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Ultrafast Exciton Dissociation at the 2D-WS <sub/>2</sub> Monolayer/Perovskite Interface
摘要： In order for an excitonic photovoltaic (PV) device to perform efficiently, photogenerated excitons in the charge donor need to be dissociated through charge transfer (CT) to the acceptor rapidly after their photogeneration, and remain separated for a longer time to allow the collection of charges. To improve the efficiency of these steps, several combination of materials have been examined. Due to their excellent optical properties, two-dimensional transition metal dichalcogenides (2D-TMDs) have recently been explored. Another promising class of materials to platform efficient PVs is organic-inorganic perovskites. Here, we report on the ultrafast exciton dissociation through electron transfer from a 2D tungsten disulfide (WS2) monolayer to a thin layer of methylammonium lead iodide (CH3NH3PbI3) perovskites. Photoluminescence (PL) measurements showed that when the 2D-WS2 monolayer was covered with perovskites, its emission completely quenched, suggesting that the CT process is highly efficient. Despite that pump-probe spectroscopy measurements were carried out with a ~ 45 fs temporal resolution, the CT dynamics were not captured. A comparison of the ultrafast dynamics of the two band-edge excitons of the charge donor (2D-WS2) suggested that electron transfer is the dominant pathway of CT. Furthermore, these pump-probe measurements indicated that a small fraction of transferred electrons remained in the perovskites up to almost 2 ns. These findings may open a new horizon for understanding the dissociation of photogenerated excitons in 2D-TMD through hybridization with other class of nanomaterials.
关键词： Ultrafast Exciton Dissociation,Perovskite Interface,Hybrid Materials,Magnetic,Plasmonics,2D-WS2 Monolayer,Optical
更新于2025-09-23 15:21:01
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Highly Emissive Hierarchical Uniform Dialkylfluorene-Based Dimer Microcrystal for Ultraviolet Organic Laser
摘要： Hierarchically uniform condensed structure of light-emitting conjugated molecules is an effective platform to obtain excellent electronic landscape with little physical defect and further improve photophysical property. Herein, highly emissive dialkylfluorene-based dimer crystal structure is constructed with crystalline-enhanced emission for ultraviolet organic microlasers. Instable planar conformation of fluorene dimer can be stabilized in a rigid crystalline framework, which is a fundamental factor to fabricate hierarchically uniform structure (including planar conformational molecules and periodical molecular packing in crystalline structure). Therefore, high photoluminescence quantum efficiency (PLQE) of 50% and 75% are obtained for neat spin-coated film and single crystals, attributing to the little physical defect in this hierarchical oriented structure. This robust crystalline-enhanced emission enables its microcrystals to construct ultraviolet organic lasers (395 nm) with a low threshold of 7.65×10-3 nJ cm-2 pulse-1, which is 4 times lower than that of controlled trimer one (TDMeF). These observations reasonably confirm that hierarchically ordered architecture of conjugated materials show great promise in optoelectronic applications.
关键词： Plasmonics,Dimer Microcrystal,Dialkylfluorene,Hybrid Materials,Magnetic,Optical,Ultraviolet Organic Laser
更新于2025-09-23 15:19:57
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Optoplasmonics: basic principles and applications
摘要： Plasmonic and photonic elements often have complementary optical properties, motivating the development of ‘optoplasmonic’ hybrid systems in which the photonic and plasmonic elements can synergistically interact. The overall goal in the design of optoplasmonic structures is to overcome the limitations of the individual building blocks or to generate entirely new properties that reach beyond what is possible with conventional photonic or plasmonic structures. After providing a brief introduction into the relevant optical properties of plasmonic and photonic building blocks, this manuscript reviews optoplasmonic architectures that contain plasmonic nanoantennas embedded in a de?ned photonic environment generated by discrete dielectric nanoparticles (NPs), microcavities, waveguides, or photonic crystals, as well as all-metal NP or metal/dielectric NP hybrid arrays in which diffracted modes interact with the plasmons of metal NPs. The fundamental working principles of these optoplasmonic systems are analyzed and selected applications and fabrication strategies are discussed.
关键词： metamaterials,metasurface,sensing,hybrid materials,high refractive index dielectrics,plasmonics,nanophotonics
更新于2025-09-23 15:19:57
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Exploring the Relationship between Intermolecular Interactions and Solid-state Photophysical Properties of Organic Co-crystals
摘要： Five new binary co-crystals have been prepared through molecular self-assembly of π-electron-rich molecules like Phenanthrene (PHEN), Benzo[c]cinnoline (BCC) and Phenazine (PHNZ) in the presence of π-electron-deficient molecules like Tetrafluoro-1,4-benzoquinone (TFQ), Tetrachloro-1,4-benzoquinone (TCQ) and 1,2,4,5-Tetracyanobenzene (TCNB), taken in an equimolar ratio. Crystal structure analysis revealed that in three binary co-crystals the constituent molecules were alternately sandwiched in a cofacial arrangement through π···π interactions, while in the remaining two binary co-crystals the constituent molecules were aligned in a unique edge-to-face manner through lp···π interactions. Co-crystals with π-stacking arrangement were fluorescent, whereas almost complete quenching of luminescence was observed in those having edge-to-face alignment of molecules. The photophysical observations of these co-crystals have been demonstrated via energetic quantification of intermolecular interaction topology, which provides a molecular level understanding of factors controlling their solid-state absorption and luminescence behavior.
关键词： Magnetic,Organic Co-crystals,Plasmonics,Solid-state Photophysical Properties,Intermolecular Interactions,Optical,Hybrid Materials
更新于2025-09-23 15:19:57
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Extraordinarily Large Third-Order Optical Nonlinearity in Au Nanorods under Nanowatt Laser Excitation
摘要： Size and operating energy are two key parameters that constrain the integration capability of a nonlinear optical device. Here, we report a 60-nm thin film made of randomly distributed gold nanorods that demonstrates extraordinarily large third-order nonlinear optical absorption under an excitation power as low as 100 nanowatts. Where the effective nonlinear optical absorption (NLA) coefficient is calculated to be 8x109 cm/GW with the corresponding optical susceptibility (Imχ(3)) of 7.6x10-2 esu, which is 3-4 orders larger than that of other metallic nanostructures. The sign of the NLA could be controlled by changing the excitation wavelength or varying the pump power. The optical Kerr effect measurement also shows that the intrinsic χ(3) of our sample is quite large compared to other nanostructures. Our work eliminates the requirements of strong operation power and large physical size of nonlinear optical materials and offers new opportunities for plasmonic nanostructures in applications of on-chip nonlinear optical devices.
关键词： Nanowatt Laser Excitation,and Hybrid Materials,Optical,Plasmonics,Magnetic,Au Nanorods,Third-Order Optical Nonlinearity
更新于2025-09-19 17:13:59
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Light-induced Polymer Response Through Thermoplasmonics Transduction in Highly Monodisperse Core-Shell-Brush Nanosystems
摘要： Smart nanosystems that transduce external stimuli to physical changes are an inspiring challenge in current materials chemistry. Hybrid organic-inorganic materials attract great attention due to the combination of building blocks responsive to specific external solicitations. In this work, we present a sequential method for obtaining an integrated core-shell-brush nanosystem that transduces light irradiation into a particle size change through a thermoplasmonic effect. We first synthetize hybrid monodisperse systems made up of functionalized silica colloids covered with controllable thermo-responsive Poly(N-isopropylacrylamide), PNIPAm, brushes, produced through radical photopolymerization. This methodology was successfully transferred to Au@SiO2 nanoparticles, leading to a core-shell-brush architecture, in which the Au core acts as a nano-source of heat; the silica layer, in turn, adapts the metal and polymer interfacial chemistries and can also host a fluorescent dye for bioimaging. Upon green LED irradiation, a light-to-heat conversion process leads to the shrinkage of the external polymer layer, as proven by in situ DLS. Our results demonstrate that modular hybrid nanosystems can be designed and produced with photo-thermo-physical transduction. These remote-controlled nanosystems present prospective applications in smart carriers, responsive bioscaffolds or soft robotics.
关键词： photothermal effect,hybrid materials,in-situ DLS,UV-photo induced polymerization,core-shell-brush colloids,Smart nanosystems
更新于2025-09-19 17:13:59
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Plasmonic Electricity: Fluorophore-Induced Plasmonic Current
摘要： Fluorophore-induced plasmonic current is generated when an excited fluorophore in close proximity to a metal nanoparticle film non-radiatively transfers energy to the metal, resulting in an electrical current across the film. Although a growing literature reports the use of surface plasmons for fluorescence enhancement as well as plasmons for current generation, little has been published hitherto regarding the electrical current generation via the fluorophore excitation of plasmons. Our “plasmon to current” technique utilizes electron transport between closely spaced metal nanoparticles, generating a measureable electrical signal upon excitation of a proximal fluorophore. This induced electrical signal is found to be strongly dependent on the magnitude of the fluorophore extinction coefficient. In other words the electrical signal contains photophysical information pertaining to the fluorophore, potentially leading to the direct detection of fluorescence without the need for traditional detectors such as photomultiplier tubes and charge coupled devices. In addition, we demonstrate the dependence of this current on fluorophore concentration and excitation laser polarization. Fluorophore-induced plasmonic current holds potential as a novel molecular detection platform with simplified instrumentation, compatible with a variety of fluorescent probes.
关键词： Plasmonics,Fluorophore-Induced Plasmonic Current,Hybrid Materials,Magnetic,Optical
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - In situ and ex situ Investigations of Oxygen, Light and Temperature Influence on Halide Perovskites: Absorption and Transport Properties
摘要： In this work multi-cations hybrid perovskite thin film properties were explored by characterization techniques that proved to be very powerful for inorganic thin films. In particular, we report the evolution of the ambipolar diffusion length under different environmental or thermal stresses by Steady State Photocarrier Grating, directly observing the effects of oxygen absorption/desorption onto the material electronic properties. Moreover, the effects of illumination on the absorption properties were investigated via Fourier Transform Photocurrent Spectroscopy, a technique that allows to access to weak absorptions (E<Eg).
关键词： charge carrier lifetime,photovoltaic cells,organic inorganic hybrid materials
更新于2025-09-19 17:13:59
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White-emitting protein-metal nanocluster phosphors for highly performing bio-hybrid light-emitting diodes
摘要： This work presents a simple in-situ synthesis and stabilization of fluorescent gold nanoclusters (AuNCs) with different sizes using engineered protein scaffolds in water. The protein-AuNC hybrids show a dual emission (450 and 700 nm) with a record photoluminescence quantum yield of 20%. These features impelled us to apply them to bio-hybrid light-emitting diodes (Bio-HLEDs) as color down-converting filters or bio-phosphors. Efficient white emission (x/y CIE color coordinates of 0.31/0.29) and stabilities of >800 h were achieved. This represents a two orders of magnitude enhancement compared to the prior art. Besides the outstanding performance, the protein scaffold also infers a unique anisotropic emission character that is considered as a proof-of-concept of high interest for single-point lighting and display.
关键词： bio-phosphors,protein design,Light-emitting diodes,repeat proteins,bio-hybrid materials,metal nanocluster
更新于2025-09-19 17:13:59
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Formation Thermodynamics, Stability, and Decomposition Pathways of CsPbX <sub/>3</sub> (X = Cl, Br, I) Photovoltaic Materials
摘要： Standard enthalpies of formation of CsPbX3 (X = Cl, Br, I) perovskites from halides and from elements at 298 K were measured using solution calorimetry. Intrinsic and extrinsic stabilities of CsPbX3 halides were analyzed and compared with those of CH3NH3PbX3. The main difference between the stabilities of CsPbX3 and CH3NH3PbX3 halides was found to stem from the different chemical nature of cesium and methylammonium cations. Indeed, the enthalpies of formation of CsPbX3 from binary constituent halides, ?fH○hal, are only slightly more negative than those of CH3NH3PbX3. Small values of ?fH○hal imply that the entropic contribution to the Gibbs free energy of formation of CsPbX3 and CH3NH3PbX3 is significant and, hence, of utmost importance for understanding the intrinsic stability of these compounds and their analogs. Regarding the extrinsic stability, the presence of gaseous O2, H2O, and CO2 was shown to be crucial for the stability of the iodide, CsPbI3, for which several decomposition reactions, exergonic at 298 K, were identified. At the same time, chloride, CsPbCl3, and bromide, CsPbBr3, are much less sensitive to these chemical agents. However, liquid water should degrade all the CsPbX3 halides.
关键词： Plasmonics,Stability,Decomposition Pathways,Hybrid Materials,Thermodynamics,Magnetic,Photovoltaic Materials,CsPbX3,Optical
更新于2025-09-16 10:30:52