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The article describes the features of photoluminescence (PL) of silicon and carbon nanocolloids prepared by us using known approaches. In the course of the study, Si and C nanoparticles (NPs) were dispersed in non-polar and polar liquids, respectively, in order to study their photoluminescent properties as a function of temperature. For a number of samples, a bathochromic shift in the position of the PL maximum was observed, as well as a change in the PL intensity depending on the solvent and temperature. The latter opens up prospects for applications of PL thermometry, for example, for mapping the temperature distribution. We calculated the temperature coefficients of changes in the PL intensity as a function of temperature, and in addition, we found that the relatively important temperature sensitivity is associated not only with the internal properties of Si NPs and C NPs, but also, to a large extent, with the mechanisms of the Forster resonant energy transfer in non-polar liquids. The latter is probably realized between particles of different sizes and significantly depends on the change in the viscosity of the liquid with decreasing temperature, which prevents the chaotic movement of NPs and their aggregates in the solution. Presumably, the resonant transfer of Forster energy between Si particles can be the reason that then interactions at short distances between particles of different sizes are possible, in the cases when the NP size distribution is relatively large. Therefore, based on the foregoing, the main directions for improvement should be the development of unified Si NPs and C NPs to clarify the recorded effect and increase the sensitivity in luminescence thermometry using the required type of colloidal solutions and solvent for the respective NPs. The information presented in the article is of interest since it forms the basis for understanding the observed effects during the analysis of experimental data using the available literature sources.

A new mechanism for enhanced intersystem crossing in coupled three-spin systems consisting of a chromophore and an attached radical is proposed. It is shown that if the unpaired electron of the radical experiences spin-orbit coupling and different exchange interactions with the two unpaired electron spins of the chromophore, energy transfer from the chromophore to the radical can occur together with singlet-triplet intersystem crossing in the chromophore. The efficiency of this process increases dramatically when the electronic excitation of the radical is resonant with the S1-T1 energy gap of the chromophore. The types of systems in which this resonance could be achieved are discussed, and it is suggested that the mechanism could result in improved sensitization in near-IR emitting lanthanide dyes.

The transient absorption spectra dynamics for hybrid associates of colloidal CdS quantum dots, passivated by thioglycolic acid (CdS/TGA QDs), and methylene blue cationic dye molecules (MB+) were studied by femtosecond spectroscopy. It was established that one of the main channels of relaxation of the CdS/TGA QDs excitation energy in hybrid associates based on CdS/TGA QDs and MB+ is a fast energy transfer to the reduced forms of MB+ (MBOH•, MB•) that are formed still at the synthesis stage of samples. This channel strongly competes with the resonant energy transfer from the centers of radiative recombination in quantum dots to MB+. Therefore, for hybrid associates based on QDs/TGA and methylene blue, there is no any noticeable signal of the transient absorption corresponding to the triplet state of MB+ dye, which is then known to be actively involved in charge transfer.

The development of detection method for aflatoxin gene cluster in Aspergillus flavus and Aspergillus parasiticusis is an effective approach to prevent the widespread of aflatoxins, which are considered as extremely, toxic substances. Herein, a hairpin DNA-assisted fluorescence probe switch based on Forster resonant energy transfer (FRET) was designed. In this work, the two terminals of hairpin DNA probe were combined with CdTe/CdS quantum dots as donor and gold nanoparticles (AuNPs) as acceptor respectively to fabricate the FRET hairpin probe switch, which were utilized to detect the aflatoxigenic fragment of aflD genes for the first time. In the absence of target DNA, the hairpin probe formed the double stem loops state to trigger the FRET to induce the fluorescence-quenching (turning off). With the addition of target DNA, the specific interaction between target and hairpin probe switch brought about the separation of fluorescent energy donor–acceptor pairs to create an increasing fluorescence response (turning on). Consequently, the fluorescence intensity recovers can be employed to detect aflD genes in homogenous phase through optical responses. This proposed FRET hairpin probe switch performed a great limit of detection of 0.02 nM with a linear range of 0.05–200 nM under optimal conditions. Furthermore, the feasibility of the fabricated strategy was demonstrated in fermented soybean paste with the advantages of simplicity, rapidity, and sensitivity, which indicated that this method exhibited the potential and practicability in foodborne biological samples.

Multiple-receiver resonant inductive coupling wireless power transfer (RIC-WPT) technique is emerging as a promising charging method for multiple household appliances, mobile devices, and wearable devices. However, this technique often suffers from output power fluctuation owing to the cross-interference among receivers as well as the manufacturing and aging tolerance of the resonant frequency (i.e., resonant frequency tolerance). This article proposes an autonomous RIC-WPT system concept to solve this difficulty. The proposed concept addresses the cross-interference and resonant frequency tolerance by incorporating the following two functions. First, the amplitude of the transmitter current is controlled to have a constant amplitude. Second, the phase of each receiver current is controlled to be orthogonal to that of the transmitter current by using an active reactance compensator installed in each receiver. The experiment of a two-receiver RIC-WPT system successfully verified that the two functions of the proposed system concept can stabilize the output voltage against the cross-interference and resonant frequency tolerance.

Quantum dots (QDs) light-emitting diodes (QLEDs) are considered the most promising candidate for application in displays. While the efficiency of QLEDs has been greatly developed in recent years and is comparable to that of organic light-emitting diodes (OLEDs), it still remains challenging to realize both high efficiency and long lifetimes. In this work, we report efficient and stable red QLEDs with the maximum current efficiency of 13.48 cd A-1, external quantum efficiency of 18.65%, and low efficiency roll-off at high luminance with a long lifetime exceeding ∼2.9 × 105 h, representing a 3-fold increase in stability. Tailoring the composition of QDs suppresses nonradiative Forster resonant energy transfer and Auger recombination and provides favorable valence band alignment to boost the hole injection. Our work suggests that tailoring the nanostructures of QDs offers an effective means to simultaneously achieve high efficiency and high stability, accelerating QLED technology for practical applications in displays and lighting.

A cold Rydberg gas, with its atoms prepared initially all in the excited state |n0> , with n0 »1, contains an excessive amount of energy, and presumably is to relax by the Penning-type molecular auto-ionization (MAI), in which a portion of excess energy of one atom is given to another near-by atom and ionizing it. Its complementary process, the resonant energy transfer (RET), is discussed, in which the excess energy of one atom is used on another to form a hyper-excited atomic state |na> with na»n0. This process is always present, provided certain resonance energy conditions are satisfied. In this report, the n0 and density dependences of the RET rates are studied in detail, employing a simple model: 1) at low densities, the RET is mediated by the dipole-dipole coupling Vdd and its rates are generally much smaller than that of MAI, especially for small n0. But 2) as the density increases, our model shows that the rates become of comparable magnitude or even larger than the MAI rates. The Vdd is no longer adequate. We, then construct a semi-empirical potential to describe the RET process. 3) At high densities, we show that the atomic orbital of |na> overlaps with that of neighboring atoms, and the electron-electron potential becomes prominent, resulting in much higher rates.

Triplet state harvesting using thermally-activated delayed fluorescence (TADF) combined with efficient Forster resonant energy transfer (FRET) to a narrow fluorescent emitter is seen as a promising approach to achieve high efficiency and colour-purity in organic light-emitting diodes (OLEDs). In this work, we perform quantum chemistry and quantum dynamics simulations to model the so-called hyperfluorescence (HF) process between a carbene–metal–amide (CMA) molecule with a Au bridging metal (Au-Cz) and a narrow blue fluorescent emitter, 2,5,8,11-tetra-tert-butylperylene (TBPe). Our quantum dynamics simulations illustrate a FRET rate of ∼1010 s−1 indicating that it occurs on the picosecond timescale comparable with the ISC crossing rate of Au-Cz. This high FRET rate, which is most strongly dependent on the energy difference between the S1 states of the donor and acceptor molecules, is advantageous for devices as it encourages rapid triplet harvesting. In addition, the comparable FRET and intersystem crossing (ISC) rates, in contrast to most organic only systems, would facilitate studying this mechanism using photoexcitation. Besides the FRET rate, Forster radii are also estimated from the quantum dynamics simulations for different energy differences between the donor and acceptor molecules and are in quantitative agreement with the experimental estimations for different systems, showing that quantum nuclear dynamics simulation could be an important tool for enhancing our understanding of hyperfluorescence-based emitters.

Electrocatalysis plays a vital role in energy conversion and storage in modern society. Localized surface plasmon resonance (LSPR) is a highly attractive approach to enhance the electrocatalytic activity and selectivity with solar energy. LSPR excitation can induce the transfer of hot electrons and holes, electromagnetic field enhancement, lattice heating, resonant energy transfer and scattering, in turn boosting a variety of electrocatalytic reactions. Although the LSPR-mediated electrocatalysis has been investigated, the underlying mechanism has not been well explained. Moreover, the efficiency is strongly dependent on the structure and composition of plasmonic metals. In this review, the currently proposed mechanisms for plasmon-mediated electrocatalysis are introduced and the preparation methods to design supported plasmonic nanostructures and related electrodes are summarized. In addition, we focus on the characterization strategies used for verifying and differentiating LSPR mechanisms involved at the electrochemical interface. Following that are highlights of representative examples of direct plasmonic metal-driven and indirect plasmon-enhanced electrocatalytic reactions. Finally, this review concludes with a discussion on the remaining challenges and future opportunities for coupling LSPR with electrocatalysis.

Ferrite Encumbered inductive coupling-based energy transmission is interestingly being investigated both theoretically and experimentally as an alternative technique of delivering power through human skin and body for wireless excitation of implantable electronic devices. In the explored system, to enhance the efficiency, the magnetic flux produced by the transmitting coil can be improved focused through the ferrite loaded printed receiving coil by cautious symmetrical placement of ferrite materials. The properties of ferrites include high magnetic permeability and high electrical resistance. In this paper, a ferrite configuration is estimated using Finite Element Method, and an efficient model is nominated for construction and laboratory testing. The proposed technique entails an energy transfer efficiency of ∼48.2% at maximum output power of 248 mW and resonant frequency of 120 kHz over a separation gap of 3 cm. The real-time body temperature of human has been recorded through the energized temperature sensor and corroborated with a calibrated system which ensures the precision of the developed prototype system. The real time data collected in the laboratory are in good agreement with the simulation results, which specify that the laboratory physical prototype and circuit closely followed to the physical and electrical parameters of the simulation. The ferrite loaded resonant inductive coupling technique is considered as a feasible and supportive substitute to the conventional technique for implantable electronic sensors.

The purpose of this work was to propose and theoretically substantiate the fundamental operability of the reactive power transformer circuit, consisting of two series resonant circuits with an adjustable level of electromagnetic coupling between them. Basic analytical expressions for the characteristics of electromagnetic processes in the circuit of the adopted resonant converter are obtained. It is shown that the maximum possible amplification factor of electric reactive power is proportional to the quality factor of the secondary circuit of the transformer. The reliability of the results obtained is confirmed by the conducted experimental studies. Their results showed that the discrepancies between theoretical estimates and experimental data are rather insignificant, and they can be explained by the influence of external electromagnetic fields (superposition of the fields of the "output" solenoid and the coupling transformer). In general, the results obtained illustrate the real possibilities of multiple amplification of reactive electrical power in the proposed resonant transformer circuit. Further work involves the development and creation of a converter of reactive electrical energy into active energy.

A multiscale approach to the dynamics of resonant energy transfer (RET) is presented, combining DFT and TD-DFT results on the energy donor (D) and acceptor (A) moieties with an extensive equilibrium and non-equilibrium molecular dynamics (MD) analysis of a bound D–A pair in solution to build a coarse-grained kinetic model. We demonstrate that a thorough MD study is needed to properly address RET: the enormous configuration space visited by the system cannot be reliably sampled accounting only for a few representative configurations. Moreover, the conformational motion of the RET pair, occurring in a similar time scale as the RET process itself, leads to a sizable increase of the overall process efficiency.

O facto de a energia elétrica ser um tópico de discussão global, faz com que a transmissão de energia sem fios torne-se cada vez mais relevante devido às vantagens que esta apresenta nas suas aplicações. Nesta dissertação é estudado e implementado um modelo de um circuito de transferência de energia sem fios através de uma simulação computacional e um protótipo preparado para fazer a transmissão de energia sem fios por acoplamento indutivo ressonante. A parte fundamental do sistema proposto integra dois pares ressonantes de condensadores e bobinas. O circuito de potência utilizado baseia-se numa ponte H utilizada normalmente para motores de corrente contínua. Para o controlo aplicado à ponte H é utilizada uma função oscilante presente no Arduíno cuja frequência de oscilação pode ser regulada de acordo com a frequência de ressonância do circuito. Foram feitas as aquisições de resultados em contexto experimental, os quais são comparados com a simulação realizada no programa MATLAB, respeitando as condições da topologia inicialmente escolhida. The fact that electrical energy is a topic of global discussion, makes wireless energy transmission increasingly relevant due to the advantages it presents in its applications. In this thesis, a model of a wireless energy transfer circuit is studied and implemented through a computer simulation and a prototype prepared for wireless energy transmission by inductive resonant coupling. The fundamental part of the proposed system integrates two resonant LC circuit. The power circuit used is based on an H-bridge normally used for direct current motors. For the control applied to bridge H, an oscillating function present in the Arduino is used, whose oscillation frequency can be regulated according to the resonant frequency of the circuit. The acquisitions of results were made in an experimental context and compared with the study carried out in the MATLAB program, respecting the conditions of the initially chosen topology.

Con el fin de reducir tamaño y peso, se han venido implementando alternativas para escalar niveles de tensión de la red eléctrica, manteniendo alta eficiencia y baja distorsión. El propósito de este artículo es presentar los resultados del diseño y construcción de un transformador electrónico controlado por un microcontrolador (μC). Se realizó la caracterización de un transformador resonante con núcleo de ferrita, y simulaciones con los modelos reales de los dispositivos electrónicos para validar la etapa de diseño. Se construyó un prototipo que conmuta a diferentes frecuencias con tiempo muerto de 2µs, obteniendo como resultado, una señal a la salida de 12Vrms que opera para cargas resistivas que consuman de 0 a 50W con una eficiencia ( ) aproximada de 94%. Los resultados muestran la viabilidad de desarrollar transformadores electrónicos programables que permiten, a diferencia de los transformadores electrónicos resonantes, entregar cualquier valor de potencia sin depender de la carga.

Series–series (SS) and series–parallel (SP) topologies are widely used in resonant inductive coupling wireless power transfer systems for various applications. However, the selection of an appropriate topology to achieve higher output power or higher efficiency is typically difficult because design optimization of the circuit parameters (e.g., characteristic impedance, load resistance, and mutual inductance) for each topology is generally separately discussed using different equivalent circuits with multiple resonance modes. Therefore, the purpose of this study involves proposing a simple strategy to select an appropriate topology. The proposed strategy is based on quasi-duality between the SS and SP topologies that are elucidated from the novel equivalent circuits derived using Lagrangian dynamics. Based on the quasi-duality, the output power and efficiency of the SP topology are calculated via the equivalent circuit of SS topology. Thus, the quasi-duality offers a simple comparison between the SS and SP topologies. The proposed strategy selects an appropriate topology by comparing only the equivalent ac load resistance, which is the ac resistance including the rectifying circuit and the load resistance, the characteristic impedance, and the ac load resistance that achieves the maximum efficiency or maximum output power of the SS topology. Experiments verify the appropriateness and effectiveness of the proposed strategy.

International audience; Fluorescent emitters like ions, dye molecules or semiconductor nanoparticles are widely used in opto-electronic devices, usually within densely-packed layers. Their luminescence properties can then be very different from when they are isolated, because of short-range interparticle interactions such as Förster resonant energy transfer (FRET). Understanding these interactions is crucial to mitigate FRET-related losses and could also lead to new energy transfer strategies. Exciton migration by FRET hopping between consecutive neighbor fluorophores has been evidenced in various systems but was generally limited to distances of tens of nanometers and involved only a few emitters. Here we image self-assembled linear chains of CdSe nanoplatelets (colloidal quantum wells) and demonstrate exciton migration over 500-nm distances, corresponding to FRET hopping over 90 platelets. By comparing a diffusion-equation model to our experimental data, we measure a (1.5 ps)-1 FRET rate, much faster than all decay mechanisms, so that strong FRET-mediated collective photophysical effects can be expected. FRET is a non-radiative energy transfer mechanism by electromagnetic dipole-dipole coupling 1. FRET energy migration plays a key role in photosynthesis by funneling photogenerated excitons from the light harvesting centers to the reaction center 2. Systems of dyes attached to DNA scaffolds have been engineered in order to create FRET-based bio-inspired 30-nm photonic wires 3 and logic gates 4. In opto-electronics, FRET must be understood as it may be detrimental by funneling excitonic energy to quenching sites, but it can also favor efficient charge collection in photovoltaic cells and lead to new FRET-enabled excitonic devices 5. With this in mind, exciton migration has been explored in various systems. In molecular or polymer systems, migration by incoherent FRET hopping was generally demonstrated over a few tens of nanometers 6-8 (while distances of hundreds of nanometers or microns could be reached by other mechanisms such as Dexter hopping and coherent exciton motion 6,9-10 and by a combination of coherent and incoherent exciton motion in the case of J-and H-aggregates 11, 35, 36). Within quantum dot films, various methods were developed for the delicate characterization of FRET exciton migration 12 and yielded diffusion distances of 10-30

This study presents the design of an efficient, moderately high gain and portable antenna operating at 58.27 MHz. The proposed antenna is a multilayered hemi-cylindrical shaped structure, which works on the principle of resonant inductive coupling using a multi-turn loop. An equivalent circuit, which takes into account the near field coupling effects, is also developed. The proposed antenna is electrically small with a finite ground plane with k a ≃ 0.28 and has an overall volume of 0.038λ0 × 0.058λ0 × 0.058λ0. The antenna exhibits a gain of 3.43 dBi and an efficiency of 92.5% as obtained from measured results at the resonant frequency. The measured fractional bandwidth and the Q ratio of the antenna are 0.547 and 8.647%, respectively. The results obtained from electromagnetic simulation matches with that obtained from the equivalent circuit and the measured results. The antenna can operate at the lower very high frequency (VHF) frequency range for applications, which require electrically small portable antennas such as underground mine communication.

In this work, we demonstrate efficient light down-conversion via FRET in InGaN/GaN multiple quantum well (MQW) nanohole arrays, coated with green-emitting CsPbBr3 and FAPbBr3 nanocrystals (NCs) and near-infrared (IR) FAPbI3 NC overlayers for solid-state lighting. Patterning the InGaN MQW into nanohole arrays allows a minimum nitride–NC separation while increasing the heterointerfacial area, thus improving simultaneously the nonradiative and radiative transfer efficiencies. Detailed spectroscopic studies of steady-state and time-resolved photoluminescence indicate a significant reduction in the quantum well photoluminescent decay time in the presence of NCs, accompanied by a significant concurrent increase of the NC integrated emission, providing evidence of efficient light down-conversion mediated by FRET with efficiencies as high as ∼83 ± 6% in the green and ∼74 ± 5% in the near-IR., ACS Applied Nano Materials, 3 (3), ISSN:2574-0970

Non-radiative processes like energy and charge transfer in 0D–2D semiconductor quantum dot (QD)-transition metal dichalcogenides (TMDs) and other two-dimensional layered materials, like graphene and analogs, leading to strong quenching of the photoluminescence (PL) of the usually highly emissive QDs, have been widely studied. Here we report control of the emission efficiency of core QDs placed in close proximity to the monolayers of MoS2. The QDs are transferred in the form of a high-density compact monolayer with the dot–dot separation, δ as well as the MoS2–QD separation, d, being controlled through chemical methods. While at larger separations we observe some quenching due to non-radiative processes, at smaller separations we observe enhanced emission from QDs on MoS2 as compared to the reference despite the presence of significant non-radiative charge transfer. Interestingly, at small separations δ, we see evidence of strong dot–dot interactions and a significant red shift of QD PL which enhances spectral overlap with the B exciton of MoS2. However, we observe significant reduction of PL quenching of QDs relative to longer δ and d cases, despite increased probability of non-radiative resonant energy transfer to MoS2, due to the enhanced spectral overlap, as well as charge transfer. Significantly we observe that simultaneously the intensity of the B exciton of MoS2 increases significantly suggesting the possibility of coherent and resonant radiative energy exchange between the 0D excitons in QDs and the 2D B exciton in MoS2. Our study reveals interesting nanoscale light–matter interaction effects which can suppress quenching of QDs leading to potential applications of these nanoscale materials in light emitting and photonic devices.

Evidence of composition dependent efficient Forster resonance energy transfer (FRET) between ZnS (donor) and CdS (acceptor) has been demonstrated in hexagonal ternary Cd(1−x)ZnxS nanomaterials synthesized by a chemical co-precipitation method. An agglomerated nanoparticulate morphology made of quantum dot like crystallites has been observed for all compositions. Analysis of the current–voltage characteristics of the samples reveals a gradual increase and then a decrease from a higher to a lower conductive state with the increase of the Zn content, displaying a variation from non-linear to linear characteristics. The tunability in the energy band gap has an increasing trend with the increase in the Zn/Cd ratio in Cd(1−x)ZnxS. The tunable emission varies from the green to the violet region with their intensity maxima increasing with the increase in Zn concentration. Significant spectral overlap between the absorbance spectrum of CdS and the photoluminescence spectrum of ZnS indicates FRET in Cd(1−x)ZnxS. The calculated energy transfer efficiencies vary from 65.7% to 89%, the Forster distances are confined within the range 11.13–14.77 A and the inter donor–acceptor distances are limited to 14.29–71.4 A. To get insight, electroluminescent efficiencies have been calculated using a theoretical model if Cd(1−x)ZnxS is used as emissive materials in LED devices. Cd0.5Zn0.5S nanomaterials have shown maximum external electroluminescence efficiency at low operating voltage. Hence, the FRET based tunable photoluminescence coupled with the observed electrical properties of Cd(1−x)ZnxS shows remarkable promise for their application in optoelectronic devices.

Fluorescence quantum dots (QDs) are promising functional nanomaterials in chemical biology and environmental applications, where an analyte-induced responsive system is beneficial for detecting numerous life-related molecules and pollutants. Here, fluorescent Ti3C2 MXene quantum dots (MQDs) with the size of 1.75 nm were synthesized by a simple method of hydrofluoric acid etching and dimethyl sulfoxide exfoliation to form nanosheets followed by a one-step ultrasound method. The as-synthesized MQDs showed excitation-dependent behaviour along with a fluorescence quantum yield value of 7.7%. In addition, the fluorescence of the MQDs can be significantly suppressed by Fe3+. The mechanism for the fluorescence quenching of the MQDs was systematically investigated, which was attributed to the oxidation-reduction reaction between the MQDs and Fe3+ and the inner filter effect (IFE), different from the reported Forster resonant energy transfer (FRET) mechanism for MXene nanosheets. Based on this trait, a fluorescence method for Fe3+ detection based on MQDs was demonstrated with high sensitivity and selectivity, and the limit of detection was 310 nM. The proposed method was successfully used for the sensitive detection of Fe3+ in serum and sea water. This work will not only help to understand the selectivity mechanisms of MQDs as fluorescent probes for metal ions, but also provide a smart sensing platform in biological and environmental detection.

Temperature plays some significant role in biological processes. Electromagnetic energy could be related to temperature. Here, we have established the relationship between temperature role in living biological processes and Resonant Recognition Model, which proposes that proteins specific biological activity is based on electromagnetic resonant energy transfer.Read Complete Article at ijSciences: V92020032316 AND DOI: http://dx.doi.org/10.18483/ijSci.2316

The design of dynamic wearable wireless power transfer systems (WPT) possesses multiple challenges that affect the WPT efficiency. The varying operation conditions, such as the coils' coupling, and operation in proximity or through the human body, can affect the impedance matching at the resonant frequency. This paper presents a high-efficiency wearable 6.78 MHz WPT system for smart cycling applications. Resonant inductive coupling using dual-receiver textile coils is proposed for separation-independent WPT, demonstrated in a smart cycling glove, for transferring energy from an on-bicycle generator to smart-textile sensors. The effects of over-coupling in a dynamic WPT system have been investigated analytically and experimentally. The embroidered coils efficiency is studied in space, on- and through-body. The measured results, in space, show around 90% agreement between the analytical and experimental results. To overcome frequency-splitting in the over-coupling region, an asymmetric dual-receiver architecture is proposed. Empirical tuning of the lumped capacitors is utilized to achieve resonance at 6.78 MHz between the fundamental frequency and the even mode split frequency. Two different coil sizes are utilized to achieve separation-independent efficiency in the tight coupling region on- and off-body, while maintaining a Specific Absorption Rate (SAR) under 0.103 W/kg. The presented system achieves a peak efficiency of 90% and 82% in free space and on-hand respectively, with a minimum efficiency of 50% under loose and tight coupling, demonstrating more than 40% efficiency improvement over a 1:1 symmetric transmit and receive coil at the same separation.

Resonance energy transfer (RET), at the heart of photosynthesis, supports life on earth, but also guarantees the operation of several technological devices, like organic light-emitting diodes and solar cells. Medium properties and dynamics largely affect RET efficiency, but reliable models addressing how molecular electron-vibration motion and solvent dynamics jointly affect RET are still missing. Here we propose a novel quantum-classical approach to describe RET in a non-adiabatic molecular system embedded in a dynamic polar environment. The approach, validated against optical properties of a dye in solution, is then applied to a RET-pair, demonstrating that dynamic disorder, as induced by a liquid polar solvent, boosts RET efficiency.

Understanding the nonradiative Forster resonance energy transfer (FRET) in molecular conjugate systems mediated by nanophotonics is a new research direction in developing and optimizing photovoltai...

The conversion of a high-energy photon into two excitons using singlet fission (SF) has stimulated a variety of studies in fields from fundamental physics to device applications. However, efficient SF has only been achieved in limited systems, such as solid crystals and covalent dimers. Here, we established a novel system by assembling 4-(6,13-bis(2-(triisopropylsilyl)ethynyl)pentacen-2-yl)benzoic acid (Pc) chromophores on nanosized CdTe quantum dots (QDs). A near-unity SF (198 ± 5.7%) initiated by interfacial resonant energy transfer from CdTe to surface Pc was obtained. The unique arrangement of Pc determined by the surface atomic configuration of QDs is the key factor realizing unity SF. The triplet-triplet annihilation was remarkably suppressed due to the rapid dissociation of triplet pairs, leading to long-lived free triplets. In addition, the low light-harvesting ability of Pc in the visible region was promoted by the efficient energy transfer (99 ± 5.8%) from the QDs to Pc. The synergistically enhanced light-harvesting ability, high triplet yield, and long-lived triplet lifetime of the SF system on nanointerfaces could pave the way for an unmatched advantage of SF. acceptedVersion

In this work we presented novel strategy for increasing the performance of popular fluorescent probes on the basis of rhodamine-lactam platform. This strategy is based on the incorporation of probe molecules into the light-harvesting nanoparticles to pump modulated optical signal by Förster resonant energy transfer. Using the commercially available Cu2+ probe as a reference chemical, we have developed an efficient approach to significantly improve its sensing performance. Within obtained nanoparticles coumarin-30 nanoantenna absorbs excitation light and pumps incorporated sensing molecules providing bright fluorescence to a small number of emitters, while changing the probe-analyte equilibrium from liquid-liquid to solid-liquid significantly increased the apparent association constant, which together provided a ~100-fold decrease in the detection limit. The developed nanoprobe allows highly sensitive detection of Cu2+ ions in aqueous media without organic co-solvents usually required for dissolution of the probe, and demonstrate compatibility with inexpensive fluorometers and the ability to detect low concentrations with the naked eye.

The resonant inductive coupling wireless power transfer technique (RIC-WPT) is emerging as a promising wireless power transfer method for small mobile devices with comparatively high-power transfer capability and good efficiency. However, the performance of the RIC-WPT system is severely deteriorated by the resonant frequency detuning of the transmitter, repeater, and receiver resonators, which can be naturally caused by the manufacturing tolerance and the aging effect of these resonators. Particularly, the detuning of the repeater resonator tends to severely affect the performance due to its high-quality factor, which should be solved for practical application of RIC-WPT technology. This paper addresses this difficulty by proposing an autonomous resonant frequency tuning controller circuit for the repeater resonator. The controller tunes the resonant frequency of the repeater resonator to the operating frequency of the inverter, driving the transmitter, without an external power supply and wireless communication with the inverter controller, which restricts the freedom of the installation location and therefore preferably be avoided in the wireless power transfer system. The operating principles of the proposed controller were confirmed by the circuit simulator, supporting the feasibility of the proposed controller.

A full-color whispering-gallery mode (WGM) laser has been fabricated by partitioning different light-emitting polymers in a nested microcavity. Red-green-blue WGM lasing with a high quality factor above 104 and a narrow linewidth of 0.025 nm emits from nested capillaries when excited with a nanosecond laser. The full-color WGM lasing shows a low excitation threshold for the nested microcavities, which can avoid fluorescence resonant energy transfer. We also achieve wavelength tunable lasing upon altering the different polymers in the nested microcavities. The work demonstrates a simple method to fabricate a full-color WGM laser and its potential applications in compact lighting devices and white laser sources.

Early monitoring of prostate-specific antigen (PSA) is crucial in diagnosis and proactive treatment of prostate disease. Herein, a dual-quenching ternary ECL immunosensor was designed for PSA detection based on graphitic carbon nitride quantum dots (g-CNQDs, as an emitter), potassium persulfate (K2S2O8, as a coreactant), and silver nanoparticles doped multilayer Ti3C2 MXene hybrids (Ag@TCM, as a coreaction accelerator). First, Ag@TCM was immobilized on the surface of a glassy carbon electrode, then g-CNQDs was further adsorbed on Ag@TCM to acquire a higher initial ECL signal at a potential window from − 1.3 to 0.0 V (vs. Ag/AgCl). Ag@TCM not only acted as the coreaction accelerator, but also as a matrix to load enormous g-CNQDs and prostate-specific capture antibody via Ag–N bond. Meanwhile, prostate-specific detection antibody was marked by gold nanoparticles modified manganese dioxide as a dual-quenching probe (Ab2- Au@MnO2). When Ab2-Au@MnO2 was introduced into the ternary ECL system via sandwiched immuno-reaction, the high-sensitive detection of PSA was achieved by the dual-quenching effect, caused by the resonant energy transfer from g-CNQDs (energy donor) to Au@MnO2 (energy acceptor). As a result, this ECL immunosensor showed a good dynamic concentration range from 10 fg·mL−1 to 100 ng·mL−1 with a detection limit of 6.9 fg·mL−1 for PSA detection. The dual-quenching ECL strategy presented high stability and good specificity to open up a new pathway for ultrasensitive immunoassay.

We propose a scheme utilizing the double plasmon modes of gold nanorods (GNRs) to efficiently increase the Forster resonant energy transfer (FRET) efficiency and enhance the photoluminescence (PL) of Si quantum dots (Si QDs) nearby. Detailed PL and decay dynamics studies are performed for the hybrid nanostructures composed of metallic nanoparticles (MNPs) coated with a Si QD-absorbed silica shell. Plasmon enhanced FRET between Si QDs has been observed and proposed as the third enhancement mechanism for the plasmon-enhanced photoluminescence in addition to excitation enhancement and emission enhancement mechanisms. A maximum FRET efficiency of 46.3% is obtained, which is enhanced by a factor of 8.7 compared to that of samples without MNPs. The dependence of the energy transfer efficiency and the enhancement of the acceptor emission on the surface plasmon resonance (SPR) wavelength, metal-QD distance and QD ratio is examined. The FRET enhancement mechanism dominates when the coupling of plasmon-donor is much stronger than that of plasmon-acceptor with a high acceptor/donor ratio.

We first design and fabricate a highly efficient integrated CuWO4/Ag/BiOI device for photoelctrochemical water splitting. In this system, the formation of a p-n heterojunction between CuWO4/BiOI facilitates the carriers separation and transportation through built-in electrical field. Meanwhile, the Ag nanoparticles (NPs) own surface plasmon resonance (SPR), which increase the photoelectrochemical activity by transfer energy to metal oxides via hot electrons transfer (HET) and plasmon resonant energy transfer (PRET). As expected, this novel ternary CuWO4/Ag/BiOI structure reveals a dramatically promoted photocurrent of 2.10 mA/cm2 at 1.23 V vs. RHE in photoelctrochemical water splitting, which is higher than that of bare CuWO4. Hence, this work may provide an avenue guidelines for p-n heterojunction and plasmon synergistically enhance photoelctrochemical water splitting.

Resonant inductive coupling wireless power transfer is widely known to be a possible convenient power supply method for the small mobile apparatus. However, the limited receiving-coil size tends to lower the efficiency and limit the output power owing to the small mutual inductance and comparatively large stray alternating current (AC) resistance of the receiving-coil. This study mitigates this issue by proposing a novel receiving-coil structure. This proposed structure comprises a coil and a drum core with a thin axis. The coil is wound on the axis to form a single winding layer. The proposed structure can reduce stray AC resistance by suppressing the proximity effect and reducing the wire length without deteriorating the mutual inductance significantly. Therefore, better efficiency and larger output power can be achieved. Simulations and experiments were performed to verify the proposed structure. Consequently, both simulations and experiments supported the reduction in AC resistance compared to the conventional structure. Furthermore, the experiment revealed improvements by the proposed structure in both efficiency and output power. These results support the effectiveness of the proposed structure for wireless power transfer to small mobile apparatus.

Correlated light and electron microscopy (CLEM) has become a popular technique for combining the protein-specific labeling of fluorescence with electron microscopy, both at room and cryogenic temperatures. Fluorescence applications at cryo-temperatures have typically been limited to localization of tagged protein oligomers due to known issues of extended triplet state duration, spectral shifts, and reduced photon capture through cryo-CLEM objectives. Here, we consider fluorophore characteristics and behaviors that could enable more extended applications. We describe how dialkylcarbocanine DiD, and its autoquenching by resonant energy transfer (RET), can be used to distinguish the fusion state of a lipid bilayer at cryo-temperatures. By adapting an established fusion assay to work under cryo-CLEM conditions, we identified areas of fusion between influenza virus-like particles and fluorescently labeled lipid vesicles on a cryo-EM grid. This result demonstrates that cryo-CLEM can be used to localize functions in addition to tagged proteins, and that fluorescence autoquenching by RET can be incorporated successfully into cryo-CLEM approaches. In the case of membrane fusion applications, this method provides both an orthogonal confirmation of functional state independent of the morphological description from cryo-EM and a way to bridge room-temperature kinetic assays and the cryo-EM images.

A series of Ce3+, Tb3+ and Yb3+ tri-doped feldspar CaAl2Si2O8 (CASO) phosphors have been successfully synthesized at ∼ 1350 °C under reducing atmosphere. Optical properties of these phosphors have been investigated as a function of doping concentrations by using fluorescence spectra and decay lifetime analysis in detail. The XRD patterns and structure refinements indicate that the dopants do not change the phase structure of host lattice. For Ce3+/Tb3+/Yb3+ all occupied at Ca2+ sites, charge compensation requires cationic vacancies ( V C a / / ) to maintain electrical neutrality instead of oxygen at interstitial site ( O i 2 − ) because the phosphors were synthesized under reducing atmosphere. The near ultraviolet (n-UV) converted to near-infrared (NIR) emission of the aluminosilicate phosphors have achieved via Ce3+ → Tb3+ → Yb3+ resonant energy transfer (ET), enabling their potential application as down-conversion (DC) converter in Si-based solar cells. The role of Tb3+ is acting as ET bridge to connect Ce3+ and Yb3+ ion pairs. Through adjusting optimal doping concentrations, these NIR DC phosphors can exhibit excitation bands in n-UV region and strong NIR emissions.

Silicon carbide (SiC) has been extensively investigated in the last decade, specifically for applications in harsh environments. However, most SiC sensors require an external power supply, which cannot operate at high temperatures. This letter develops a new sensing technology in a SiC platform based on near field communication to eliminate the requirement for wired power sources. The 3C-SiC temperature sensors were fabricated from a SiC-on-insulator substrate formed by anodic bonding. The sensors functioned based on the thermoresistance of the SiC films with the high TCR of −13 000 ppm/K at 300 K and −3 000 ppm/K at 600 K. The resistance change of the sensors was wirelessly measured using a reading coil placed outside of the heating chamber, showing a significant resonant-frequency-shift (−400 ppm/K at 600 K) of the coupling impedance under temperature variation. The proposed technique is promising for the development of wireless wide-band-gap sensors used in extreme conditions.

In this paper, we demonstrated trace of dye molecules in living plants. The NaGdF4:Yb3+,Er3+ nanoparticles probe was used to detect the rhodamine B (RhB) in bean sprout. It is found that the fluorescencedye can be efficiently imbibed during the growing process and the absorbance presented a position dependence effect, which was supported by the upconversion spectra and the fluorescent image characterization. In addition, the concentration of the residual RhB in bean sprout can be efficiently traced by the synthesized probe based on the fluorescent resonant energy transfer. Finally, the relation between the excitation power, concentration and the ratio of yellow to green emission are discussed in detail. These results can be helpful in understanding the RhB dye molecules absorbance process in vegetable growth and provide an efficient way to trace the residual dyes in vivo plant.