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- 2019
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- PIN diode
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- Ufa State Aviation Technical University
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- Fraunhofer Institute for Applied Optics and Precision Engineering IOF
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Transparent Sn-doped In2O3 electrodes with a nanoporous surface for enhancing the performance of perovskite solar cells
摘要： We report on a simple and efficient process to enhance the performance of perovskite solar cells by using ITO electrodes with a nanoporous surface formed by wet-etching of self-agglomerated Ag nanoparticles. Effective removal of the Ag nanoparticles embedded in the surface of the ITO electrodes result in a nanoporous structure without changing the ITO's sheet resistance (10.17 Ω/square) and optical transmittance (89.08%) at a 550 nm wavelength. Examinations with a scanning electron microscope, a transmission electron microscope, and two-dimensional porous mapping show that the nanoporous ITO surface has an increased contact area with the electron transport layer, which enhanced the carrier extraction efficiency of the perovskite solar cells. Compare to perovskite solar cells fabricated on typical ITO with a flat surface morphology, the perovskite solar cells fabricated on the nanoporous-surface ITO show a higher fill factor of 81.1% and a power conversion efficiency of 20.1%. These results indicate that modified ITO surfaces with nano-scale porosity provide a simple and efficient method to improve the power conversion efficiency of perovskite solar cells without a complicated process.
关键词： Contact area,Nanoporous surface,Sn-doped In2O3,Ag agglomeration,Perovskite solar cells
更新于2025-11-21 10:59:37
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Cu nanoclusters in ion exchanged soda-lime glass: Study of SPR and nonlinear optical behavior for photonics
摘要： Nanomaterials with large optical nonlinearities have received considerable attention in the field of modern science and nanotechnology. In this paper, we have studied nonlinear optical and surface plasmon resonance properties and behavior of Cu nanoclusters formed in ion exchanged soda-lime glass. The soda-lime glasses were successfully doped with Cu nanoclusters in the ion-exchange process. The size of the clusters estimated from the optical absorption spectroscopy results closely matched with those obtained from the transmission electron microscopy data. The results revealed that spherical shaped Cu nanoclusters were homogeneously distributed in the glass matrix and the size of the Cu nanoclusters varied from 4 to 10 nm. The structure and chemical state were further analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The nonlinear optical behavior of the materials was analyzed using femtosecond Z-scan technique. The nonlinear refraction index (n2), nonlinear absorption coefficient (β) and the third-order nonlinear optical susceptibility (χ(3)) were estimated to be -1.72 × 10?17 m2/W, 9.96 × 10?11 m/W, and 0.56 × 10?11 esu, respectively, which shows possible application in the field of photonics.
关键词： Surface plasmon resonance,Z-scan technique,Metal forming and shaping,Structural,Nanoparticles
更新于2025-11-20 15:33:11
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Plasmonic Metasurfaces with Tunable Gap and Collective SPR Modes
摘要： Optical properties of a plasmonic metasurface made of a monolayer of gold nanoparticles in close proximity to an aluminum thin film were studied numerically and experimentally. Extinction spectra of the plasmonic metasurface were studied as functions of the thickness of a dielectric spacer between the monolayer of gold nanoparticles and the aluminum film in the visible wavelength range. The goal was to understand the excitation of a collective surface plasmon resonance (SPR) mode and a gap plasmon mode as well as their dependence on the spacer thickness, nanoparticles spacing and their size. By using finite-difference-time-domain (FDTD) calculations we find that the SPR extinction peak first red-shifts and then splits into two peaks. The first extinction peak is associated with the collective SPR mode of the monolayer and it shifts to shorter wavelengths as the spacer layer decreases. As the spacer layer decreases from 35 nm to 7.5 nm, the second peak gradually appears in the extinction spectra of the metasurface. We assign the second peak to the gap mode. The gap mode first appears at around 620 nm or greater and it shifts to larger wavelength for larger nanoparticle spacing and size. The FDTD simulations are confirmed by an experimental examination of the dispersion curves of a similar multilayer system. The computational results match the experimental results and confirm the excitation of the two modes.
关键词： gap plasmon mode,surface plasmon resonance,Plasmonic metasurfaces,aluminum thin film,FDTD,gold nanoparticles
更新于2025-11-19 16:56:42
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Tailoring optical cross sections of gold nanorods at a target plasmonic resonance wavelength using bromosalicylic acid
摘要： In many applications, the optical cross sections of gold nanorods (AuNRs) are required to be tailored at a fixed target longitudinal surface plasmon resonance (LSPR) wavelength depending on the excitation source and the photodetector. In this work, we demonstrate the fine tailoring of optical cross sections of AuNRs at a fixed target resonance wavelength, on the basis of AuNR overgrowth using a binary surfactant mixture consisting of 5-bromosalicylic acid (BSA) and cetyltrimethylammonium bromide (CTAB). A systematic study was performed on the sum effects of the BSA concentration and the volume of the growth solution, which gives a formula for quantitative instructions. Based on the formula, we gave examples for the successful synthesis of AuNRs with different optical cross sections at target LSPR wavelengths. From simulation, a nonlinear relationship was further derived to understand the relationship between the aspect ratio and the width of the AuNRs at a target LSPR wavelength for the dimension design of AuNRs. The ratio of optical against physical cross sections was calculated and plotted as a function of the width. The results clearly indicate that AuNRs with a width of 30 nm possess the highest efficiency in terms of optical per physical cross section. Our study provides reliable methods for the synthesis, as well as guidelines for the dimension design of AuNRs, for use in a variety of applications.
关键词： 5-bromosalicylic acid,gold nanorods,optical cross sections,cetyltrimethylammonium bromide,surface plasmon resonance
更新于2025-11-19 16:56:42
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Triplet-State Photochemistry of Dissolved Organic Matter: Triplet-State Energy Distribution and Surface Electric Charge Conditions
摘要： Excited triplet states of chromophoric dissolved organic matter (3CDOM*) are highly reactive species in sunlit surface waters and play a critical role in reactive oxygen species (ROS) formation and pollutant attenuation. In the present study, a series of chemical probes, including sorbic acid, sorbic alcohol, sorbic amine, trimethylphenol, and furfuryl alcohol, were employed to quantitatively determine 3CDOM* and 1O2 in various organic matters. Using a high concentration of sorbic alcohol as high-energy triplet states quencher, 3CDOM* can be first distinguished as high-energy triplet states (>250 kJ mol?1) and low-energy triplet states (<250 kJ mol?1). The terrestrial-origin natural organic matter (NOM) was found to mainly consist of low-energy triplet states, while high-energy triplet states were predominant in autochthonous-origin NOM and effluent/wastewater organic matter (EfOM/WWOM). The 1O2 quantum yields and electron transfer quantum yield coefficients (f TMP) generated from low-energy triplet states remained constant in all tested organic matters. External phenolic compound showed quenching effects on triplet-state formation and tended to have a higher quenching efficiency for aromatic ketone triplet states, which are the main high-energy triplet states. In comparison with terrestrial-origin NOM, autochthonous-origin NOM and EfOM/WWOM presented lower reaction rate constants for sorbic amines and higher reaction rate constants for sorbic acid, and these differences are likely due to dissimilar surface electric charge conditions. Understanding the triplet-state photochemistry of CDOM is essential for providing useful insights into their photochemical effects in aquatic systems.
关键词： surface charge,triplet-state photochemistry,energy distribution,dissolved organic matter,reactive oxygen species,chemical probes
更新于2025-11-19 16:56:35
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Atmospheric Pressure Plasma Synthesized Gold Nanoparticle/Carbon Nanotube Hybrids for Photo-thermal Conversion
摘要： In this work, a room temperature atmospheric pressure direct-current plasma has been deployed for the one-step synthesis of gold nanoparticle/carboxyl group functionalized carbon nanotube (AuNP/CNT-COOH) nanohybrids in aqueous solution for the first time. Uniformly distributed AuNPs are formed on the surface of CNT-COOH, without the use of reducing agents or surfactants. The size of the AuNP can be tuned by changing the gold salt precursor concertation. UV-Vis, ζ-potential and X-ray photoelectron spectroscopy suggest that carboxyl surface functional groups on CNTs served as nucleation and growth sites for AuNPs and the multiple potential reaction pathways induced by the plasma-chemistry have been elucidated in detail. The nanohybrids exhibit significantly enhanced Raman scattering and photothermal conversion efficiency, properties that are essential for potential multi-modal cancer treatment applications.
关键词： Surface Enhanced Raman Scattering,Gold Nanoparticles,Photothermal Conversion,Carbon Nanotubes,Plasma Synthesis
更新于2025-11-19 16:56:35
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LSPR Biosensing Approach for the Detection of Microtubule Nucleation
摘要： Microtubules are dynamic protein ?laments that are involved in a number of cellular processes. Here, we report the development of a novel localized surface plasmon resonance (LSPR) biosensing approach for investigating one aspect of microtubule dynamics that is not well understood, namely, nucleation. Using a modi?ed Mie theory with radially variable refractive index, we construct a theoretical model to describe the optical response of gold nanoparticles when microtubules form around them. The model predicts that the extinction maximum wavelength is sensitive to a change in the local refractive index induced by microtubule nucleation within a few tens of nanometers from the nanoparticle surface, but insensitive to a change in the refractive index outside this region caused by microtubule elongation. As a proof of concept to demonstrate that LSPR can be used for detecting microtubule nucleation experimentally, we induce spontaneous microtubule formation around gold nanoparticles by immobilizing tubulin subunits on the nanoparticles. We ?nd that, consistent with the theoretical model, there is a redshift in the extinction maximum wavelength upon the formation of short microtubules around the nanoparticles, but no signi?cant change in maximum wavelength when the microtubules are elongated. We also perform kinetic experiments and demonstrate that the maximum wavelength is sensitive to the microtubule nuclei assembly even when microtubules are too small to be detected from an optical density measurement.
关键词： localized surface plasmon resonance,optical biosensors,gold nanoparticles,microtubule nucleation
更新于2025-11-19 16:56:35
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Reversible/Irreversible Photobleaching of Fluorescent Surface Defects of SiC Quantum Dots: Mechanism and Sensing of Solar UV Irradiation
摘要： Knowledge about photobleaching properties of the fluorescent surface defects of the semiconductor quantum dots (QDs) is crucial for their applications. Here, the photobleaching properties of the fluorescent surface defects of the colloidal 3C-SiC QDs are reported. The combined experimental and theoretical study reveals that the observed violet fluorescence at around 392 nm stems from the carboxylic acid group-related surface defects. When the SiC QDs are exposed to the UV irradiation, the 392 nm fluorescent surface defects show both reversible and irreversible photobleaching, whereas the 438 nm fluorescent surface defects show only irreversible photobleaching. The photochemical mechanisms dominating these phenomena are explored. The photobleaching property of the SiC QDs is utilized to detect the solar UV irradiation with high accuracy. The photobleaching of the SiC QDs is highly sensitive to the hydrogen or metal ion concentration in the colloid solution. These findings deepen the understanding of the properties of the fluorescent surface defects of the SiC QDs and pave the way for their applications in sensing.
关键词： photobleaching,silicon carbide quantum dots,surface defects,fluorescence mechanism
更新于2025-11-19 16:46:39
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Multifunctional N,S co-doped carbon dots for sensitive probing of temperature, ferric ion, and methotrexate
摘要： In this paper, we have presented a facile method to fabricate nitrogen and sulfur co-doped carbon dots (N,S-CDs) for blood methotrexate (MTX) sensing applications. The N,S-CDs with quantum yield up to 75% were obtained by one-step hydrothermal carbonization, using reduced glutathione and citric acid as the precursors. With this approach, the formation and the surface passivation of N,S-CDs were carried out simultaneously, resulting in intrinsic fluorescence emission. Owing to their pronounced temperature dependence of the fluorescence emission spectra, resultant N,S-CDs can work as versatile nanothermometry devices by taking advantage of the temperature sensitivity of their emission intensity. In addition, the obtained N,S-CDs facilitated high selectivity detection of Fe3+ ions with a detection limit as low as 0.31 μM and a wide linear range from 3.33 to 99.90 μM. More importantly, the added MTX selectively led to the fluorescence quenching of the N,S-CDs. Such fluorescence responses were used for well quantifying MTX in the range of 2.93 to 117.40 μM, and the detection limit was down to 0.95 μM. Due to Binert^ surface, the N,S-CDs well resisted the interferences from various biomolecules and exhibited excellent selectivity. The proposed sensing system was successfully used for the assay of MTX in human plasma. Due to simplicity, sensitivity, selectivity, and low cost, it exhibits great promise as a practical platform for MTX sensing in biological samples.
关键词： Hydrothermal carbonization,Doped carbon dots,Excitation-independent emission,Multifunctional probe,Methotrexate,Surface passivation
更新于2025-11-19 16:46:39
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Latent fingermark detection using functionalised silicon oxide nanoparticles: Method optimisation and evaluation
摘要： The application of nanoparticles for latent fingermark detection has been reported in the literature over the past two decades. One of the nanoparticles that shows promise to become a routine technique is functionalised silicon oxide nanoparticles (SiO2 NPs). In a recent optimisation of the technique, the use of carboxyl-functionalised SiO2 NPs doped with luminescent ruthenium complex was proposed as a breakthrough for latent fingermark detection. In this study, the aforementioned functionalised SiO2 NPs were extensively evaluated. Modification and optimisation of the original detection parameters were performed to enhance detection quality and improve applicability. Various detection parameters were evaluated and assessed. A lower concentration of the functionalised nanoparticles used in the colloidal dispersion was determined to offer improved detection effectiveness. A combination of increased bath temperature and reduced immersion time was found to produce good overall results. A set of modified detection parameters was suggested for the use of the functionalised SiO2 NPs to detect latent fingermarks. Performance of the modified detection parameters was compared against that of the published detection method. Comparison experiments were carried out on fingermark specimens deposited on aluminium foil, transparent polypropylene plastic and green polyethylene plastic. Three donors (weak, average and strong) and two age intervals (ten days and three months) were considered in the comparison study. Evaluation of the results suggested that the overall performance of the modified method for latent fingermark detection was superior to that obtained using the previously published detection parameters.
关键词： Bath temperature,Detection effectiveness,Method modification,Colloidal,Surface functionalisation,Luminescence technique
更新于2025-11-19 16:46:39