Giulia Tagliabue

École Polytechnique Fédérale de Lausanne | EPFL · Institute of Mechanical Engineering

Harnessing photoexcited "hot" carriers in metallic nanostructures could define a new phase of non-equilibrium optoelectronics for photodetection and photocatalysis. Surface plasmons are considered pivotal for enabling efficient operation of hot carrier devices. Clarifying the fundamental role of plasmon excitation is therefore critical for exploiti...

A fundamental understanding of hot-carrier dynamics in photo-excited metal nanostructures is needed to unlock their potential for photodetection and photocatalysis. Despite numerous studies on the ultrafast dynamics of hot electrons, so far, the temporal evolution of hot holes in metal–semiconductor heterostructures remains unknown. Here, we report...

Photo-modulation is a promising strategy for contactless and ultrafast control of optical and electrical properties of photoactive materials. Graphene is an attractive candidate material for photo-modulation due to its extraordinary physical properties and its relevance to a wide range of devices, from photodetectors to energy converters. In this r...

Reconfigurable metalenses are compact optical components composed by arrays of meta-atoms that offer unique opportunities for advanced optical systems, from microscopy to augmented reality platforms. Although poorly explored in the context of reconfigurable metalenses, thermo-optical effects in resonant silicon nanoresonators have recently emerged...

Bessel Beams (BBs) and BB lattices are structured-light excitation profiles frequently applied in material processing, nonlinear spectroscopy and in many fluorescence microscopy methods such as Light Sheet Microscopy (LSM). In LSM, BBs and BB-lattices offer wider excitation profiles, higher acquisition rate, enhanced resolution, and improved signal...

Solar powered redox cells (SPRCs) are promising for large-scale and long-term storage of solar-energy, particularly when coupled with redox flow batteries (RFBs). While efforts have primarily focused on heterostructure engineering, the potential of synergistic morphology and photonic design has not been carefully studied. Here, we investigate the w...

Thermonanophotonics, i.e. the study of photothermal effects in optical nanoantennas, has recently attracted growing interest. While thermoplasmonic structures enable a broad range of applications, from imaging and optofluidics devices to medical and photochemical systems, dielectric nanoantennas open new opportunities for thermo-optical modulation...

Optoelectronic tunability in van der Waals heterostructures is essential for their optoelectronic applications. In this work, tunable photoconductive properties were investigated in the heterostructures of WSe2 and monolayer graphene with different stacking orders on SiO2/Si substrates. Here, we demonstrated the effect of the material thickness of...

In this study, we perform a systematic investigation of the plasmonic effects of Ag and Au nanoparticles of various geometries to tune and even enhance the fluorescence intensity of single-stranded DNA-wrapped SWCNTs (ssDNA- SWCNTs). We observe a chirality-dependent NIR fluorescence enhancement that varies with both nanoparticle shape and material,...

Plasmonic nanojunctions, consisting of adjacent metal structures with nanometre gaps, can support localised plasmon resonances that boost light matter interactions and concentrate electromagnetic fields at the nanoscale. In this regime, the optical response of the system is governed by poorly understood dynamical phenomena at the frontier between t...

The use of nanoplasmonics to control light and heat close to the thermodynamic limit enables exciting opportunities in the field of plasmonic catalysis. The decay of plasmonic excitations creates highly nonequilibrium distributions of hot carriers that can initiate or catalyze reactions through both thermal and nonthermal pathways. In this Perspect...

The near-infrared emissions of single-walled carbon nanotubes (SWCNTs) falls within the optical transparency window of biological tissue, allowing deep-tissue, in vivo and in vitro imaging. However, the relatively low photoluminescence quantum yield of SWCNTs, which typically lies in the range of 0.1 - 1.5%, limits the penetration depth and sensiti...

Dielectric nanoresonators uniquely support both magnetic and electric resonances across a wide wavelength range. They are thus being exploited in a growing number of groundbreaking applications. In particular, they have been recently suggested as promising nanoheaters. However, while the thermo-optical properties of silicon and germanium resonators...

Among plasmonic metals, copper (Cu) has great potential for realizing optoelectronic and photoelectrochemical hot carrier devices, owing to its CMOS compatibility and catalytic ability for electrochemical carbon dioxide reduction. Yet, copper hot carrier dynamics have received little attention and the fundamental properties of photoexcited carriers...

We report the light-induced modification of catalytic selectivity for photoelectrochemical CO2 reduction in aqueous media using copper nanoparticles dispersed onto p-type nickel oxide photocathodes. Optical excitation of Cu nanoparticles generates hot electrons available for driving CO2 reduction on the Cu surface while charge separation is accompl...

Zero reflection and complete light absorption are required in a wide range of applications ranging from sensing devices to solar heaters and photoelectrodes. However, simultaneously satisfying the requirements of broadband spectrum, omni-directionality, polarization insensitivity, and scalability is very challenging. Combining the light-trapping ch...

Transport of charged carriers in regimes of strong non-equilibrium is critical in a wide array of applications ranging from solar energy conversion and semiconductor devices to quantum information. Plasmonic hot-carrier science brings this regime of transport physics to the forefront since photo-excited carriers must be extracted far from equilibri...

Plasmonic-metal nanostructures offer unique opportunities for solar photocatalysis via photo-excitation of highly energetic "hot" carriers at both metal-semiconductor and metal-electrolyte interfaces that can drive photochem. reactions. While examples of hot-electron-driven processes have been widely reported, little is known about the nature of pl...

Rapid advances in image sensor technology have generated a mismatch between the small size of image sensor pixels and the achievable filter spectral resolution. This mismatch has prevented the realization of chip-based image sensors with simultaneously high spatial and spectral resolution. We report here a concept that overcomes this tradeoff, enab...

Photoelectrochemical, photoelectrical and ultra-fast pump-probe studies elucidate the generation and dynamics of plasmonic hot-holes and suggest new opportunities for hot-carrier optoelectronic devices

Electrochemical conversion of CO2 into useful chemicals is a promising approach for transforming CO2 into sustainably produced fuels and/or chemical feedstocks for industrial synthesis. We report that nanoporous gold (np-Au) films, with pore sizes ranging from 10 nm to 30 nm, represent promising electrocatalytic architectures for the CO2 reduction...

Low-intensity high-temperature solar cells that operate effectively in the atmosphere of Venus at various altitudes and also survive on the 465 °C surface of Venus are being developed. Thermal stability, high-temperature current–voltage ( I–V ), and external quantum efficiency measurements on GaInP/GaAs double-junction solar cells are presented. S...

Low-intensity high-temperature (LIHT) solar cells that can function and operate effectively in the Venus atmosphere at various altitudes and also survive on the 465°C surface of Venus are being developed. Thermal, high-temperature current-voltage, and external quantum efficiency (EQE) measurements are presented on GaInP/GaAs double-junction (2J) so...

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Harvesting non-equilibrium hot carriers from plasmonic-metal nanostructures offers unique opportunities for driving photochemical reactions at the nanoscale. While examples of hot electron-driven processes abound, the realization of plasmonic systems capable of harvesting hot holes from metal nanostructures has eluded the nascent field of plasmonic...

We report experimental measurements for ultrathin (<15 nm) van der Waals heterostructures exhibiting external quantum efficiencies exceeding 50% and show that these structures can achieve experimental absorbance >90%. By coupling electromagnetic simulations and experimental measurements, we show that pn WSe2/MoS2 heterojunctions with vertical carri...

Artificial photosynthesis requires a material system that can harvest sunlight, carbon dioxide (CO_2), and water to produce chem. products (e.g. ethanol) in a solar-to-fuel process analogous to that employed by photosynthetic plants. Despite much promise, current CO_2-redn. catalysts require significant electrochem. overpotentials to achieve adequa...

Light detection and quantification is fundamental to the functioning of a broad palette of technologies. While expensive avalanche photodiodes and superconducting bolometers are examples of detectors achieving single-photon sensitivity and time resolutions down to the picosecond range, thermoelectric-based photodetectors are much more affordable al...

We demonstrate near unity, broadband absorbing optoelectronic devices using sub-15 nm thick transition metal dichalcogenides (TMDCs) of molybdenum and tungsten as van der Waals semiconductor active layers. Specifically, we report that near-unity light absorption is possible in extremely thin (< 15 nm) Van der Waals semiconductor structures by coupl...

Gap-plasmons (GP) in metal-insulator-metal (MIM) structures have shown exceptional performance in guiding and concentrating light within deep subwavelength layers. Reported designs to date exploit tapered thicknesses of the insulating layer in order to confine and focus the GP mode. Here, we propose a mechanism for the three dimensional concentrati...

In-situ assembly of high thermal conductivity materials in severely confined spaces is an important problem bringing with it scientific challenges, but also significant application relevance. Here we present a simple, affordable and reproducible methodology for synthesizing such materials, composed of hierarchical diamond micro-/nanoparticle scaffo...

Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, th...

Nanostructured metal-insulator-metal (MIM) metasurfaces supporting gap-plasmons (GPs) show great promise due to their ability to manipulate or concentrate light at the nanoscale, which is of importance to a broad palette of technologies. The interaction between individual, proximal GP nanoresonators, reaching the point of first electrical connectio...

Plasmonic nano-structures of d10 metals are suggested to be the future of photo-voltaics and photo-catalysis under solar irradiation, thanks to their large light absorption cross-section, versatility, and stability. We investigated the impact of continuous plasmon excitation at 532 nm on the density of states of gold nanoparticles, and found an inc...

Plasmonic absorbers have recently become important for a broad spectrum of sunlight-harvesting applications exploiting either heat generation, such as in thermal photovoltaics and solar thermoelectrics, or hot-electron generation, such as in photochemical and solid state devices. So far, despite impressive progress, combining the needed high perfor...

A micro particle shadow velocimetry (μPSV) system based on back-lit illumination and forward scatter observation of light from non-fluorescent particles has been developed. Relatively high luminous efficiencies and particle image contrasts were achieved by using the condenser stage of a standard transmitted light microscope and a continuous incoher...