Publications

@article{,

title = {Ultrawideband Surface Enhanced Raman Scattering in Hybrid Graphene Fragmented-Gold Substrates via Cold-Etching},

author = {T Wu and K Li and N Zhang and J Xia and Q Zeng and X Wen and U S Dinish and M Olivo and Z Shen and Z Liu and Q Xiong and Y Luo and S A Maier and L Wei},

url = {https://doi.org/10.1002/adom.201900905},

doi = {10.1002/adom.201900905},

issn = {2195-1071},

year  = {2019},

date = {2019-08-08},

journal = {Advanced Optical Materials},

volume = {0},

number = {0},

pages = {1900905},

abstract = {Abstract Conventional surface enhanced Raman scattering (SERS) substrates are well known for their supreme electromagnetic enhancements and ultrahigh sensitivity in detecting molecules at low concentrations. However, large-area quasi-uniform SERS substrates are difficult to achieve by standard top-down nanofabrication techniques, resulting in fluctuant SERS responses and unwanted fluorescence interferences, which severely limit their performances in practical applications. To tackle these challenges, a large-scale quasi-uniform hybrid graphene fragmented-gold substrate with stable and reproducible SERS readouts as well as large enhancement factors over an ultrawideband spectrum is developed. The hybrid substrate is fabricated via cold-etching through a controllable break up of a thin gold film followed by a graphene transfer. The stimulated localized surface plasmons interact strongly with the graphene layer, leading to spectrally and spatially modified graphene-mediated surface enhanced Raman scattering (GSERS) responses. The perfect monolayer graphene of the GSERS substrate prevents adsorbates from the atmosphere and direct contact between bonded molecules and gold, thus reducing the catalytic activity of gold and producing clean, stable, and reproducible molecular Raman signals. The easy-fabricated hybrid GSERS substrate not only provides a powerful platform to collect robust molecular Raman spectra but also shows great potentials for future mass production of high-performance nanophotonic devices.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Ultracompact Photodetection in Atomically Thin MoSe2},

author = {M Blauth and G Vest and S L Rosemary and M Prechtl and O Hartwig and M Jurgensen and M Kaniber and A V Stier and J J Finley},

url = {\<Go to ISI\>://WOS:000482545400012},

doi = {10.1021/acsphotonics.9b00785},

issn = {2330-4022},

year  = {2019},

date = {2019-07-30},

journal = {Acs Photonics},

volume = {6},

number = {8},

pages = {1902-1909},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Polymer Nanoreactors Shield Perovskite Nanocrystals from Degradation},

author = {V A Hintermayr and C Lampe and M Low and J Roemer and W Vanderlinden and M Gramlich and A X Bohm and C Sattler and B Nickel and T Lohmuller and A S Urban},

url = {\<Go to ISI\>://WOS:000481563800015},

doi = {10.1021/acs.nanolett.9b00982},

issn = {1530-6984},

year  = {2019},

date = {2019-07-19},

journal = {Nano Letters},

volume = {19},

number = {8},

pages = {4928-4933},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The fast and the furious: Ultrafast hot electrons in plasmonic metastructures. Size and structure matter},

author = {L V Besteiro and P Yu and Z M Wang and A W Holleitner and G V Hartland and G P Wiederrecht and A O Govorov},

url = {\<Go to ISI\>://WOS:000482526300011},

doi = {10.1016/j.nantod.2019.05.006},

issn = {1748-0132},

year  = {2019},

date = {2019-07-18},

journal = {Nano Today},

volume = {27},

pages = {120-145},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Temperature-Dependent Ambipolar Charge Carrier Mobility in Large-Crystal Hybrid Halide Perovskite Thin Films},

author = {A Biewald and N Giesbrecht and T Bein and P Docampo and A Hartschuh and R Ciesielski},

url = {https://doi.org/10.1021/acsami.9b04592},

doi = {10.1021/acsami.9b04592},

issn = {1944-8244},

year  = {2019},

date = {2019-06-12},

journal = {ACS Applied Materials \& Interfaces},

volume = {11},

number = {23},

pages = {20838-20844},

abstract = {Perovskite-based thin-film solar cells today reach power conversion efficiencies of more than 22%. Methylammonium lead iodide (MAPI) is prototypical for this material class of hybrid halide perovskite semiconductors and at the focal point of interest for a growing community in research and engineering. Here, a detailed understanding of the charge carrier transport and its limitations by underlying scattering mechanisms is of great interest to the material’s optimization and development. In this article, we present an all-optical study of the charge carrier diffusion properties in large-crystal MAPI thin films in the tetragonal crystal phase from 170 K to room temperature. We probe the local material properties of individual crystal grains within a MAPI thin film and find a steady decrease of the charge carrier diffusion constant with increasing temperature. From the resulting charge carrier mobility, we find a power law dependence of μ ∝ Tm with m = −(1.8 ± 0.1). We further study the temperature-dependent mobility of the orthorhombic crystal phase from 50 to 140 K and observe a distinctly different exponent of m = −(1.2 ± 0.1).},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Oriented Thin Films of Electroactive Triphenylene Catecholate-Based Two-Dimensional Metal\textendashOrganic Frameworks},

author = {A M\"{a}hringer and A C Jakowetz and J M Rotter and B J Bohn and J K Stolarczyk and J Feldmann and T Bein and D D Medina},

url = {https://doi.org/10.1021/acsnano.9b01137},

doi = {10.1021/acsnano.9b01137},

issn = {1936-0851},

year  = {2019},

date = {2019-05-02},

journal = {ACS Nano},

volume = {13},

number = {6},

pages = {6711-6719},

abstract = {Two-dimensional triphenylene-based metal\textendashorganic frameworks (TP-MOFs) attract significant scientific interest due to their long-range order combined with significant electrical conductivity. The deposition of these structures as oriented films is expected to promote their incorporation into diverse optoelectronic devices. However, to date, a controlled deposition strategy applicable for the different members of this MOF family has not been reported yet. Herein, we present the synthesis of highly oriented thin films of TP-MOFs by vapor-assisted conversion (VAC). We targeted the M-CAT-1 series comprising hexahydroxytriphenylene organic ligands and metal-ions such as Ni2+, Co2+, and Cu2+. These planar organic building blocks are connected in-plane to the metal-ions through a square planar node forming extended sheets which undergo self-organization into defined stacks. Highly oriented thin Ni- and Co-CAT-1 films grown on gold substrates feature a high surface coverage with a uniform film topography and thickness ranging from 180 to 200 nm. The inclusion of acid modulators in the synthesis enabled the growth of films with a preferred orientation on quartz and on conductive substrates such as indium-doped tin oxide (ITO). The van der Pauw measurements performed across the M-CAT-1 films revealed high electrical conductivity values of up to 10\textendash3 S cm\textendash1 for both the Ni- and Co-CAT-1 films. Films grown on quartz allowed for a detailed photophysical characterization by means of UV\textendashvis, photoluminescence, and transient absorption spectroscopy. The latter revealed the existence of excited states on a nanosecond time scale, sufficiently long to demonstrate a photoinduced charge generation and extraction in Ni-CAT-1 films. This was achieved by fabricating a basic photovoltaic device with an ITO/Ni-CAT-1/Al architecture, thus establishing this MOF as a photoactive material. Our results point to the intriguing capabilities of these conductive M-CAT-1 materials and an additional scope of applications as photoabsorbers enabled through VAC thin-film synthesis.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Monitoring the morphological evolution in mixed-dimensional lead bromide perovskite films with lamellar-stacked perovskite nanoplatelets},

author = {R Wang and Y Tong and K Wang and S Xia and E Kentzinger and O Soltwedel and P M\"{u}ller-Buschbaum and H Frielinghaus},

url = {http://dx.doi.org/10.1039/C9NH00156E},

doi = {10.1039/C9NH00156E},

issn = {2055-6756},

year  = {2019},

date = {2019-04-23},

journal = {Nanoscale Horizons},

volume = {4},

number = {5},

pages = {1139-1144},

abstract = {Mixed-dimensional lead bromide perovskite films combine the properties of both three-dimensional (3D) and two-dimensional (2D) perovskite crystals, and due to their good humidity tolerance, they emerge as promising candidates for long-term stable optoelectronic applications. In order to further tailor the film morphology aiming for a better device performance, it is important to unravel the structural formation mechanism in these perovskite thin films. In the present study, the formation of 3D lead bromide perovskite crystals and the self-assembly of lamellar-stacked 2D perovskite nanoplatelets are comprehensively studied. Samples are prepared through a two-step vapor assisted route with different vapor exposure times in order to monitor the detailed morphology at the specific reaction stage. With grazing incidence X-ray scattering techniques, the preferential orientation of the 3D crystals is found to decrease upon increasing the reaction time. Also, it is evidenced that well-ordered in-plane lamellar-stacked 2D nanoplatelets form aggregates in the bulk structure only. The obtained hierarchical morphology shows excellent structural stability in a humid atmosphere even at a relative humidity level of 80%. Our findings statistically offer a morphological understanding, which is important for the optimization of the sample preparation route and thus the resulting performance of moisture-tolerant perovskite based optoelectronic devices.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Identifying and Reducing Interfacial Losses to Enhance Color-Pure Electroluminescence in Blue-Emitting Perovskite Nanoplatelet Light-Emitting Diodes},

author = {R L Z Hoye and M L Lai and M Anaya and Y Tong and K Galkowski and T Doherty and W W Li and T N Huq and S Mackowski and L Polavarapu and J Feldmann and J L Macmanus-Driscoll and R H Friend and A S Urban and S D Stranks},

url = {\<Go to ISI\>://WOS:000468015600025},

doi = {10.1021/acsenergylett.9b00571},

issn = {2380-8195},

year  = {2019},

date = {2019-04-17},

journal = {Acs Energy Letters},

volume = {4},

number = {5},

pages = {1181-1188},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Tuning the optical bandgap in layered hybrid perovskites through variation of alkyl chain length},

author = {J A Sichert and A Hemmerling and C Cardenas-Daw and A S Urban and J Feldmann},

url = {\<Go to ISI\>://WOS:000466615300017},

doi = {10.1063/1.5087296},

issn = {2166-532X},

year  = {2019},

date = {2019-04-16},

journal = {Apl Materials},

volume = {7},

number = {4},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Structure and Charge Carrier Dynamics in Colloidal PbS Quantum Dot Solids},

author = {W Chen and J L Zhong and J Z Li and N Saxena and L P Kreuzer and H C Liu and L Song and B Su and D Yang and K Wang and J Schlipf and V Korstgens and T C He and K Wang and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000466991300006},

doi = {10.1021/acs.jpclett.9b00869},

issn = {1948-7185},

year  = {2019},

date = {2019-04-09},

urldate = {2019-04-09},

journal = {Journal of Physical Chemistry Letters},

volume = {10},

number = {9},

pages = {2058-2065},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Spectral Screening of the Energy of Hot Holes over a Particle Plasmon Resonance},

author = {E Pensa and J Gargiulo and A Lauri and S Schl\"{u}cker and E Cort\'{e}s and S A Maier},

url = {https://doi.org/10.1021/acs.nanolett.8b04950},

doi = {10.1021/acs.nanolett.8b04950},

issn = {1530-6984},

year  = {2019},

date = {2019-03-13},

journal = {Nano Letters},

volume = {19},

number = {3},

pages = {1867-1874},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Quantifying Figures of Merit for Localized Surface Plasmon Resonance Applications: A Materials Survey},

author = {B Doiron and M Mota and M P Wells and R Bower and A Mihai and Y Li and L F Cohen and N M Alford and P K Petrov and R F Oulton and S A Maier},

url = {https://doi.org/10.1021/acsphotonics.8b01369},

doi = {10.1021/acsphotonics.8b01369},

year  = {2019},

date = {2019-02-20},

journal = {ACS Photonics},

volume = {6},

number = {2},

pages = {240-259},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Tuning the Fr\"{o}hlich exciton-phonon scattering in monolayer MoS2},

author = {B Miller and J Lindlau and M Bommert and A Neumann and H Yamaguchi and A W Holleitner and A H\"{o}gele and U Wurstbauer},

url = {https://doi.org/10.1038/s41467-019-08764-3},

doi = {10.1038/s41467-019-08764-3},

issn = {2041-1723},

year  = {2019},

date = {2019-02-18},

journal = {Nature Communications},

volume = {10},

number = {1},

pages = {807},

abstract = {Charge carriers in semiconducting transition metal dichalcogenides possess a valley degree of freedom that allows for optoelectronic applications based on the momentum of excitons. At elevated temperatures, scattering by phonons limits valley polarization, making a detailed knowledge about strength and nature of the interaction of excitons with phonons essential. In this work, we directly access exciton-phonon coupling in charge tunable single layer MoS2 devices by polarization resolved Raman spectroscopy. We observe a strong defect mediated coupling between the long-range oscillating electric field induced by the longitudinal optical phonon in the dipolar medium and the exciton. This so-called Fr\"{o}hlich exciton phonon interaction is suppressed by doping. The suppression correlates with a distinct increase of the degree of valley polarization up to 20% even at elevated temperatures of 220 K. Our result demonstrates a promising strategy to increase the degree of valley polarization towards room temperature valleytronic applications.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Exciton Diffusion Lengths and Dissociation Rates in CsPbBr3 Nanocrystal\textendashFullerene Composites: Layer-by-Layer versus Blend Structures},

author = {E-P Yao and B J Bohn and Y Tong and H Huang and L Polavarapu and J Feldmann},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201801776},

doi = {10.1002/adom.201801776},

issn = {2195-1071},

year  = {2019},

date = {2019-02-18},

journal = {Advanced Optical Materials},

volume = {7},

number = {8},

pages = {1801776},

abstract = {Abstract Solution-processable perovskite nanocrystals (NCs) are gaining increasing interest in the field of photovoltaics because of their enhanced stability compared to their thin-film counterparts. However, the charge transfer dynamics in perovskite NC based light-harvesting systems are not well understood. By applying femtosecond differential transmission (DT) spectroscopy the photoinduced charge transfer from inorganic perovskite CsPbBr3 NCs to the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is investigated for two fundamentally different architectures, namely layer-by-layer heterostructures and blend structures. By varying the thickness of the NC layer on top of the PCBM in the layer-by-layer heterostructure, an exciton diffusion length of 290 ± 28 nm for CsPbBr3 NC is extracted. The diffusion process is followed by an ultrafast exciton dissociation (within 200 fs) at the CsPbBr3 NC/PCBM interface. In blend structures an overall faster charge transfer process is observed. Furthermore, photoconductivity measurements on a blend structure-based photodetector reveal an effective charge extraction from the active layer resulting in a high photosensitivity. DT measurements on this blend structure including adjacent electron- or hole-transport layers give insight into the extraction process and suggest a certain degree of phase segregation, which assists the charge collection.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},

author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},

url = {https://doi.org/10.1021/acs.nanolett.8b04612},

doi = {10.1021/acs.nanolett.8b04612},

issn = {1530-6984},

year  = {2019},

date = {2019-02-13},

journal = {Nano Letters},

volume = {19},

number = {2},

pages = {1172-1178},

abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},

author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},

url = {https://doi.org/10.1021/acs.nanolett.8b04612},

doi = {10.1021/acs.nanolett.8b04612},

issn = {1530-6984},

year  = {2019},

date = {2019-02-13},

journal = {Nano Letters},

volume = {19},

number = {2},

pages = {1172-1178},

abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler},

author = {T Wu and Y Luo and S A Maier and L Wei},

url = {https://link.aps.org/doi/10.1103/PhysRevApplied.11.014049},

doi = {10.1103/PhysRevApplied.11.014049},

year  = {2019},

date = {2019-01-24},

journal = {Physical Review Applied},

volume = {11},

number = {1},

pages = {014049},

abstract = {Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Probing the micro- and nanoscopic properties of dental materials using infrared spectroscopy: A proof-of-principle study},

author = {M Beddoe and T G\"{o}lz and M Barkey and E Bau and M Godejohann and S A Maier and F Keilmann and M Moldovan and D Prodan and N Ilie and A Tittl},

url = {https://www.sciencedirect.com/science/article/pii/S1742706123004026},

doi = {https://doi.org/10.1016/j.actbio.2023.07.017},

issn = {1742-7061},

journal = {Acta Biomaterialia},

volume = {168},

pages = {309-322},

abstract = {The preservation of oral health over a person's lifespan is a key factor for a high quality of life. Sustaining oral health requires high-end dental materials with a plethora of attributes such as durability, non-toxicity and ease of application. The combination of different requirements leads to increasing miniaturization and complexity of the material components such as the composite and adhesives, which makes the precise characterization of the material blend challenging. Here, we demonstrate how modern IR spectroscopy and imaging from the micro- to the nanoscale can provide insights on the chemical composition of the different material sections of a dental filling. We show how the recorded IR-images can be used for a fast and non-destructive porosity determination of the studied adhesive. Furthermore, the nanoscale study allows precise assessment of glass cluster structures and distribution within their characteristic organically modified ceramic (ORMOCER) matrix and an assessment of the interface between the composite and adhesive material. For the study we used a Fourier-Transform-IR (FTIR) microscope and a quantum cascade laser-based IR-microscope (QCL-IR) for the microscale analysis and a scattering-type scanning near-field optical microscopy (s-SNOM) for the nanoscale analysis. The paper ends with an in-depth discussion of the strengths and weaknesses of the different imaging methods to give the reader a clear picture for which scientific question the microscopes are best suited for. Statement of significance Modern resin-based composites for dental restoration are complex multi-compound materials. In order to improve these high-end materials, it is important to investigate the molecular composition and morphology of the different parts. An emergent method to characterize these materials is infrared spectroscopic imaging, which combines the strength of infrared spectroscopy and an imaging approach known from optical microscopy. In this work, three state of the art methods are compared for investigating a dental filling including FTIR- and quantum cascade laser IR-imaging microscopy for the microscale and scattering-type scanning near-field optical microscopy for the nanoscale.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Optimization of p-Type Cu2O Nanocube Photocatalysts Based on Electronic Effects},

author = {R Lin and H Chen and T Cui and Z Zhang and Q Zhou and L Nan and W-C Cheong and L Schr\"{o}ck and V Ramm and Q Ding and X Liang and S Saris and F J Wendisch and S A Maier and R A Fischer and Y Zhu and D Wang and E Cortes},

url = {https://doi.org/10.1021/acscatal.3c02710},

doi = {10.1021/acscatal.3c02710},

journal = {ACS Catalysis},

pages = {11352-11361},

abstract = {The size effect in semiconductor photocatalysis has been widely investigated but still remains elusive. Herein, employing p-type Cu2O nanocubes as the heterogeneous photocatalysts, we propose a feasible size optimization strategy to enhance the photocatalytic performance of semiconductors. With the size of Cu2O increasing from 2.5 nm (exciton Bohr radius) to 5 nm (twice the exciton Bohr radius), the corresponding calculated band gap of Cu2O decreases from 3.39 to 2.41 eV, indicating that controlling the size to above twice the exciton Bohr radius is vital for retaining the visible-light response of Cu2O. Based on the theoretical calculations and experimental measurements of the charge carrier dynamics, we found that the synthesized 30 nm Cu2O nanocubes have an electron diffusion length of 191 nm, while 229 nm Cu2O nanocubes show an electron diffusion length of 45 nm. An electron diffusion length larger than the semiconductor particle size lowers the electron\textendashhole recombination, resulting in a visible-light CO generation rate 23.4 times higher for the smaller Cu2O nanocubes than that for the larger ones. These results verify that confining Cu2O size to within the minority carrier diffusion length and above twice the exciton Bohr radius is a promising way to enhance Cu2O photocatalytic activity.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Fine-Tuning Blue-Emitting Halide Perovskite Nanocrystals},

author = {S Martin and N A Henke and C Lampe and M D\"{o}blinger and K Frank and P Ganswindt and B Nickel and A S Urban},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202301009},

doi = {https://doi.org/10.1002/adom.202301009},

issn = {2195-1071},

journal = {Advanced Optical Materials},

volume = {n/a},

number = {n/a},

pages = {2301009},

abstract = {Abstract Lead halide perovskite nanocrystals (NCs) with narrow, bright emission in the visible range are promising candidates for light-emitting applications. Near-unity quantum yields have been realized for green and red-emitting perovskites, but efficient, stable blue-emitting perovskite materials are scarce. Current methods to synthesize quantum-confined CsPbBr3 NCs with blue emission are limited to specific wavelength ranges and still suffer from inhomogeneously broadened emission profiles. Herein, anisotropic blue-green emitting CsPbBr3 NCs are synthesized in ambient atmosphere using a spontaneous crystallization method. Optical spectroscopy reveals a gradual, asymptotic photoluminescence (PL) redshift of pristine colloidal NCs after synthesis. During this process, the emission quality improves notably as the PL spectra become narrower and more symmetric, accompanied by a PL intensity increase. Electron microscopy indicates that the gradual redshift stems from an isotropic growth of the CsPbBr3 NCs in at least two dimensions, likely due to residual precursor ions in the dispersion. Most importantly, the growth process can be halted at any point by injecting an enhancement solution containing PbBr2 and organic capping ligands. Thus, excellent control over NC size is achieved, allowing for nanometer-precise tunability of the respective emission wavelength in the range between 475 and 500 nm, enhancing the functionality of these already impressive NCs.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Intrinsic strong light-matter coupling with self-hybridized bound states in the continuum in van der Waals metasurfaces},

author = {T Weber and L K\"{u}hner and L Sortino and A Ben Mhenni and N P Wilson and J K\"{u}hne and J J Finley and S A Maier and A Tittl},

url = {https://doi.org/10.1038/s41563-023-01580-7},

doi = {10.1038/s41563-023-01580-7},

issn = {1476-4660},

journal = {Nature Materials},

volume = {22},

number = {8},

pages = {970-976},

abstract = {Photonic bound states in the continuum (BICs) provide a standout platform for strong light-matter coupling with transition metal dichalcogenides (TMDCs) but have so far mostly been implemented as traditional all-dielectric metasurfaces with adjacent TMDC layers, incurring limitations related to strain, mode overlap and material integration. Here, we demonstrate intrinsic strong coupling in BIC-driven metasurfaces composed of nanostructured bulk tungsten disulfide (WS2) and exhibiting resonances with sharp, tailored linewidths and selective enhancement of light-matter interactions. Tuning of the BIC resonances across the exciton resonance in bulk WS2 is achieved by varying the metasurface unit cells, enabling strong coupling with an anticrossing pattern and a Rabi splitting of 116 meV. Crucially, the coupling strength itself can be controlled and is shown to be independent of material-intrinsic losses. Our self-hybridized metasurface platform can readily incorporate other TMDCs or excitonic materials to deliver fundamental insights and practical device concepts for polaritonic applications.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Continuous spectral and coupling-strength encoding with dual-gradient metasurfaces},

author = {A Aigner and T Weber and A Wester and S A Maier and A Tittl},

url = {https://arxiv.org/abs/2312.05600},

doi = {https://doi.org/10.48550/arXiv.2312.05600},

journal = {arXiv preprint arXiv:2312.05600},

abstract = {Optical metasurfaces excel at enhancing and controlling light-matter interactions, which are primarily dictated by two factors: the spectral overlap of the resonances with target excitations in the material and the coupling-strength between them, where resonance linewidth and localized field enhancement are the governing influences. Current metasurface designs are limited to sampling a few discrete points within this vast 2D interaction parameter space or have varied only a single parameter. Symmetry-protected bound states in the continuum (BICs) allow precise control over the wavelength and linewidth of individual resonances, but rely on large arrangements of identical unit cells, limiting the continuous mapping of the parameter space. Therefore, optical platforms that concurrently probe the spectral and coupling parameters, so far, remained elusive. Here, we introduce the concept of dual-gradient metasurfaces for the continuous and simultaneous encoding of the spectral and coupling-strength of light-matter interactions, enabled by smooth local variations of the unit cell parameters. Contrary to conventional understanding, we demonstrate that BICs can be excited in such non-periodic systems provided the parameter variations are sufficiently small. Our dual-gradient metasurface exhibits an extraordinary resonance density, with each unit cell supporting a unique mode. This results in up to 27,500 distinct modes, all contained within a compact footprint. We apply this technology to surface-enhanced molecular sensing, capturing not only the spectral fingerprint of molecules but also unveiling an additional coupling-based dimension of spectroscopic data. This advancement in metasurface design paves the way for generalized light-matter coupling with metasurfaces, with applications ranging from on-chip spectrometer, to chirality encoding and AI-driven biochemical spectroscopy.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Thermally-Induced Degradation in PM6:Y6-Based Bulk Heterojunction Organic Solar Cells},

author = {S Alam and H Aldosari and C E Petoukhoff and T V\'{a}ry and W Althobaiti and M Alqurashi and H Tang and J I Khan and V N\'{a}da\v{z}dy and P M\"{u}ller-Buschbaum and G C Welch and F Laquai},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202308076},

doi = {https://doi.org/10.1002/adfm.202308076},

issn = {1616-301X},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2308076},

abstract = {Abstract Thermally induced degradation of organic photovoltaic devices hinders the commercialization of this emerging PV technology. Thus, a precise understanding of the origin of thermal device instability, as well as identifying strategies to circumvent degradation is of utmost importance. Here, it investigates thermally-induced degradation of state-of-the-art PBDB-T-2F (PM6):BTP (Y6) bulk heterojunction solar cells at different temperatures and reveal changes of their optical properties, photophysics, and morphology. The open-circuit voltage and fill factor of thermally degraded devices are limited by dissociation and charge collection efficiency differences, while the short-circuit current density is only slightly affected. Energy-resolved electrochemical impedance spectroscopy measurements reveal that thermally degraded samples exhibit a higher energy barrier for the charge-transfer state to charge-separated state conversion. Furthermore, the field dependence of charge generation, recombination, and extraction are studied by time-delayed collection field and transient photocurrent and photovoltage experiments, indicating significant bimolecular recombination limits device performance. Finally, coupled optical-electrical device simulations are conducted to fit the devices’ current-voltage characteristics, enabling us to find useful correlations between optical and electrical properties of the active layers and device performance parameters.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Pixelated high-Q metasurfaces for in-situ biospectroscopy and AI-enabled classification of lipid membrane photoswitching dynamics},

author = {M Barkey and R B\"{u}chner and A Wester and S D Pritzl and M Makarenko and Q Wang and T Weber and D Trauner and S A Maier and A Fratalocchi},

url = {https://arxiv.org/abs/2308.15644},

doi = {https://doi.org/10.48550/arXiv.2308.15644},

journal = {arXiv preprint arXiv:2308.15644},

abstract = {Nanophotonic devices excel at confining light into intense hot spots of the electromagnetic near fields, creating unprecedented opportunities for light-matter coupling and surface-enhanced sensing. Recently, all-dielectric metasurfaces with ultrasharp resonances enabled by photonic bound states in the continuum have unlocked new functionalities for surface-enhanced biospectroscopy by precisely targeting and reading out molecular absorption signatures of diverse molecular systems. However, BIC-driven molecular spectroscopy has so far focused on endpoint measurements in dry conditions, neglecting the crucial interaction dynamics of biological systems. Here, we combine the advantages of pixelated all-dielectric metasurfaces with deep learning-enabled feature extraction and prediction to realize an integrated optofluidic platform for time-resolved in-situ biospectroscopy. Our approach harnesses high-Q metasurfaces specifically designed for operation in a lossy aqueous environment together with advanced spectral sampling techniques to temporally resolve the dynamic behavior of photoswitchable lipid membranes. Enabled by a software convolutional neural network, we further demonstrate the real-time classification of the characteristic cis and trans membrane conformations with 98% accuracy. Our synergistic sensing platform incorporating metasurfaces, optofluidics, and deep learning opens exciting possibilities for studying multi-molecular biological systems, ranging from the behavior of transmembrane proteins to the dynamic processes associated with cellular communication.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Photo-induced enhanced Raman spectroscopy as a probe for photocatalytic surfaces},

author = {S Ben-Jaber and D Glass and T Brick and S A Maier and I P Parkin and E Cort\'{e}s and W J Peveler and R Quesada-Cabrera},

url = {https://royalsocietypublishing.org/doi/abs/10.1098/rsta.2022.0343},

doi = {doi:10.1098/rsta.2022.0343},

journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},

volume = {381},

number = {2259},

pages = {20220343},

abstract = {Photo-induced enhanced Raman spectroscopy (PIERS) has emerged as a highly sensitive surface-enhanced Raman spectroscopy (SERS) technique for the detection of ultra-low concentrations of organic molecules. The PIERS mechanism has been largely attributed to UV-induced formation of surface oxygen vacancies (Vo) in semiconductor materials, although alternative interpretations have been suggested. Very recently, PIERS has been proposed as a surface probe for photocatalytic materials, following Vo formation and healing kinetics. This work establishes comparison between PIERS and Vo-induced SERS approaches in defected noble-metal-free titanium dioxide (TiO2-x) films to further confirm the role of Vo in PIERS. Upon application of three post-treatment methods (namely UV-induction, vacuum annealing and argon etching), correlation of Vo kinetics and distribution could be established. A proposed mechanism and further discussion on PIERS as a probe to explore photocatalytic materials are also presented. This article is part of the theme issue ‘Exploring the length scales, timescales and chemistry of challenging materials (Part 2)’.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Metallic and All-Dielectric Metasurfaces Sustaining Displacement-Mediated Bound States in the Continuum},

author = {L M Berger and M Barkey and S A Maier and A Tittl},

url = {https://arxiv.org/abs/2306.00591},

doi = {https://doi.org/10.48550/arXiv.2306.00591},

journal = {arXiv preprint arXiv:2306.00591},

abstract = {Bound states in the continuum (BICs) are localized electromagnetic modes within the continuous spectrum of radiating waves. Due to their infinite lifetimes without radiation losses, BICs are driving research directions in lasing, non-linear optical processes, and sensing. However, conventional methods for converting BICs into leaky resonances, or quasi-BICs, with high-quality factors typically rely on breaking the in-plane inversion symmetry of the metasurface and often result in resonances that are strongly dependent on the angle of the incident light, making them unsuitable for many practical applications. Here, we numerically analyze and experimentally demonstrate an emerging class of BIC-driven metasurfaces, where the coupling to the far field is controlled by the displacement of individual resonators. In particular, we investigate both all-dielectric and metallic as well as positive and inverse displacement-mediated metasurfaces sustaining angular-robust quasi-BICs in the mid-infrared spectral region. We explore their behavior with changes in the incidence angle of illumination and experimentally show their superior performance compared to two conventional alternatives: silicon-based tilted ellipses and cylindrical nanoholes in gold. We anticipate our findings to open exciting perspectives for bio-sensing, conformal optical devices, and photonic devices using focused light.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Spatial Distributions of Single-Molecule Reactivity in Plasmonic Catalysis},

author = {S Ezendam and J Gargiulo and A Sousa-Castillo and J B Lee and Y S Nam and S A Maier and E Cort\'{e}s},

url = {https://doi.org/10.1021/acsnano.3c07833},

doi = {10.1021/acsnano.3c07833},

issn = {1936-0851},

journal = {ACS Nano},

abstract = {Plasmonic catalysts have the potential to accelerate and control chemical reactions with light by exploiting localized surface plasmon resonances. However, the mechanisms governing plasmonic catalysis are not simple to decouple. Several plasmon-derived phenomena, such as electromagnetic field enhancements, temperature, or the generation of charge carriers, can affect the reactivity of the system. These effects are convoluted with the inherent (nonplasmonic) catalytic properties of the metal surface. Disentangling these coexisting effects is challenging but is the key to rationally controlling reaction pathways and enhancing reaction rates. This study utilizes super-resolution fluorescence microscopy to examine the mechanisms of plasmonic catalysis at the single-particle level. The reduction reaction of resazurin to resorufin in the presence of Au nanorods coated with a porous silica shell is investigated in situ. This allows the determination of reaction rates with a single-molecule sensitivity and subparticle resolution. By variation of the irradiation wavelength, it is possible to examine two different regimes: photoexcitation of the reactant molecules and photoexcitation of the nanoparticle’s plasmon resonance. In addition, the measured spatial distribution of reactivity allows differentiation between superficial and far-field effects. Our results indicate that the reduction of resazurin can occur through more than one reaction pathway, being most efficient when the reactant is photoexcited and is in contact with the Au surface. In addition, it was found that the spatial distribution of enhancements varies, depending on the underlying mechanism. These findings contribute to the fundamental understanding of plasmonic catalysis and the rational design of future plasmonic nanocatalysts.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Anti Stokes Thermometry of Plasmonic Nanoparticle Arrays},

author = {S Ezendam and L Nan and I L Violi and S A Maier and E Cort\'{e}s and G Baffou and J Gargiulo},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202301496},

doi = {https://doi.org/10.1002/adom.202301496},

issn = {2195-1071},

journal = {Advanced Optical Materials},

volume = {n/a},

number = {n/a},

pages = {2301496},

abstract = {Abstract Metallic nanoparticles possess strong photothermal responses, especially when illuminated as ensembles due to collective effects. However, accurately quantifying the temperature increase remains a significant challenge, impeding progress in several applications. Anti Stokes thermometry offers a promising solution by enabling direct and non-invasive temperature measurements of the metal without the need for labeling or prior calibration. While Anti Stokes thermometry is successfully applied to individual nanoparticles, its potential to study light-to-heat conversion with plasmonic ensembles remains unexplored. In this study, the theoretical framework and the conditions that must be fulfilled for applying Anti Stokes thermometry to ensembles of nanoparticles are discussed. Then, this technique is implemented to measure the light-induced heating of square arrays of Au nanodisks. The obtained temperature measurements are validated using wavefront microscopy, demonstrating excellent agreement between the two thermometry methods. These results showcase the extension of Anti Stokes thermometry to plasmonic ensembles, highlighting its potential for implementation in the diverse photothermal applications involving these systems.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Impact of bimetallic interface design on heat generation in plasmonic Au/Pd nanostructures studied by single-particle thermometry},

author = {J Gargiulo and M Herran and I L Violi and A Sousa-Castillo and L P Martinez and S Ezendam and M Barella and H Giesler and R Grzeschik and S Schl\"{u}cker and S A Maier and F D Stefani and E Cort\'{e}s},

url = {https://doi.org/10.1038/s41467-023-38982-9},

doi = {10.1038/s41467-023-38982-9},

issn = {2041-1723},

journal = {Nature Communications},

volume = {14},

number = {1},

pages = {3813},

abstract = {Localized surface plasmons are lossy and generate heat. However, accurate measurement of the temperature of metallic nanoparticles under illumination remains an open challenge, creating difficulties in the interpretation of results across plasmonic applications. Particularly, there is a quest for understanding the role of temperature in plasmon-assisted catalysis. Bimetallic nanoparticles combining plasmonic with catalytic metals are raising increasing interest in artificial photosynthesis and the production of solar fuels. Here, we perform single-particle thermometry measurements to investigate the link between morphology and light-to-heat conversion of colloidal Au/Pd nanoparticles with two different configurations: core\textendashshell and core-satellite. It is observed that the inclusion of Pd as a shell strongly reduces the photothermal response in comparison to the bare cores, while the inclusion of Pd as satellites keeps photothermal properties almost unaffected. These results contribute to a better understanding of energy conversion processes in plasmon-assisted catalysis.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Decoding the Self-Assembly Plasmonic Interface Structure in a PbS Colloidal Quantum Dot Solid for a Photodetector},

author = {T Guan and W Chen and H Tang and D Li and X Wang and C L Weindl and Y Wang and Z Liang and S Liang and T Xiao and S Tu and S V Roth and L Jiang and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsnano.3c08526},

doi = {10.1021/acsnano.3c08526},

issn = {1936-0851},

journal = {ACS Nano},

volume = {17},

number = {22},

pages = {23010-23019},

abstract = {Hybrid plasmonic nanostructures have gained enormous attention in a variety of optoelectronic devices due to their surface plasmon resonance properties. Self-assembled hybrid metal/quantum dot (QD) architectures offer a means of coupling the properties of plasmonics and QDs to photodetectors, thereby modifying their functionality. The arrangement and localization of hybrid nanostructures have an impact on exciton trapping and light harvesting. Here, we present a hybrid structure consisting of self-assembled gold nanospheres (Au NSs) embedded in a solid matrix of PbS QDs for mapping the interface structures and the motion of charge carriers. Grazing-incidence small-angle X-ray scattering is utilized to analyze the localization and spacing of the Au NSs within the hybrid structure. Furthermore, by correlating the morphology of the Au NSs in the hybrid structure with the corresponding differences observed in the performance of photodetectors, we are able to determine the impact of interface charge carrier dynamics in the coupling structure. From the perspective of architecture, our study provides insights into the performance improvement of optoelectronic devices.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Refining the Substrate Surface Morphology for Achieving Efficient Inverted Perovskite Solar Cells},

author = {R Guo and X Wang and X Jia and X Guo and J Li and Z Li and K Sun and X Jiang and E Alvianto and Z Shi and M Schwartzkopf and P M\"{u}ller-Buschbaum and Y Hou},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202302280},

doi = {https://doi.org/10.1002/aenm.202302280},

issn = {1614-6832},

journal = {Advanced Energy Materials},

volume = {13},

number = {43},

pages = {2302280},

abstract = {Abstract Significant advancements in perovskite solar cells (PSCs) have been driven by the engineering of the interface between perovskite absorbers and charge transport layers. Inverted PSCs offer substantial potential with their high power conversion efficiency (PCE) and enhanced compatibility for tandem solar cell applications. Conventional hole transport materials like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(triaryl amine) (PTAA) not only constrain the PSC efficiency but also elevate their fabrication costs. In the case of improving inverted structured PSCs according to the aforementioned concerns, utilizing self-assembled monolayers (SAMs) as hole-transporting layers has played a crucial role. However, the growth of self-assembled monolayers on the substrates still limits the performance and reproducibility of inverted structured PSCs. In this study, the authors delve into the growth model of SAMs on different surface morphologies. Moreover, it is found that the plasma treatment can effectively regulate the surface morphologies of substrates and achieve conformal growth of SAMs. This treatment improves the uniformity and suppresses non-radiative recombination at the interface, which leads to a PCE of 24.5% (stabilized at 23.5%) for inverted structured PSCs.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Plasmonic bimetallic two-dimensional supercrystals for H2 generation},

author = {M Herran and S Juergensen and M Kessens and D Hoeing and A K\"{o}ppen and A Sousa-Castillo and W J Parak and H Lange and S Reich and F Schulz and E Cort\'{e}s},

url = {https://doi.org/10.1038/s41929-023-01053-9},

doi = {10.1038/s41929-023-01053-9},

issn = {2520-1158},

journal = {Nature Catalysis},

volume = {6},

number = {12},

pages = {1205-1214},

abstract = {Sunlight-driven H2 generation is a central technology to tackle our impending carbon-based energy collapse. Colloidal photocatalysts consisting of plasmonic and catalytic nanoparticles are promising for H2 production at solar irradiances, but their performance is hindered by absorption and multiscattering events. Here we present a two-dimensional bimetallic catalyst by incorporating platinum nanoparticles into a well-defined supercrystal of gold nanoparticles. The bimetallic supercrystal exhibited an H2 generation rate of $$139,mathrmmmol,mathrmg_mathrmcat^-1,mathrmh^-1$$via formic acid dehydrogenation under visible light illumination and solar irradiance. This configuration makes it possible to study the interaction between the two metallic materials and the influence of this in catalysis. We observe a correlation between the intensity of the electric field in the hotspots and the boosted catalytic activity of platinum nanoparticles, while identifying a minor role of heat and gold-to-platinum charge transfer in the enhancement. Our results demonstrate the benefits of two-dimensional configurations with optimized architecture for liquid-phase photocatalysis.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Photovoltage and Photocurrent Absorption Spectra of Sulfur Vacancies Locally Patterned in Monolayer MoS2},

author = {A H\"{o}tger and W M\"{a}nner and T Amit and D Hernang\'{o}mez-P\'{e}rez and T Taniguchi and K Watanabe and U Wurstbauer and J J Finley and S Refaely-Abramson and C Kastl and A W Holleitner},

url = {https://doi.org/10.1021/acs.nanolett.3c03517},

doi = {10.1021/acs.nanolett.3c03517},

issn = {1530-6984},

journal = {Nano Letters},

abstract = {We report on the optical absorption characteristics of selectively positioned sulfur vacancies in monolayer MoS2, as observed by photovoltage and photocurrent experiments in an atomistic vertical tunneling circuit at cryogenic and room temperature. Charge carriers are resonantly photoexcited within the defect states before they tunnel through an hBN tunneling barrier to a graphene-based drain contact. Both photovoltage and photocurrent characteristics confirm the optical absorption spectrum as derived from ab initio GW and Bethe\textendashSalpeter equation approximations. Our results reveal the potential of single-vacancy tunneling devices as atomic-scale photodiodes.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Semiconductor Metasurfaces for Surface-enhanced Raman Scattering},

author = {H Hu and A K Pal and A Berestennikov and T Weber and A Stefancu and E Cortes and S A Maier and A Tittl},

url = {https://arxiv.org/abs/2309.10732},

doi = {https://doi.org/10.48550/arXiv.2309.10732},

journal = {arXiv preprint arXiv:2309.10732},

abstract = {Semiconductor-based surface-enhanced Raman spectroscopy (SERS) substrates, as a new frontier in the field of SERS, are hindered by their poor electromagnetic field confinement, and weak light-matter interaction. Metasurfaces, a class of 2D artificial materials based on the electromagnetic design of nanophotonic resonators, enable strong electromagnetic field enhancement and optical absorption engineering for a wide range of semiconductor materials. However, the engineering of semiconductor substrates into metasurfaces for improving SERS activity remains underexplored. Here, we develop an improved SERS metasurface platform that leverages the combination of titanium oxide (TiO2) and the emerging physical concept of optical bound states in the continuum (BICs) to boost the Raman emission. Moreover, fine-tuning of BIC-assisted resonant absorption offers a pathway for maximizing the photoinduced charge transfer effect (PICT) in SERS. We achieve ultrahigh values of BIC-assisted electric field enhancement (|E/E0|^2 ~ 10^3), challenging the preconception of weak electromagnetic (EM) field enhancement on semiconductor SERS substrates. Our BIC-assisted TiO2 metasurface platform offers a new dimension in spectrally-tunable SERS with earth-abundant and bio-compatible semiconductor materials, beyond the traditional plasmonic ones.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Insights into the effects of oriented crystallization on the performance of quasi-two-dimensional perovskite solar cells},

author = {R Jiang and T Tian and B Ke and Z Kou and P M\"{u}ller-Buschbaum and F Huang and Y-B Cheng and T Bu},

url = {https://www.sciencedirect.com/science/article/pii/S2949822823000448},

doi = {https://doi.org/10.1016/j.nxmate.2023.100044},

issn = {2949-8228},

journal = {Next Materials},

volume = {1},

number = {4},

pages = {100044},

abstract = {Long-term operational stability is one of the key problems for the commercialization of the perovskite photovoltaics. During the past decade, a tremendous amount of work has aimed at addressing the stability issues of perovskite solar cells (PSCs). Among them, the intrinsic instability of the ionic crystal structure of perovskite materials is foremost where proper strategies are highly required to complete the crystallization. Reducing the dimensional structure of the photoactive three-dimensional (3D) perovskites by the introduction of a non-photoactive two-dimensional (2D) perovskite phase is a rising topic recently, which generates a quasi-2D perovskite for improving the corresponding device stability. However, the power conversion efficiency (PCE) of quasi-2D perovskite solar cells decreases unfortunately with the increase of the 2D contents, which obviously depends on the orientation of the crystals. In this review, we first review the effect of the crystal orientation on the performance of quasi-2D PSCs. Then, the growth mechanism of the preferred crystal orientation is discussed in detail. The research progress of the modulation strategies which are key segments for the preferred oriented growth of quasi-2D perovskite crystals is summarized emphatically. Finally, we identify some challenges and opportunities for chasing efficient quasi-2D PSCs in furthering our understanding of the above themes.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Theory of Hot-Carrier Generation in Bimetallic Plasmonic Catalysts},

author = {H Jin and M Herran and E Cort\'{e}s and J Lischner},

url = {https://doi.org/10.1021/acsphotonics.3c00715},

doi = {10.1021/acsphotonics.3c00715},

journal = {ACS Photonics},

volume = {10},

number = {10},

pages = {3629-3636},

abstract = {Bimetallic nanoreactors in which a plasmonic metal is used to funnel solar energy toward a catalytic metal have recently been studied experimentally, but a detailed theoretical understanding of these systems is lacking. Here, we present theoretical results of hot-carrier generation rates of different Au\textendashPd nanoarchitectures. In particular, we study spherical core\textendashshell nanoparticles with a Au core and a Pd shell as well as antenna\textendashreactor systems consisting of a large Au nanoparticle that acts as an antenna and a smaller Pd satellite nanoparticle separated by a gap. In addition, we investigate an antenna\textendashreactor system in which the satellite is a core\textendashshell nanoparticle. Hot-carrier generation rates are obtained from an atomistic quantum-mechanical modeling technique which combines a solution of Maxwell’s equation with a tight-binding description of the nanoparticle electronic structure. We find that antenna\textendashreactor systems exhibit significantly higher hot-carrier generation rates in the catalytic material than the core\textendashshell system as a result of strong electric field enhancements associated with the gap between the antenna and the satellite. For these systems, we also study the dependence of the hot-carrier generation rate on the size of the gap, the radius of the antenna nanoparticle, and the direction of light polarization. Overall, we find a strong correlation between the calculated hot-carrier generation rates and the experimentally measured chemical activity for the different Au\textendashPd photocatalysts. Our insights pave the way toward a microscopic understanding of hot-carrier generation in heterogeneous nanostructures for photocatalysis and other energy-conversion applications.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tailoring Low-Dimensional Phases for Improved Performance of 2D\textendash3D Tin Perovskite Solar Cells},

author = {Z Kang and Y Tong and K Wang and Y Chen and P Yan and G Pan and P M\"{u}ller-Buschbaum and L Zhang and Y Yang and J Wu and H Xie and S Liu and H Wang},

url = {https://doi.org/10.1021/acsmaterialslett.3c00929},

doi = {10.1021/acsmaterialslett.3c00929},

journal = {ACS Materials Letters},

pages = {1-9},

abstract = {2D\textendash3D tin perovskites are considered as promising candidates for realizing efficient lead-free perovskite solar cells (PSCs). However, the ultrathin 2D phases could unfavorably affect charge transport and device performance. In the present work, we demonstrate that the introduction of D-homoserine lactone hydrochloride (D-HLH) can tailor the low-dimensional phases and improve the quality of 2D\textendash3D tin perovskite films. The functional group in D-HLH can interact with FA+ and I\textendash as well as Sn2+ in the precursor solution. These interactions not only affect the formation of tin perovskite film and favor the formation of thicker 2D phases but also decrease the defect density and suppress the nonradiative recombination. As a result, the efficiency of tin PSCs is significantly improved from 7.97 to 12.45%, and the stability of the device is also enhanced. This work provides a feasible strategy to regulate the low-dimensional phases in 2D\textendash3D tin PSCs toward realizing high efficiency.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mass transport and charge transfer through an electrified interface between metallic lithium and solid-state electrolytes},

author = {L Katzenmeier and M G\"{o}\sswein and L Carstensen and J Sterzinger and M Ederer and P M\"{u}ller-Buschbaum and A Gagliardi and A S Bandarenka},

url = {https://doi.org/10.1038/s42004-023-00923-4},

doi = {10.1038/s42004-023-00923-4},

issn = {2399-3669},

journal = {Communications Chemistry},

volume = {6},

number = {1},

pages = {124},

abstract = {All-solid-state Li-ion batteries are one of the most promising energy storage devices for future automotive applications as high energy density metallic Li anodes can be safely used. However, introducing solid-state electrolytes needs a better understanding of the forming electrified electrode/electrolyte interface to facilitate the charge and mass transport through it and design ever-high-performance batteries. This study investigates the interface between metallic lithium and solid-state electrolytes. Using spectroscopic ellipsometry, we detected the formation of the space charge depletion layers even in the presence of metallic Li. That is counterintuitive and has been a subject of intense debate in recent years. Using impedance measurements, we obtain key parameters characterizing these layers and, with the help of kinetic Monte Carlo simulations, construct a comprehensive model of the systems to gain insights into the mass transport and the underlying mechanisms of charge accumulation, which is crucial for developing high-performance solid-state batteries.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Coherent Phonons in van der Waals MoSe2/WSe2 Heterobilayers},

author = {C Li and A V Scherbakov and P Soubelet and A K Samusev and C Ruppert and N Balakrishnan and V E Gusev and A V Stier and J J Finley and M Bayer and A V Akimov},

url = {https://doi.org/10.1021/acs.nanolett.3c02316},

doi = {10.1021/acs.nanolett.3c02316},

issn = {1530-6984},

journal = {Nano Letters},

volume = {23},

number = {17},

pages = {8186-8193},

abstract = {The increasing role of two-dimensional (2D) devices requires the development of new techniques for ultrafast control of physical properties in 2D van der Waals (vdW) nanolayers. A special feature of heterobilayers assembled from vdW monolayers is femtosecond separation of photoexcited electrons and holes between the neighboring layers, resulting in the formation of Coulomb force. Using laser pulses, we generate a 0.8 THz coherent breathing mode in MoSe2/WSe2 heterobilayers, which modulates the thickness of the heterobilayer and should modulate the photogenerated electric field in the vdW gap. While the phonon frequency and decay time are independent of the stacking angle between the MoSe2 and WSe2 monolayers, the amplitude decreases at intermediate angles, which is explained by a decrease in the photogenerated electric field between the layers. The modulation of the vdW gap by coherent phonons enables a new technology for the generation of THz radiation in 2D nanodevices with vdW heterobilayers.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Transformation-Optics-Designed Plasmonic Singularities for Efficient Photocatalytic Hydrogen Evolution at Metal/Semiconductor Interfaces},

author = {T Lin and T Yang and Y Cai and J Li and G Lu and S Chen and Y Li and L Guo and S A Maier and C Liu and J Huang},

url = {https://doi.org/10.1021/acs.nanolett.3c01287},

doi = {10.1021/acs.nanolett.3c01287},

issn = {1530-6984},

journal = {Nano Letters},

volume = {23},

number = {11},

pages = {5288-5296},

abstract = {Inspired by transformation optics, we propose a new concept for plasmonic photocatalysis by creating a novel hybrid nanostructure with a plasmonic singularity. Our geometry enables broad and strong spectral light harvesting at the active site of a nearby semiconductor where the chemical reaction occurs. A proof-of-concept nanostructure comprising Cu2ZnSnS4 (CZTS) and Au\textendashAu dimer (t-CZTS@Au\textendashAu) is fabricated via a colloidal strategy combining templating and seeded growth. On the basis of numerical and experimental results of different related hybrid nanostructures, we show that both the sharpness of the singular feature and the relative position to the reactive site play a pivotal role in optimizing photocatalytic activity. Compared with bare CZTS, the hybrid nanostructure (t-CZTS@Au\textendashAu) exhibits an enhancement of the photocatalytic hydrogen evolution rate by up to ∼9 times. The insights gained from this work might be beneficial for designing efficient composite plasmonic photocatalysts for diverse photocatalytic reactions.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Near-Infrared Organic Photodetectors toward Skin-Integrated Photoplethysmography-Electrocardiography Multimodal Sensing System},

author = {Z Lou and J Tao and B Wei and X Jiang and S Cheng and Z Wang and C Qin and R Liang and H Guo and L Zhu and P M\"{u}ller-Buschbaum and H-M Cheng and X Xu},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/advs.202304174},

doi = {https://doi.org/10.1002/advs.202304174},

issn = {2198-3844},

journal = {Advanced Science},

volume = {n/a},

number = {n/a},

pages = {2304174},

abstract = {Abstract In the fast-evolving landscape of decentralized and personalized healthcare, the need for multimodal biosensing systems that integrate seamlessly with the human body is growing rapidly. This presents a significant challenge in devising ultraflexible configurations that can accommodate multiple sensors and designing high-performance sensing components that remain stable over long periods. To overcome these challenges, ultraflexible organic photodetectors (OPDs) that exhibit exceptional performance under near-infrared illumination while maintaining long-term stability are developed. These ultraflexible OPDs demonstrate a photoresponsivity of 0.53 A W−1 under 940 nm, shot-noise-limited specific detectivity of 3.4 × 1013 Jones, and cut-off response frequency beyond 1 MHz at −3 dB. As a result, the flexible photoplethysmography sensor boasts a high signal-to-noise ratio and stable peak-to-peak amplitude under hypoxic and hypoperfusion conditions, outperforming commercial finger pulse oximeters. This ensures precise extraction of blood oxygen saturation in dynamic working conditions. Ultraflexible OPDs are further integrated with conductive polymer electrodes on an ultrathin hydrogel substrate, allowing for direct interface with soft and dynamic skin. This skin-integrated sensing platform provides accurate measurement of photoelectric and biopotential signals in a time-synchronized manner, reproducing the functionality of conventional technologies without their inherent limitations.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Active Huygens' metasurface based on in-situ grown conductive polymer},

author = {W Lu and L D S Menezes and A Tittl and H Ren and S A Maier},

url = {https://arxiv.org/abs/2305.07356},

doi = {https://doi.org/10.48550/arXiv.2305.07356},

journal = {arXiv preprint arXiv:2305.07356},

abstract = {Active metasurfaces provide unique advantages for on-demand light manipulation at a subwavelength scale for emerging applications of 3D displays, augmented/virtual reality (AR/VR) glasses, holographic projectors and light detection and ranging (LiDAR). These applications put stringent requirements on switching speed, cycling duration, controllability over intermediate states, modulation contrast, optical efficiency and operation voltages. However, previous demonstrations focus only on particular subsets of these key performance requirements for device implementation, while the other performance metrics have remained too low for any practical use. Here, we demonstrate an active Huygens' metasurface based on in-situ grown conductive polymer with holistic switching performance, including switching speed of 60 frames per second (fps), switching duration of more than 2000 switching cycles without noticeable degradation, hysteresis-free controllability over intermediate states, modulation contrast of over 1400%, optical efficiency of 28% and operation voltage range within 1 V. Our active metasurface design meets all foundational requirements for display applications and can be readily incorporated into other metasurface concepts to deliver high-reliability electrical control over its optical response, paving the way for compact and robust electro-optic metadevices.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Assessment of the Degradation Mechanisms of Cu Electrodes during the CO2 Reduction Reaction},

author = {R V Mom and L-E Sandoval-Diaz and D Gao and C-H Chuang and E A Carbonio and T E Jones and R Arrigo and D Ivanov and M H\"{a}vecker and B Roldan Cuenya and R Schl\"{o}gl and T Lunkenbein and A Knop-Gericke and J-J Velasco-V\'{e}lez},

url = {https://doi.org/10.1021/acsami.2c23007},

doi = {10.1021/acsami.2c23007},

issn = {1944-8244},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {25},

pages = {30052-30059},

abstract = {Catalyst degradation and product selectivity changes are two of the key challenges in the electrochemical reduction of CO2 on copper electrodes. Yet, these aspects are often overlooked. Here, we combine in situ X-ray spectroscopy, in situ electron microscopy, and ex situ characterization techniques to follow the long-term evolution of the catalyst morphology, electronic structure, surface composition, activity, and product selectivity of Cu nanosized crystals during the CO2 reduction reaction. We found no changes in the electronic structure of the electrode under cathodic potentiostatic control over time, nor was there any build-up of contaminants. In contrast, the electrode morphology is modified by prolonged CO2 electroreduction, which transforms the initially faceted Cu particles into a rough/rounded structure. In conjunction with these morphological changes, the current increases and the selectivity changes from value-added hydrocarbons to less valuable side reaction products, i.e., hydrogen and CO. Hence, our results suggest that the stabilization of a faceted Cu morphology is pivotal for ensuring optimal long-term performance in the selective reduction of CO2 into hydrocarbons and oxygenated products.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Unraveling the Humidity Influence on the Electrical Properties of Ionic Liquid Posttreated Poly(3,4-ethylene dioxythiophene):Poly(styrenesulfonate) Films},

author = {A L Oechsle and T Sch\"{o}ner and C Geiger and S Tu and P Wang and R Cubitt and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acs.macromol.3c01842},

doi = {10.1021/acs.macromol.3c01842},

issn = {0024-9297},

journal = {Macromolecules},

volume = {56},

number = {22},

pages = {9117-9126},

abstract = {The conductive polymer blend poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), popular for numerous organic applications, is investigated in terms of the influences that ionic liquid (IL) treatment and ambient humidity have on its conductivity properties. PEDOT:PSS thin films posttreated with different concentrations of the IL 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA) are exposed to different relative humidity (RH) steps from 0% RH up to 90% RH. Simultaneously, the film swelling and increase in the scattering length density (SLD), indicating a water uptake of the films, are monitored in situ with spectral reflectance (SR) and time-of-flight neutron reflectometry (ToF-NR). Additional in situ electrochemical impedance spectroscopy (EIS) shows that the pristine PEDOT:PSS has only an electronic conductivity, while for the IL-treated samples, an additional ionic conductivity contribution is observed. Upon humidity increase, the electronic conductivity of all PEDOT:PSS thin films decreases, while the ionic conductivity for IL posttreated thin films is enhanced by the intake of water molecules.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Fast optoelectronic charge state conversion of silicon vacancies in diamond},

author = {M Rieger and V Villafane and L M Todenhagen and S Matthies and S Appel and M S Brandt and K Mueller and J J Finley},

url = {https://arxiv.org/abs/2310.12288},

doi = {https://doi.org/10.48550/arXiv.2310.12288},

journal = {arXiv preprint arXiv:2310.12288},

abstract = {Group IV vacancy color centers in diamond are promising spin-photon interfaces with strong potential for applications for photonic quantum technologies. Reliable methods for controlling and stabilizing their charge state are urgently needed for scaling to multi-qubit devices. Here, we manipulate the charge state of silicon vacancy (SiV) ensembles by combining luminescence and photo-current spectroscopy. We controllably convert the charge state between the optically active SiV− and dark SiV2− with MHz rates and 90% contrast by judiciously choosing the local potential applied to in-plane surface electrodes and the laser excitation wavelength. We observe intense SiV− photoluminescence under hole-capture, measure the intrinsic conversion time from the dark SiV2− to the bright SiV− to be 36.4(6.7)ms and demonstrate how it can be enhanced by a factor of 105 via optical pumping. Moreover, we obtain new information on the defects that contribute to photo-conductivity, indicating the presence of substitutional nitrogen and divacancies.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Large Tolerance of Lasing Properties to Impurity Defects in GaAs(Sb)-AlGaAs Core-Shell Nanowire Lasers},

author = {T Schreitm\"{u}ller and H W Jeong and H Esmaielpour and C E Mead and M Ramsteiner and P Schmiedeke and A Thurn and A Ajay and S Matich and M D\"{o}blinger and L J Lauhon and J J Finley and G Koblm\"{u}ller},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202311210},

doi = {https://doi.org/10.1002/adfm.202311210},

issn = {1616-301X},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2311210},

abstract = {Abstract GaAs-AlGaAs based nanowire (NW) lasers hold great potential for on-chip photonic applications, where lasing metrics have steadily improved over the years by optimizing resonator design and surface passivation methods. The factor that will ultimately limit the performance will depend on material properties, such as native- or impurity-induced point defects and their impact on non-radiative recombination. Here, the role of impurity-induced point defects on the lasing performance of low-threshold GaAs(Sb)-AlGaAs NW-lasers is evaluated, particularly by exploring Si-dopants and their associated vacancy complexes. Si-induced point defects and their self-compensating nature are identified using correlated atom probe tomography, resonant Raman scattering, and photoluminescence experiments. Under pulsed optical excitation the lasing threshold is remarkably low (\<10 µJ cm−2) and insensitive to impurity defects over a wide range of Si doping densities, while excess doping ([Si]\>1019 cm−3) imposes increased threshold at low temperature. These characteristics coincide with increased Shockley-Read-Hall recombination, reflected by shorter carrier lifetimes, and reduced internal quantum efficiencies (IQE) . Remarkably, despite the lower IQE the presence of self-compensating Si-vacancy defects provides an improved temperature stability in lasing threshold with higher characteristic temperature and room-temperature lasing. These findings highlight an overall large tolerance of lasing metrics to impurity defects in GaAs-AlGaAs based NW-lasers.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Optically addressable spin defects coupled to bound states in the continuum metasurfaces},

author = {L Sortino and A Gale and L K\"{u}hner and C Li and J Biechteler and F J Wendisch and M Kianinia and H Ren and M Toth and S A Maier},

url = {https://arxiv.org/abs/2306.05735},

doi = {https://doi.org/10.48550/arXiv.2306.05735},

journal = {arXiv preprint arXiv:2306.05735},

abstract = {Van der Waals (vdW) materials, including hexagonal boron nitride (hBN), are layered crystalline solids with appealing properties for investigating light-matter interactions at the nanoscale. hBN has emerged as a versatile building block for nanophotonic structures, and the recent identification of native optically addressable spin defects has opened up exciting possibilities in quantum technologies. However, these defects exhibit relatively low quantum efficiencies and a broad emission spectrum, limiting potential applications. Optical metasurfaces present a novel approach to boost light emission efficiency, offering remarkable control over light-matter coupling at the sub-wavelength regime. Here, we propose and realise a monolithic scalable integration between intrinsic spin defects in hBN metasurfaces and high quality (Q) factor resonances leveraging quasi-bound states in the continuum (qBICs). Coupling between spin defect ensembles and qBIC resonances delivers a 25-fold increase in photoluminescence intensity, accompanied by spectral narrowing to below 4 nm linewidth facilitated by Q factors exceeding 10 ^2. Our findings demonstrate a new class of spin based metasurfaces and pave the way towards vdW-based nanophotonic devices with enhanced efficiency and sensitivity for quantum applications in imaging, sensing, and light emission.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Comparison of Harmonic Generation from Crystalline and Amorphous Gallium Phosphide Nanofilms},

author = {B Tilmann and T Huq and T Possmayer and J Dranczewski and B Nickel and H Zhang and L Krivitsky and A I Kuznetsov and L De S. Menezes and S Vezzoli and R Sapienza and S A Maier},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202300269},

doi = {https://doi.org/10.1002/adom.202300269},

issn = {2195-1071},

journal = {Advanced Optical Materials},

volume = {11},

number = {16},

pages = {2300269},

abstract = {Abstract Gallium phosphide (GaP) is a promising material for nanophotonics, given its large refractive index and a transparency over most of the visible spectrum. However, since easy phase-matching is not possible with bulk GaP, a comprehensive study of its nonlinear optical properties for harmonic generation, especially when grown as thin films, is still missing. Here, second harmonic generation is studied from epitaxially grown GaP thin films, demonstrating that the absolute conversion efficiencies are comparable to a bulk wafer over the pump wavelength range from 1060 to 1370 nm. Furthermore, the results are compared to nonlinear simulations, and the second order nonlinear susceptibility is extracted, showing a similar dispersion and magnitude to that of the bulk material. Furthermore, the third order nonlinear susceptibility of amorphous GaP thin films is extracted from third harmonic generation to be more than one order of magnitude larger than that of the crystalline material, and generation of up to the fifth harmonic is reported. The results show the potential of crystalline and amorphous thin films for nonlinear optics with nanoantennas and metasurfaces, particularly in the visible to near infrared part of the spectrum.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Fluorescence enhancement in topologically optimized gallium phosphide all-dielectric nanoantennas},

author = {C Vidal and B Tilmann and S Tiwari and T Raziman and S A Maier and J Wenger and R Sapienza},

url = {https://arxiv.org/abs/2310.07309},

doi = {https://doi.org/10.48550/arXiv.2310.07309},

journal = {arXiv preprint arXiv:2310.07309},

abstract = {Nanoantennas capable of large fluorescence enhancement with minimal absorption are crucial for future optical technologies from single-photon sources to biosensing. Efficient dielectric nanoantennas have been designed, however, evaluating their performance at the individual emitter level is challenging due to the complexity of combining high-resolution nanofabrication, spectroscopy and nanoscale positioning of the emitter. Here, we study the fluorescence enhancement in infinity-shaped gallium phosphide (GaP) nanoantennas based on a topologically optimized design. Using fluorescence correlation spectroscopy (FCS), we probe the nanoantennas enhancement factor and observed an average of 63-fold fluorescence brightness enhancement with a maximum of 93-fold for dye molecules in nanogaps between 20 nm and 50 nm. The experimentally determined fluorescence enhancement of the nanoantennas was confirmed by numerical simulations of the local density of optical states (LDOS). Furthermore, we show that beyond design optimisation of dielectric nanoantennas, increased performances can be achieved via tailoring of nanoantenna fabrication.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Direct Bottom-Up In Situ Growth: A Paradigm Shift for Studies in Wet-Chemical Synthesis of Gold Nanoparticles},

author = {G A Vinnacombe-Willson and Y Conti and A Stefancu and P S Weiss and E Cort\'{e}s and L Scarabelli},

url = {https://doi.org/10.1021/acs.chemrev.2c00914},

doi = {10.1021/acs.chemrev.2c00914},

issn = {0009-2665},

journal = {Chemical Reviews},

volume = {123},

number = {13},

pages = {8488-8529},

abstract = {Plasmonic gold nanoparticles have been used increasingly in solid-state systems because of their applicability in fabricating novel sensors, heterogeneous catalysts, metamaterials, and thermoplasmonic substrates. While bottom-up colloidal syntheses take advantage of the chemical environment to control size, shape, composition, surface chemistry, and crystallography of the nanostructures precisely, it can be challenging to assemble nanoparticles rationally from suspension onto solid supports or within devices. In this Review, we discuss a powerful recent synthetic methodology, bottom-up in situ substrate growth, which circumvents time-consuming batch presynthesis, ligand exchange, and self-assembly steps by applying wet-chemical synthesis to form morphologically controlled nanostructures on supporting materials. First, we briefly introduce the properties of plasmonic nanostructures. Then we comprehensively summarize recent work that adds to the synthetic understanding of in situ geometrical and spatial control (patterning). Next, we briefly discuss applications of plasmonic hybrid materials prepared by in situ growth. Overall, despite the vast potential advantages of in situ growth, the mechanistic understanding of these methodologies remains far from established, providing opportunities and challenges for future research.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}