transfer‐Enhanced Raman Scattering on a Semiconductor: Toward Amplification‐Free Quantification of SARS‐CoV‐2

AbstractSemiconductors demonstrate great potentials as chemical mechanism‐based surface‐enhanced Raman scattering (SERS) substrates in determination of biological species in complex living systems with high selectivity. However, low sensitivity is the bottleneck for their practical applications, compared with that of noble metal‐based Raman enhancement ascribed to electromagnetic mechanism. Herein, a novel Cu2O nanoarray with free carrier density of 1.78×1021 cm−3 comparable to that of noble metals was self‐assembled, creating a record in enhancement factor (EF) of 3.19×1010 among semiconductor substrates. The significant EF was mainly attributed to plasmon‐induced hot electron transfer (PIHET) in semiconductor which was never reported before. This Cu2O nanoarray was subsequently developed as a highly sensitive and selective SERS chip for non‐enzyme and amplification‐free SARS‐CoV‐2 RNA quantification with a detection limit down to 60 copies/mL within 5 min. This unique Cu2O nanoarray demonstrated the significant Raman enhancement through PIHET process, enabling rapid and sensitive point‐of‐care testing of emerging virus variants.

Epitaxial growth of highly symmetrical branched noble metal-semiconductor heterostructures with efficient plasmon-induced hot-electron transfer

Epitaxial growth is one of the most commonly used strategies to precisely tailor heterostructures with well-defined compositions, morphologies, crystal phases, and interfaces for various applications. However, as epitaxial growth requires a small interfacial lattice mismatch between the components, it remains a challenge for the epitaxial synthesis of heterostructures constructed by materials with large lattice mismatch and/or different chemical bonding, especially the noble metal-semiconductor heterostructures. Here, we develop a noble metal-seeded epitaxial growth strategy to prepare highly symmetrical noble metal-semiconductor branched heterostructures with desired spatial configurations, i.e., twenty CdS (or CdSe) nanorods epitaxially grown on twenty exposed (111) facets of Ag icosahedral nanocrystal, albeit a large lattice mismatch (more than 40%). Importantly, a high quantum yield (QY) of plasmon-induced hot-electron transferred from Ag to CdS was observed in epitaxial Ag-CdS icosapods (18.1%). This work demonstrates that epitaxial growth can be achieved in heterostructures composed of materials with large lattice mismatches. The constructed epitaxial noble metal-semiconductor interfaces could be an ideal platform for investigating the role of interfaces in various physicochemical processes.

Active Manipulation of Luminescent Dynamics via Au NPs‐CsPbBr3 Interfacial Engineering

AbstractManipulating photocarrier dynamics for luminescent materials is fundamentally important for steering luminescent properties of optoelectronic devices. Here, interfacial engineering is realized by constructing Au NPs‐CsPbBr3 interfaces toward resonant coupling between localized surface plasmon and exciton. Through ultrafast laser spectroscopic measurements, it is demonstrated that photoluminance originating from CsPbBr3 excitonic recombination is significantly enhanced at the interface with prolonged lifetimes. Interfacial photocarrier dynamics are mediated by plasmon‐induced hot electron transfer (PHET) and plasmon‐induced resonant energy transfer (PIRET) processes. By simply varying excitation laser wavelengths, PHET path of photocarriers is actively switched on and off. The results are of great significance for actively manipulating photocarrier dynamics of perovskite luminescent devices.

Optoelectronics of Atomic Metal-Semiconductor Interfaces in Tin-Intercalated MoS2.

Metal-semiconductor interfaces are ubiquitous in modern electronics. These quantum-confined interfaces allow for the formation of atomically thin polarizable metals and feature rich optical and optoelectronic phenomena, including plasmon-induced hot-electron transfer from metal to semiconductors. Here, we report on the metal-semiconductor interface formed during the intercalation of zero-valent atomic layers of tin (Sn) between layers of MoS2, a van der Waals layered material. We demonstrate that Sn interaction leads to the emergence of gap states within the MoS2 band gap and to corresponding plasmonic features between 1 and 2 eV (0.6-1.2 μm). The observed stimulation of the photoconductivity, as well as the extension of the spectral response from the visible regime toward the mid-infrared suggests that hot-carrier generation and internal photoemission take place.

(Invited) Enhanced Water Splitting at Visible Wavelength Region Using Modal Strong Coupled Photoanode and Photocathode

Plasmon-induced hot electron transfer at the metal/semiconductor interface has attracted considerable attention as a novel mechanism to promote artificial photosynthesis under visible and near-infrared irradiation.[1-4] However, a single layer of gold nanoparticles (Au-NPs) cannot efficiently harvest light.Recently, we reported that the modal strong coupling between a Fabry–Pérot (F-P) nanocavity mode and a localized surface plasmon resonance (LSPR) facilitates water splitting reactions.[5] We used a Au-NPs/TiO2/Au-film (ATA) structure as a photoanode. The TiO2/Au-film component of this photoanode acts as F-P nanocavity. The light absorption of the ATA was promoted by the optical hybrid modes based on the strong coupling formation across a broad range of wavelengths, followed by a hot electron transfer to TiO2. We observed an 11-fold increase in the incident photon-to-current conversion efficiency (IPCE) with respect to a photoanode structure without Au-film. Importantly, the internal quantum efficiency (IQE) was enhanced 1.5 times under a strong coupling over that under uncoupled conditions.We speculated that the coupling strength of the modal strong coupling affects the hot electron transfer efficiency. To increase the coupling strength, we developed a photoanode consisting of Au-Ag alloy nanoparticles /TiO2/Au-film (AATA).[6] It was expected that the splitting energy of the modal strong coupling system increase with increasing LSPR oscillator strength by mixing Ag in the nanoparticle. The AATA structure formed under modal strong coupling with a large splitting energy of 520 meV, which can be categorized into the ultrastrong coupling regime. The AATA photoanode showed a 4.0% maximum IPCE obtained at 580 nm, and the IQE was 4.1%. Additionally, the highly efficient hot-electron injection on AATA was directly observed by transient absorption measurements. Furthermore, hybrid mode-induced water oxidation using AATA structures was performed with a Faraday efficiency of more than 70% for O2 evolution.We have applied the concept of photoanodes with modal strong coupling to photocathodes as well. As a semiconductor for constructing F-P nanocavity, we employed p-type nickel oxide (NiO) which is capable of transferring holes generated in Au-NPs and fabricated a photocathode consisting of Au-NP/NiO/Pt-film (ANP).[7] The ANP structure can absorb visible light over a wide wavelength range from 500 nm to 850 nm due to a hybrid mode based on the modal strong coupling. The IPCE based on H2evolution through water/proton reduction by hot electrons reached 0.2% at 650 nm and 0.04% at 800 nm, which was significantly larger than that of Au-NPs on NiO without Pt-film. Y. Nishijima, K. Ueno, Y. Kotake, K. Murakoshi, H. Inoue, H. Misawa, J. Phys. Chem. Lett. 2012, 3, 1248-1252. Y. Zhong, K. Ueno, Y. Mori, X. Shi, T. Oshikiri, K. Murakoshi, H. Inoue, H. Misawa, Angew. Chem. Int. Ed. 2014, 53, 10350-10354. T. Oshikiri, K. Ueno, H. Misawa, Angew. Chem. Int. Ed. 2016, 55, 3942-3946. M. Okazaki, Y. Suganami, N. Hirayama, H. Nakata, T. Oshikiri, T. Yokoi, H. Misawa, K. Maeda, ACS Appl. Energy Mater. 2020, 3, 5142–5146. X. Shi, K. Ueno, T. Oshikiri, Q. Sun, K. Sasaki, H. Misawa, Nat. Nanotechnol. 2018, 13, 953-958. Y. Suganami, T. Oshikiri, X. Shi, H. Misawa, Angew. Chem. Int. Ed. 2021, 60, 18438-18442. T. Oshikiri, H. Jo, X. Shi, and H. Misawa, Chem. Eur. J. 2022, published online, DOI: 10.1002/chem.202200288

Enhanced transfer efficiency of plasmonic hot-electron across Au/GaN interface by the piezo-phototronic effect

Performances of plasmon-mediated optoelectronic devices are mainly limited by the transfer efficiency of the energetic hot electrons (QEHET) from metallic nanostructures into the semiconductor active region. Here, we report a novel strategy to enhance the efficiency of plasmon-induced hot-electron transfer (PHET) across Au nanoparticles (NPs)/GaN film via the external-strain-induced piezo-phototronic effect. By performing transient absorption (TA) spectrum measurement of the Au NPs/GaN freestanding membrane under different strain conditions, the enhancement of effective QEHET is estimated to be nearly 120% under 3.57% compressive straining. This enhancement is comparable or better than previously reported achievement using other methods such as controlling the material’s morphology or optimizing charge-transfer transition pathway. The mechanisms of the piezo-phototronic enhanced PHET rely on the modulated barrier height between Au NPs/GaN heterojunction. This was further confirmed by performing the photoresponse ability measurements in Au NPs/GaN film under external straining. Photoresponsivity of the plasmonic heterojunction is obviously increased/decreased when the hybrid membrane undergoes compressive/tensile strain. These results advance our understanding of the piezo-phototronic effect on QEHET in plasmonic heterostructures, and offer effective strategies to manipulate hot carrier dynamics for high-performance plasmonic devices and photoelectrochemical systems.

Bright CdSe/CdS Quantum Dot Light-Emitting Diodes with Modulated Carrier Dynamics via the Local Kirchhoff Law.

Addressing the interactions between optical antennas and ensembles of emitters is particularly challenging. Charge transfer and Coulomb interactions complicate the understanding of the carrier dynamics coupled by antennas. Here, we show how Au antennas enhance the luminescence of CdSe/CdS quantum dot assemblies through carrier dynamics control within the framework of the local Kirchhoff law. The Au antennas inject hot electrons into quantum dot assemblies via plasmon-induced hot electron transfer that increases the carrier concentration. Also, the localized surface plasmon resonances of Au antennas favorably tilt the balance between nonradiative Auger processes and radiative recombination in the CdSe core. Eventually, a high bright (125,091.6 cd/m2) deep-red quantum dot light-emitting diode is obtained by combining with Au antennas. Our findings suggest a new understanding of light emission of assembled emitters coupled by antennas, which is of essential interest for the description of light-matter interaction in advanced optoelectronics.

Tuning the Optical Band Gap of Two-Dimensional WS2 Integrated with Gold Nanocubes by Introducing Palladium Nanostructures

The two characteristic absorption peaks of semiconducting two-dimensional tungsten disulfide (WS2) are red-shifted after integrating with gold nanocube (AuNC) arrays. The amount of the red shift is reduced when the AuNCs are coated with a high concentration of Pd. A negligible shift was observed in the absorption peaks of WS2 when smaller amounts of Pd are introduced to the surface of AuNCs. Conversely, the photoluminescence (PL) of WS2 is blue-shifted when measured on top of AuNCs and AuNCs coated with different amounts of Pd. AuNC-Pd Janus nanoparticles are prepared by depositing Pd atoms asymmetrically on AuNCs assembled into 2-D arrays on the surface of a glass substrate by the chemical reduction of Pd ions. Due to the large AuNC or AuNC-Pd/WS2 Schottky barrier, the plasmon-induced hot electron transfer (PHET) from AuNCs and AuNCs coated with a high concentration of Pd is responsible for the red shift of the absorption spectrum of WS2. Introducing a lower concentration of Pd to AuNCs increases the Schottky barrier further due to the formation of the Au-Pd equilibrium Fermi level of lower energy, reducing the efficiency of PHET. The effect of Pd on the Fermi level of AuNCs vanishes at high Pd deposition. Pauli blocking and phase-space filling are responsible for the blue shift of PL of WS2 on top of AuNCs and AuNCs coated with Pd. The Pauli blocking effect is directly proportional to the PHET efficiency. This explains the significant blue shift of PL of WS2 after integrating with AuNCs and AuNCs coated with a high concentration of Pd. Additionally, depositing Pd onto AuNCs elongates the lifetime of the hot electrons and enhances the PHET efficiency.

Self-powered flexible photodetectors based on Ag nanoparticle-loaded g-C3N4 nanosheets and PVDF hybrids: role of plasmonic and piezoelectric effects

Here we demonstrate novel self-powered photodetection using silver (Ag) nanoparticle-loaded two-dimensional graphitic carbon nitride (g-C3N4) nanosheets triggered by poly-vinylidene fluoride (PVDF)-based flexible piezoelectric nanogenerators. A self-poled PVDF-based nanogenerator has been obtained upon exploiting pristine g-C3N4 nanosheets as a filler material within the PVDF matrix. The fabricated nanogenerator devices are found to be highly efficient in generating the maximum voltage of ∼2.3 V and maximum power ∼110 μWatt/cm2, upon finger tapping. Further, the integration of an additional layer of plasmonic Ag nanoparticle-loaded g-C3N4 nanosheets, has led to a significant enhancement of photoresponse. The hybrid plasmonic nanogenerator (with a strain of ∼0.021%) has resulted in self-powered photodetection with a photo-to-dark current ratio of ∼60, as compared to the unstrained device (∼2.0). In contrast to the usual behaviour (positive photoresponse), the exposure of an ultraviolet light lowers the output current indicating a negative photoresponse reported for the first time in such a system. The origin of such negative photoresponse has been attributed to the screening of piezopotential of PVDF by photogenerated carriers of g-C3N4 nanosheets. On the other hand, visible light-induced positive photoresponse has originated from the increment in the current, indicating the useful role of Ag nanoparticles in plasmon-induced hot electron transfer process.

Efficient Hot Electron Transfer from Small Au Nanoparticles.

Many important chemical transformations enabled by plasmonic hot carrier photocatalysis have been reported, although their efficiencies are often too low for practical applications. We examine how the efficiency of plasmon-induced hot electron transfer depends on the Au particle size in Au-tipped CdS nanorods. We show that with decreasing Au size, the plasmon width increases due to enhanced surface damping contributions. The excitation of Au nanoparticles leads to an instrument response time-limited ultrafast hot electron transfer process to CdS (≪140 fs). The quantum efficiency of this process increases from ∼1% to ∼18% as the particle size decreases from 5.5 ± 1.1 to 1.6 ± 0.5 nm due to both enhanced hot electron generation and transfer efficiencies in small Au particles. Our finding suggests that decreasing plasmonic particle size is an effective approach for improving plasmon-induced hot carrier transfer efficiency and provides important insight for the rational improvement of plasmonic hot carrier-based devices.

Plasmon-Induced Interfacial Hot-Electron Transfer Directly Probed by Raman Spectroscopy

Summary Plasmon-mediated photocatalysis via hot-electron transfer attracts increasing interest due to its capability to improve energy utilization efficiency. However, more insightful information is still needed to reveal the mechanism of interfacial hot-electron transfer. Herein, the plasmon-induced hot-electron transfer at different plasmonic interfaces, including Au-insulator (SiO2), Au-semiconductor (TiO2 and Cu2O), and Au-metal (Pd and Pt), is directly investigated using surface-enhanced Raman spectroscopy (SERS) and density functional theory calculation with a (sub)nanometer spatial resolution, through the fabrication of well-defined plasmonic nanostructures. (Sub)nanometer-distance dependence of interfacial hot-electron transfer has been identified for the first time. Hot electrons can migrate across the Au-semiconductor or Au-metal interfaces and transfer more than 10 nm in semiconductors but decay to thermally equilibrated states rapidly in metals in less than 1 nm. Such a transfer process is blocked at the Au-insulator interface. This work promotes the fundamental understanding of plasmon-induced hot-electron transmission and photocatalysis at plasmonic interfaces.

Hot electron injection induced electron–hole plasma lasing in a single microwire covered by large size Ag nanoparticles

In addition to the plasmon-mediated resonant coupling mechanism, plasmon-induced hot electron transfer can provide an alternative approach to construct high-performance optoelectronic devices for various applications.