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Fast Photoelectric Conversion in the Near‐Infrared Enabled by Plasmon‐Induced Hot‐Electron Transfer
摘要： Interfacial charge transfer is a fundamental and crucial process in photoelectric conversion. If charge transfer is not fast enough, carrier harvesting can compromise with competitive relaxation pathways, e.g., cooling, trapping, and recombination. Some of these processes can strongly affect the speed and efficiency of photoelectric conversion. In this work, it is elaborated that plasmon-induced hot-electron transfer (HET) from tungsten suboxide to graphene is a sufficiently fast process to prevent carrier cooling and trapping processes. A fast near-infrared detector empowered by HET is demonstrated, and the response time is three orders of magnitude faster than that based on common band-edge electron transfer. Moreover, HET can overcome the spectral limit of the bandgap of tungsten suboxide (≈2.8 eV) to extent the photo-response to the communication band of 1550 nm (≈0.8 eV). These results indicate that plasmon-induced HET is a new strategy for implementation of efficient and high-speed photoelectric devices.
关键词： localized surface plasmon resonance,infrared photodetection,photoelectric conversion,hot-electron transfer,graphene
更新于2025-09-11 14:15:04
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Overall water splitting and hydrogen peroxide synthesis by gold nanoparticle-based plasmonic photocatalysts
摘要： Gold nanoparticle-based plasmonic photocatalysts can be driven by excitation of the localized surface plasmon resonance. Among them, hot-electron transfer-type photocatalysts have recently attracted interest as promising solar-to-chemical converters owing to the wide spectral response from visible-to-infrared light. This Minireview highlights recent studies on two kinds of artificial photosynthesis - water splitting and H2O2 synthesis from water and oxygen - using hot-electron transfer-type plasmonic photocatalysts with particular emphasis placed on the electrocatalysis of Au nanoparticles.
关键词： water splitting,gold nanoparticle,hot-electron transfer,hydrogen peroxide synthesis,plasmonic photocatalysts
更新于2025-09-11 14:15:04
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Effect of Hot-Electron Injection on the Excited-State Dynamics of a Hybrid Plasmonic System Containing Poly(3-hexylthiophene)-Coated Gold Nanoparticles
摘要： We investigated the photophysical interaction between a conjugated polymer (CP) and a plasmonic gold nanoparticle (Au NP) using transient absorption spectroscopy. We prepared a hybrid system containing CP-stabilized Au NPs by reducing a Au precursor directly with a thiol-terminated poly(3-hexylthiophene) surfactant (P3HT-SH), with the unreacted P3HT-SH chains used as an organic matrix. The P3HT attached to the Au NPs plays two critical roles in our hybrid system: it suppresses exciton quenching from the P3HT matrix to Au NPs (the spacer role) and relays hot electrons induced by surface plasmon resonance of Au NPs to P3HT (the bridge role). Thus, singlet excitons are more slowly relaxed in our hybrid system than those in a neat P3HT film. Our findings may provide important information for development of the high-efficiency hybrid optoelectronic devices.
关键词： surface plasmon resonance,transient absorption spectroscopy,conjugated polymer,photophysical interaction,plasmonic gold nanoparticle,optoelectronic devices,hot-electron injection
更新于2025-09-11 14:15:04
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Hot-electron photodetector with wavelength selectivity in near-infrared via Tamm plasmon
摘要： Tamm plasmonic (TP) structures, consisting of a metallic film and a distributed Bragg reflector (DBR), can exhibit pronounced light confinement allowing for enhanced absorption in the metallic film at the wavelength of the TP resonance. This wavelength dependent absorption can be converted into an electrical signal through the internal photoemission of energetic hot-electrons from the metallic film. Here, by replacing the metallic film at the top of a TP structure with a hot-electron device in a metal-semiconductor-ITO (M-S-ITO) configuration, for the first time, we experimentally demonstrate a wavelength-selective photoresponse around the telecommunication wavelength of 1550 nm. The M-S-ITO junction is deliberately designed to have a low energy barrier and an asymmetrical hot-electron generation, in order to guarantee a measurable net photocurrent even for sub-bandgap incident light with a photon energy of 0.8 eV (1550 nm). Due to the excitation of TPs between the metallic film in the M-S-ITO structure and the underlying DBR, the fabricated TP coupled hot-electron photodetector exhibits a sharp reflectance dip with a bandwidth of 43 nm at a wavelength of 1581 nm. The photoresponse matches the absorptance spectrum, with a maximum value of 8.26 nA/mW at the absorptance peak wavelength that decreases by more than 80% when the illumination wavelength is varied by only 52 nm (from 1581 to 1529 nm), thus realizing a high modulation wavelength-selective photodetector. This study demonstrates a high-performance, lithography-free, and wavelength-selective hot-electron near-infrared photodetector structure.
关键词： hot-electron photodetector,near-infrared,wavelength-selective photodetection,Tamm plasmonic structures,telecommunication wavelength
更新于2025-09-11 14:15:04
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The chemical potential of plasmonic excitations
摘要： By the photoexcitation of localized surface plasmon resonances of metal nanoparticles, one can generate reaction equivalents for driving redox reactions. We show that, in such cases, there is a chemical potential contributed by the plasmonic excitation. This chemical potential is a function of the concentration of light, as we determine from the light intensity-dependent activity in plasmon-excitation-driven CO2 reduction on Au nanoparticles. Our finding allows the treatment of plasmonic excitation as a reagent in chemical reactions; the chemical potential of this reagent is tunable by the light intensity.
关键词： hot electron,catalysis,CO2 reduction,photocatalysis,LSPR
更新于2025-09-11 14:15:04
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Enhancing Photothermal Effect and Stability of Plasmonic Pd/Ag‐Nanosheet by Nanoassembly for Efficient Light‐Driven Catalytic Organic Hydrogenation
摘要： Due to the ability to harness surface plasmons to promote solar-to-chemical energy conversion, plasmonic nanoparticles with finely-controlled structure and optical properties hold great promise for light-activated catalysis. Herein, we prepared a strong plasmonic nanostructure, by assembling Pd/Ag nanosheets (NSs) with varied Pd/Ag ratio onto the surface of polystyrene (PS) microsphere to form a spherical nanoassembly (NAs). The as-prepared Pd/Ag-PS NAs showed better photothermal performance than the precursor Pd/Ag NSs of the same concentration. More importantly, the as-prepared Pd/Ag-PS NAs can be used to boost light-driven organic hydrogenation reactions, in which Pd nanocomponent acts as hydrogenation reaction active sites and Pd/Ag-NSs can convert light efficiently into heat. Under room temperature conditions, the light-driven catalytic hydrogenation efficiency under 50 mW/cm2 full-spectrum irradiation proved to be comparable to that of thermally (70 °C) driven reactions. Moreover, the as-prepared Pd/Ag-PS NAs has better photostability than Pd/Ag NSs. The results proved that the photothermal effect rather than the transfer of hot electrons is responsible for enhanced photocatalytic hydrogenation performance. The strong plasmon coupling between closely-packed Pd/Ag NSs enhances the electromagnetic field intensity and scattering intensity and increase Vis-NIR light trapping and high density hot spots generation, which lead to an overall better photocatalytic efficiency.
关键词： photocatalytic hydrogenation,photothermal effect,hot-electron,surface plasmon resonant coupling,Pd/Ag-nanosheet nanoassembly
更新于2025-09-11 14:15:04
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Miniaturized Optoelectronic SPR Sensor Based on Integrated Planar Waveguide and MIM Hot-Electron Photodetector
摘要： There is an increasing interest in miniaturized surface plasmon resonance (SPR) sensors for portable biosensing. Toward this goal, removing the use of an external spectrometer is a fundamental step to miniaturize the Kretschmann SPR sensors. In this article, we have proposed a new architecture of the SPR sensor with an electrical response in which the integrated hot-electron photodetector replaces the traditional spectrometer. In this device, the metal–insulator–metal (MIM) junction and planar waveguide (PWG) are integrated together as a multilayer. The structure is excited by a broad-spectrum light-emitting diode (LED) in the near-IR region. The coupling between the surface plasmon polariton (SPP) mode of the MIM junction and the PWG mode leads to predominated photoabsorption in the top layer of the MIM junction within a selective narrowband of excitation bandwidth. The center wavelength of the absorption band is determined by the refractive index of the analyte. We demonstrate that based on the hot-electron injection in the MIM junction, the open-circuit voltage of the MIM junction in the proposed architecture is proportional to the refractive index of the analyte and this feature can replace the wavelength interrogation of the SPR sensors. We show that electrical sensitivity can be improved by introducing an indium tin oxide (ITO) layer as a hot-electron blocker above the bottom electrode of the MIM junction. The response of the proposed sensor is calculated in detail, and its optical sensitivity is estimated to be ～8000 nm/refractive index unit (RIU), which turns to an electrical sensitivity of 12.5 V/RIU in our device.
关键词： refractive index sensor,metal–insulator–metal (MIM) junction,surface plasmon resonance (SPR),Hot-electron
更新于2025-09-11 14:15:04
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Broadening the IF band of a THz hot electron bolometer mixer by using a magnetic thin film
摘要： To expand the intermediate frequency (IF) band and improve the sensitivity of a hot electron bolometer mixer (HEBM), we proposed and examined a new HEBM structure using a magnetic thin film. We found that it was possible to suppress the superconductivity of the 5-nm thick niobium nitride (NbN) thin film by the addition of a 1.8-nm thick nickel (Ni) thin film. It was also confirmed that the superconductivity disappeared in the Au (70 nm)/Ni (1.8 nm)/NbN (5 nm) tri-layer for forming the electrodes of the HEBM. By using the magnetic thin film for the electrodes, we suggested that the superconductivity of the HEBM strip would be affected and that hot spots would form near the electrodes. This approach is effective for shortening the hot electron drift length and will lead to the expansion of the IF bandwidth. We think that the new structure lowers the required local oscillator (LO) power and improves the HEBM sensitivity by suppressing the proximity effect under the electrode. The IF bandwidth of the fabricated Ni-HEBMs was evaluated at 1.9 THz. We confirmed that the IF bandwidth expands, and the evaluated bandwidths were in the range of 5.1–5.7 GHz at 4 K. Ni-HEBMs with 0.1 μm strip length were also fabricated and evaluated. The IF bandwidth was about 6.9 GHz at 4 K.
关键词： hot electron bolometer mixer,THz,magnetic thin film,superconductivity,intermediate frequency band
更新于2025-09-11 14:15:04
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Hot-Electron Trapping and Hole-Induced Detrapping in GaN-Based GITs and HD-GITs
摘要： This paper investigates the trapping mechanisms in gate-injection transistors (GITs) without and with a pdrain electrode, referred to as GITs and Hybrid-Drain-embedded GITs (HD-GITs), respectively, used to inject holes and reduce charge trapping effects. We compare the two sets of devices under both the OFF-state and semi-ON state, to investigate the role of hot electrons in favoring the charge trapping. The analysis is based on combined pulsed characterization, transient measurements, and electroluminescence (EL) characterization. We demonstrate the following relevant results: 1) GITs and HD-GITs have comparable and negligible dynamic RON when trapping is induced in the OFF-state; under semi-ON state conditions, GITs suffer from significant dynamic RON, while HD-GITs show no additional trapping with respect to OFF-state; 2) EL characterization carried out until VDS = 500 V in semi-ON conditions shows comparable features, suggesting that the electric field and hot-carrier density are similar in GITs and HD-GITs. This result indicates that the hot-electron trapping rate is identical for the two sets of samples, so the difference observed in dynamic RON must be ascribed to a different detrapping rate; 3) transient RON measurements indicate that the traps filled in the OFF-state conditions are the same as those filled by hot electrons in semi-ON, with Ea = 0.8 eV (possibly CN); and 4) EL analysis under constant bias indicates that in GITs there is a time-dependent increase in the luminescence signal at the drain terminal, when the devices are biased with VDS = 300 V. Such effect, indicative of hot-electron trapping, is not observed in HD-GITs. Based on the experimental evidence collected within this paper, we conclude that—in the semi-ON state—the main difference between GITs and HD-GITs consists in a faster detrapping rate of hot electrons, achieved through hole injection from the pdrain terminal.
关键词： gate-injection transistors (GITs),Electroluminescence (EL),gallium nitride (GaN) HEMT,trapping,hot electron
更新于2025-09-10 09:29:36
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Disentangling the Electron and Hole Dynamics in Janus CdSe/PbSe Nanocrystals through Variable Pump Transient Absorption Spectroscopy
摘要： CdSe/PbSe Janus hetero-nanocrystals (HNCs) represent an interesting system where structurally immiscible CdSe and PbSe co-exist in a single structure with intermixed electronic states. Here, we have investigated the carrier dynamics in Janus CdSe/PbSe HNCs through ultrafast transient absorption spectroscopy by selectively exciting either the CdSe or the PbSe domains. Upon excitation of the CdSe domain sub-picosecond hole transfer to the hybrid interfacial PbSe states were identified. On the other hand, the transfer of hot electron from PbSe to CdSe was evident upon creation of hot electrons in PbSe domain without exciting the CdSe domain. The photo-excited hot hole also gets transferred to the hybrid interfacial states in sub-ps time (~1ps) bleaching the corresponding transition. The decay of the localized hole was found to be much slower compared to the electron which can be beneficial for carrier extraction and multiexciton generation. The finding of hot electron transfer in a single structure and slow decay of holes can thus prove to be advantageous for future design of photovoltaic devices.
关键词： carrier dynamics,ultrafast transient absorption spectroscopy,CdSe/PbSe Janus hetero-nanocrystals,photovoltaic devices,hot electron transfer
更新于2025-09-10 09:29:36