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Plasmonic Effects of Dual-Metal Nanoparticle Layers for High-Performance Quantum Dot Solar Cells
摘要： To improve quantum dot solar cell performance, it is crucial to make efficient use of the available incident sunlight to ensure that the absorption is maximized. The ability of metal nanoparticles to concentrate incident sunlight via plasmon resonance can enhance the overall absorption of photovoltaic cells due to the strong confinement that results from near-field coupling or far-field scattering plasmonic effects. Therefore, to simultaneously and synergistically utilize both plasmonic effects, the placement of different plasmonic nanostructures at the appropriate locations in the device structure is also critical. Here, we introduce two different plasmonic nanoparticles, Au and Ag, to a colloidal PbS quantum dot heterojunction at the top and bottom interface of the electrodes for further improvement of the absorption in the visible and near-infrared spectral regions. The Ag nanoparticles exhibit strong scattering whereas the Au nanoparticles exhibit an intense optical effect in the wavelength region where the absorption of light of the PbS quantum dot is strongest. It is found that these dual-plasmon layers provide significantly improved short-circuit current and power conversion efficiency without any form of trade-off in terms of the fill factor and open-circuit voltage, which may result from the indirect contact between the plasmonic nanoparticles and colloidal quantum dot films.
关键词： Quantum dot solar cell,Plasmonic effect,Near-field oscillation,Colloidal quantum dot,Light scattering
更新于2025-09-16 10:30:52
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Rapid Room-Temperature Synthesis of Mesoporous TiO2 Sub-Microspheres and Their Enhanced Light Harvesting in Dye-Sensitized Solar Cells
摘要： Submicron sized mesoporous spheres of TiO2 have been a potential alternative to overcome the light scattering limitations of TiO2 nanoparticles in dye‐sensitized solar cells (DSSCs). Currently available methods for the growth of mesoporous TiO2 sub‐microspheres involve long and relatively high temperature multi‐stage protocols. In this work, TiO2 mesoporous sub‐microspheres composed of ~5 nm anatase nanocrystallites were successfully synthesized using a rapid one‐pot room‐temperature CTAB‐based solvothermal synthesis. X‐Ray Diffraction (XRD) showed that the grown structures have pure anatase phase. Transmission electron microscopy (TEM) revealed that by reducing the surfactant/precursor concentration ratio, the morphology could be tuned from monodispersed nanoparticles into sub‐micron sized mesoporous beads with controllable sizes (50–200 nm) and with good monodispersity as well. The growth mechanism is explained in terms of the competition between homogeneous nucleation/growth events versus surface energy induced agglomeration in a non‐micelle CTAB‐based soft templating environment. Further, dye‐sensitized solar cells (DSSCs) were fabricated using the synthesized samples and characterized for their current‐voltage characteristics. Interestingly, the DSSC prepared with 200 nm TiO2 sub‐microspheres, with reduced surface area, has shown close efficiency (5.65%) to that of DSSC based on monodispersed 20 nm nanoparticles (5.79%). The results show that light scattering caused by the agglomerated sub‐micron spheres could compensate for the larger surface areas provided by monodispersed nanoparticles.
关键词： CTAB,light scattering,surfactant,titanium dioxide,dye‐sensitized solar cells,anatase
更新于2025-09-16 10:30:52
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Light Scattering Materials as Photoanodes
摘要： Dye-sensitized solar cells (DSSCs) are existing to be a promising alternative to conventional silicon solar cells owing to its ease of fabrication, low cost, along with the additional features like flexible devices and building integrated photovoltaic system [1]. In general, DSSC architecture comprised of semiconducting photoanode, counter electrode (catalyst), and an electrolyte [2, 3]. In DSSC, the quantity of light caught by the dye-sensitized photoanode has a strong influence on the overall performance because the electrons are generated directly from the excited dye molecules by the irradiated sunlight. One of the primary key tasks is to boost the performance of the device by enriching the photon absorption in DSSCs such as the introduction of a tandem structure and the introduction of a light-scattering effect. Among these developments, the light-scattering effect had more attention than others because of an easy method for enhancing light absorption [4–7]. The simple theory of light scattering effect was introduced by Usami [8] in 1997, stating that a new photoelectrode structure consisting of top layer made up of a large sized particle film on the below layer made up of a small sized particle film; the light scattered by the top layer triggered an increase in the light absorption. In initial days, several studies had been focused on the analysis of the light-scattering effect in the DSSCs by using various simulation methods based on the Monte Carlo model, Mie theory, and the many-flux model. Subsequently, the light-scattering effect had been widely used as an important technique to develop the performance of DSSCs [9]. So, the introduction of light scattering and light scattering materials are explained in the following sections.
关键词： Dye-sensitized solar cells,Rayleigh scattering,TiO2,Mie theory,nanoparticles,light scattering,DSSCs,photoanodes
更新于2025-09-12 10:27:22
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Broadband Plasmonic Enhancement of High-Efficiency Dye-Sensitized Solar Cells by Incorporating Au@Ag@SiO <sub/>2</sub> Core–Shell Nanocuboids
摘要： The introduction of plasmonic additives is a promising approach to boost the efficiency of dye-sensitized solar cell (DSSC) since it may improve the light harvesting of a solar cell. Herein, we design broadband and strong plasmonic absorption Au@Ag@SiO2 nanocuboids (GSS NCs) as nanophotonic inclusions to achieve plasmon-enhanced DSSCs. These multiple resonances absorption arising from GSS NCs can be readily adjusted by altering their structures to complementarily match the absorption spectrum of the dyes, especially in weak absorption zones. By subtly regulating the position of nanophotonic inclusions in the photoanodes, not only the plasmonic near-field enhancement but also far-field light-scattering could be adequately developed to promote the light harvest and thus the efficiency of DSSCs. The resulting solar cells yield an average efficiency of 10.34%, with a champion value of 10.58%. The electromagnetic simulations are consistent with the experimental observations, further corroborating the synergistic effect of plasmonics improvement in these DSSCs.
关键词： near-field effect,light-scattering,light management,plasmon resonance,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Hierarchical flower-like TiO2 microspheres with improved dye-sensitized solar cell performance
摘要： Hierarchical flower-like TiO2 microspheres (FMS) and TiO2 nanorice (NR) were obtained, respectively, by controlling the dosage of Ti precursor via a simple hydrothermal process. Flower-like TiO2 microspheres consist of nanopetals grown from the center radially, the nanopetals are about several nm in average thickness, and each nanopetal has a thinned tip with an average size of 15 nm. The unique hierarchical TiO2 microspheres with large surface area (118.6 m2 g?1) suggested its potential application in dye-sensitized solar cells (DSSCs). The power conversion efficiency of FMS-based DSSCs (9.58%) is much higher than that of NR-based DSSCs (7.13%), which could be ascribed to its excellent light-scattering and dye absorption ability, shorter electron transport pathway and longer electron recombination time derived from the thin thickness and large specific surface area of nanopetals.
关键词： Dye absorption,Hierarchical flower-like TiO2 microspheres,Hydrothermal process,Light-scattering,Dye-sensitized solar cells
更新于2025-09-12 10:27:22
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An Automated Setup for Measuring the Light-Scattering Characteristics of Samples with Rough Surfaces at Laser Wavelengths in the Range of 0.35–1.1 μm
摘要： The description and the operating algorithm of an automated scanning device, which is constructed according to the scheme of a two-coordinate goniophotometer and is intended for measuring the bidirectional reflection function (BDRF) of samples with different degrees of surface roughness at laser wavelengths of 0.53, 0.63, and 1.06 μm, are described. The relative measurement error of the BDRF is 6–9%. Special software and the design features allow one to vary the time and scanning step of the device, while the presence of two measurement channels makes it possible to use radiation sources with a nonstabilized output power. The device has the ability to displace the operating spectral range to the region of the middle and far IR range.
关键词： rough surfaces,BDRF,automated setup,bidirectional reflection function,laser wavelengths,light-scattering characteristics
更新于2025-09-12 10:27:22
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Performance characteristics of the low-cost plantower PMS optical sensor
摘要： Low-cost sensors have become very popular in recent years for monitoring air pollutants. Commonly, they are calibrated by correlating their signals with reference instrument measurements and using a machine learning model to account for the influence of air properties. As particle properties vary over location, such calibration models are only relevant to measurements made at the calibration location during a limited time period. For a more general operation of these sensors it is critical that their measurement performance is established using the calibration approaches commonly for research grade instruments. Without loss the generality, here we conducted an experimental study with size-classified, composition and concentration varied particles to determine the response function of a popular low-cost sensor, Plantower PMS5003. The sensor response in all the size channels is analyzed using Tikhonov regularization and quadratic programing method with the constraints of nonnegative and monotonic response with particle size. We show that the shape of the response function is closely related to the light scattering response, consistent with what might be expected for an optical sensor. The response function shows that signals in all size channels have a complex dependence on particle material and size distribution. Accurate determination of particle mass and number distributions from the sensor signals in different channels is, thus, not straightforward. The response function calculation is validated by comparing sensor measured and predicted signals using polydispersed particles. The obtained response functions provide critical insight into the operation of a popular low-cost sensor and guidance on interpretation of its results.
关键词： light scattering response,Plantower PMS5003,quadratic programing,Tikhonov regularization,low-cost sensors,air pollutants
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Plasmonic Random Laser with the Embedding of Silver Nanostructure Materials
摘要： In contrast to conventional lasers, random lasers (RLs), without cavity mirrors, were generated based on recurrent light scattering within nano-materials and possessed peculiar properties for practical applications. To date, researchers are not only interested in the novel nano-materials for the generation of RL but also curious in the manipulated property of RL through temperature and electric filed [1]. In addition, plasmonic random laser (PRL)[2] based on the localized surface plasmon resonance (LSPR) of metallic nanoparticles has attracted great interest. In this work, the dye-covered PVA (DC-PVA) film with the embedding of silver nano-particles (AgNPs) was produced to investigate the enhancement of emission spike intensity from PRL and the underlying mechanism by varying the size and shape of AgNPs. Here, the AgNPs were synthesized by a soft solution-phase approach inside the DI water [3]. Depending on the size and shape of AgNPs in colloidal solution, the absorbance spectrum in Fig. 1(a) reveals different peak absorption wavelength (λp) at 404 nm and 610 nm, respectively, and shows deep yellow and navy color (Fig. 1(a)). The PVA film with embedding of AgNPs (PVA/AgNPs) was produced by dropping the mixed solution, comprising PVA powder and AgNPs, onto a glass substrate. After drying, the laser dye (Pyrromethene 597, Exciton inc.) was coated on the top of PVA film (Inset of Fig. 1: the structure of sample). In this work, the coherent back scattering measurement (CBS) measurement [4] was performed to obtain the transport mean free path (lp) of pure DC-PVA film (green squares: Sample-I) and DC-PVA/AgNP film [red triangles: Sample-II (λp at 405 nm), blue circle: Sample-III (λp around 610 nm)]. The solid lines represent the theoretical fitting curves to obtain the lp of three samples around 10.3, 8.7 and 3.6 μm. The value of lp decreases obviously after AgNPs was embedding in the PVA film to illustrate the enhancement of light scattering. In order to generate RL, we excited all the produced samples by a frequency doubling Q-switched Nd:YAG laser with a central wavelength of 532 nm. The 10 Hz pump pulses were focused onto the sample with a long line stripe by a cylindrical lens with focal length f = 7cm. The side emission of the sample was collected by the fiber tip and measured by the spectrometer (resolution about 0.3 nm, Ocean Optics Inc.). Inset of Fig. 1(b) shows the emission spectra of DC-PVA film without (Sample-I, green solid curve) and with (Sample-II: red solid curve and Sample-III: blue solid curve) AgNPs. Even at relatively high pulse energy, the Sample-I (without AgNPs) only reveals broad spontaneous emission spectrum with the maximum intensity at λ = 578 nm. For the sample-II and sample-III (DC-PVA/AgNP film), the discrete emission spikes at around about λ=576 and 583 nm on the top of broad spontaneous emission can be revealed which is the characteristic of RL. In order to qualitatively distinguish the operation state of RL, the α-stable distribution [5] proposed by Uppu et al. was used to analysis the intensity fluctuation (red) of the sample by sampling 1000 spectrum slots. The intensity distribution (red histogram) can be theoretical fitting by the equation (blue solid curves in Figs. 1(c) and 1(d)) to obtain the α=1.99 and 1.58, respectively, which reveals the Gaussian and Levy distribution.
关键词： random lasers,light scattering,localized surface plasmon resonance,plasmonic random laser,silver nano-particles
更新于2025-09-12 10:27:22
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Online Monitoring of Cell Growth on PDMS-PDMS Reversible Microfluidic Bioreactor Integrated to Optical Fiber Sensor
摘要： A microfluidic bioreactor was fabricated by curing PDMS over 3D-printed molds, and it contains microchannels and perfusion chambers instrumented with optical fibers for the online analysis of the cellular growth. The channels were designed for allowing both the complete mixture of reagents and the possibility of generation of concentration gradients, and the perfusion chambers are isolated from them by polycarbonate membranes, providing a chemical environment with a constant concentration of nutrients for the cells. The optical fibers are laterally inserted in the chambers, and the monitoring of cells concentration is based on the quasi-elastic light scattering: as the total number of cells grows, there is an increase on the dispersion of the reflected intensity data, and the autocorrelation of the values allows the inference of the concentration. The sensor signals obtained during the fermentation of S. cerevisiae were equivalent to the cell counting on the Neubauer chamber using an optical microscope, leading to a value of the maximum specific growth rate μm of 0.50 h-1. This optical monitoring system has proven to be easily manufacturable and capable of performing fast screening and online monitoring of the microbial kinetics.
关键词： microbial kinetics,online monitoring,optical fiber sensor,quasi-elastic light scattering,Microfluidic bioreactor
更新于2025-09-12 10:27:22
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Effect of metal ion solubility on the oxidative assembly of metal sulfide quantum dots
摘要： The versatility of the oxidative assembly method for the creation of 2D and 3D quantum dot (QD) architectures represents both an opportunity and a challenge as a method enabling controlled placement of chemically distinct QDs in multicomponent systems. The opportunity lies in the ability to independently tune the kinetics of the different components so that they are similar (leading to well-mixed systems) or different (enabling gradient or phase-segregated composites) using a wide range of variables; the challenge lies in understanding those variables and how their interplay affects the overall kinetics. Here, we show that the identity of the cation in the sulfide matrix (M = Cd2+ vs Zn2+) plays a large role in the kinetics of assembly of mass spectrometry QDs, attributed to differences in solubility. Time resolved dynamic light scattering is used to monitor the hydrodynamic radius, Rh. ZnS shows an exponential growth associated with reaction-limited cluster aggregation (RLCA), whereas CdS demonstrates a significant induction period (10–75 min) followed by a growth step that cannot be distinguished between RLCA and diffusion limited cluster aggregation. These data correlate with relative solubilities of the nanoparticles, as probed by free-cation concentration. Data also confirm prior studies showing that cubic-closest-packed (ccp) lattices are kinetically slow relative to hexagonally closest-packed (hcp); using the slope of the ln Rh vs time plot for the rate constant, the values of 0.510 s?1 and 3.92 s?1 are obtained for ccp ZnS and hcp ZnS, respectively. Thus, both the structure and the solubility are effective levers for adjusting the relative reactivity of QDs toward oxidative assembly.
关键词： kinetics,solubility,quantum dots,dynamic light scattering,oxidative assembly
更新于2025-09-12 10:27:22