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We present an optical method that combines confocal microscopy with position modulation to perform axial tracking and topographic imaging of fluorescent surfaces. Using a remote focusing system, the confocal observation volume is oscillated in the axial direction. The resulting modulation of the detected signal is used as a feedback to precisely control the distance to an object of interest. The accuracy of this method is theoretically analyzed and the axial-locking accuracy is experimentally evaluated. Topographic imaging is demonstrated on fluorescently coated beads and fixed cells. This microscope allows for nanometric topography or tracking of dynamic fluorescent surfaces.

An M13 bacteriophage-based Förster resonance energy transfer (FRET) system is developed to estimate intermolecular distance at the nanoscale using a complex of CdSSe/ZnS nanocrystal quantum dots, genetically engineered M13 bacteriophages labeled with fluorescein isothiocyanate and trinitrotoluene (TNT) as an inhibitor. In the absence of trinitrotoluene, it is observed that a significant spectral shift from blue to green occur, which represents efficient energy transfer through dipole-dipole coupling between donor and acceptor, or FRET-on mode. On the other hand, in the presence of trinitrotoluene, the energy transfer is suppressed, since the donor-to-acceptor intermolecular distance is detuned by the specific capturing of TNT by the M13 bacteriophage, denoted as FRET-off mode. These noble features are confirmed by changes in the fluorescence intensity and the fluorescence decay curve. TNT addition to our system results in reducing the total energy transfer efficiency considerably from 16.1% to 7.6% compared to that in the non-TNT condition, while the exciton decay rate is significantly enhanced. In particular, we confirm that the energy transfer efficiency satisfies the original intermolecular distance dependence of FRET. The relative donor-to-acceptor distance is changed from 70.03 Å to 80.61 Å by inclusion of TNT.

We have employed a variable stripe length method in order to measure the optical gain of GaAs/AlGaAs quantum rings. Although the large lateral diameter of quantum rings ( ∼ 50 nm) with a few nm size distribution is expected to cause a small spectral inhomogeneity ( ∼ 1 %), a broad gain width ( ∼ 300 meV) was observed. This result was attributed to a variation of the vertical heights and variations in localized states that exhibit crescent shaped wavefunctions, whereby the energy levels are distributed over a broad spectral range. When the excitation intensity is decreased, irregular peaks appear in the gain spectrum gradually. Similar phenomena were also observed as the temperature increased. We conclude that excited carriers in quantum rings are distributed stochastically at various localized states and that the population inversion is sensitive to both excitation intensity and temperature.

We find that the emission from laterally coupled quantum dots is strongly polarized along the coupled direction [1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar 1$$\end{document}1¯0], and its polarization anisotropy can be shaped by changing the orientation of the polarized excitation. When the nonresonant excitation is linearly polarized perpendicular to the coupled direction [110], excitons (X1 and X2) and local biexcitons (X1X1 and X2X2) from the two separate quantum dots (QD1 and QD2) show emission anisotropy with a small degree of polarization (10%). On the other hand, when the excitation polarization is parallel to the coupled direction [1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar 1$$\end{document}1¯0], the polarization anisotropy of excitons, local biexcitons, and coupled biexcitons (X1X2) is enhanced with a degree of polarization of 74%. We also observed a consistent anisotropy in the time-resolved photoluminescence. The decay rate of the polarized photoluminescence intensity along the coupled direction is relatively high, but the anisotropic decay rate can be modified by changing the orientation of the polarized excitation. An energy difference is also observed between the polarized emission spectra parallel and perpendicular to the coupled direction, and it increases by up to three times by changing the excitation polarization orientation from [110] to [1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar 1$$\end{document}1¯0]. These results suggest that the dipole–dipole interaction across the two separate quantum dots is mediated and that the anisotropic wavefunctions of the excitons and biexcitons are shaped by the excitation polarization., Quantum dots: coupled control New information storage technologies could use polarized light to control the optical properties of coupled quantum dots. The idea of combining quantum dots – nanoscale semiconductor crystals – into coupled pairs has attracted great attention due to the increased number of exotic quantum states that can be realized for storing data. Robert Taylor at the University of Oxford, UK, with co-workers in China and Korea, directed polarized laser light onto coupled gallium arsenide quantum dots to induce photoluminescence. They found that the emitted light showed very different characteristics depending on whether the excitation was parallel or at right angles to the line formed by the two dots. This ‘optical shaping’ reflects different arrangements of excitons – bound states of electrons and holes – in the coupled dots, and could open new avenues for data storage and thermoelectric energy harvesting.

We found that optical Aharonov–Bohm oscillations in a single GaAs/GaAlAs quantum ring can be controlled by excitation intensity. With a weak excitation intensity of 1.2 kW cm–2, the optical Aharonov–Bohm oscillation period of biexcitons was observed to be half that of excitons in accordance with the period expected for a two-exciton Wigner molecule. When the excitation intensity is increased by an order of magnitude (12 kW cm–2), a gradual deviation of the Wigner molecule condition occurs with decreased oscillation periods and diamagnetic coefficients for both excitons and biexcitons along with a spectral shift. These results suggest that the effective orbit radii and rim widths of electrons and holes in a single quantum ring can be modified by light intensity via photoexcited carriers, which are possibly trapped at interface defects resulting in a local electric field.

We have performed time-resolved photoluminescence of dilute GaAs/AlGaAs quantum rings for increasing excitation and temperature. Although a large distance between quantum rings (200 ± 50 nm) prevents a ring-to-ring carrier transport, a decay time difference over the wide spectrum and its change became significant with increased excitation and temperature. Those results were explained in terms of an internal relaxation of the fine levels in a quantum ring structure. As carrier injection is increased, the carrier relaxation of high energy levels becomes enhanced possibly via the state-filling effect and Auger scattering. We also found that the population decay of low energy levels slows down due to a carrier feeding, but the net population of intermediate levels become nearly constant due to a balanced carrier transfer in between the high and low energy levels. For increased temperature, we observed a photoluminescence quenching at the high energy levels as a consequence of a thermal escape from the shallow potential depth.

We demonstrated that radiative recombination rate of CdSe/ZnS nanocrystal quantum dots is enhanced by local surface plasmon of an adjacent Au layer as a consequence of the Purcell effect. I...

A series of inhibitors were incorporated to modulate the detection range of mercury assay. A single-strand DNA-based mercury probe (ssDNA-Hg) containing 5 thymine (T) bases at both termini, which forms a hairpin structure in the presence of mercuric (Hg2+) ions via the T⋯Hg2+⋯T interaction, was designed. Although many previous studies focused on mercury detection to improve the sensitivity and selectivity, few studies have been reported to tune the detection range to cover a wide range of target concentrations in different environments. In the present study, a new Hg2+ detection scheme was designed to extend, narrow and shift the range of mercury detection using inhibitors. The complementary DNA (ssDNA-C) and cationic conjugated polyelectrolyte (CPE) induced a shift or broadening of the spectral response range by functioning as an allosteric inhibitor. Iodide and cyanide ions worked as efficient depletants, adjusting the binding constant of ssDNA-Hg and Hg2+ (1.1 × 107 M−1) by ∼10 times (up to ∼1.4 × 106 M−1) in the presence of I− or CN− ions, resulting in a large shift in the detection range according to [I−] or [CN−] with a sharp titration curve via a sequestration mechanism. Similar Hg2+ detection range shift was successfully demonstrated using same series of inhibitors in real samples such as Han River and tap water. This study suggests that the binding affinity of probe can be tuned toward a target and the resulting detection response range can be controlled using a range of inhibitors.

We have considered optical nonlinearities of coupled quantum dots theoretically, where an exciton dipole-dipole interaction is mediated between the adjacent large and small quantum dots. For increasing a pump pulse area in resonance with the large quantum dot exciton the induced nonlinear refractive index of the small quantum dot exciton has been obtained. As the exciton dipole-dipole interaction depends on the relative orientation of two exciton dipoles, the optical nonlinearities for the directions parallel and perpendicular to the coupling axis of the two quantum dots are compared. The directional imbalance of optical nonlinearities in coupled quantum dots can be utilized for a polarization phase modulator by controlling a pump pulse area and propagation length.

We recently implemented highly sensitive detection systems for photo-sensitizing potassium ions (K+) based on two-step F&ouml, rster resonance energy transfer (FRET). As a successive study for quantitative understanding of energy transfer processes in terms of the exciton population, we investigated the fluorescence decay dynamics in conjugated polymers and an aptamer-based 6-carboxyfluorescein (6-FAM)/6-carboxytetramethylrhodamine (TAMRA) complex. In the presence of K+ ions, the Guanine-rich aptamer enabled efficient two-step resonance energy transfer from conjugated polymers to dyed pairs of 6-FAM and TAMRA through the G-quadruplex phase. Although the fluorescence decay time of TAMRA barely changed, the fluorescence intensity was significantly increased. We also found that 6-FAM showed a decreased exciton population due the compensation of energy transfer to TAMRA by FRET from conjugated polymers, but a fluorescence quenching also occurred concomitantly. Consequently, the fluorescence intensity of TAMRA showed a 4-fold enhancement, where the initial transfer efficiency (~300%) rapidly saturated within ~0.5 ns and the plateau of transfer efficiency (~230%) remained afterward.

A green emitting Ba1.98SiO4−δN2/3δ:Eu0.02 phosphor with an appreciable intensity was synthesized using the gas-reduction–nitridation (GRN) method. SEM revealed agglomerated Ba1.98SiO4−δN2/3δ:Eu0.02 particles with irregular morphologies and a primary particle size of 1–2.5 μm. The phosphor showed emission lines of Eu2+ corresponding to the 4f65d1 → 4f7 transition under 370 nm excitation. As the GRN process was conducted to incorporate N3− into the lattice, both the excitation and emission intensity of Ba1.98SiO4−δN2/3δ:Eu0.02 were enhanced greatly compared to Ba1.98SiO4:Eu0.02. The decay time of Ba1.98SiO4−δN2/3δ:Eu0.02 showed that N entered the Ba1.98SiO4:Eu0.02 lattices to replace O to form a NO point defect. The electroluminescence intensity of Ba1.98SiO4−δN2/3δ:Eu0.02 at 503 nm increased with increasing forward bias current. Intense green LEDs were fabricated by coating the synthesized phosphors on the cap of the near-ultraviolet InGaN LEDs (λem = 375 nm). Overall, this phosphor appears to be a promising candidate for solid-state lighting applications.

The optical Aharonov-Bohm effect in a single quantum ring is associated with disorder effects. In the presence of structure anisotropy, localisation, internal electric field, and impurity scattering, optical Aharonov-Bohm oscillations of an electron-hole pair become modulated. Additionally, provided that a strongly correlated exciton pair is formed in a single quantum ring similar to the Wigner molecule, novel oscillations can be observed for increasing magnetic field. In this case, the biexciton emission energy changes abruptly at transition magnetic fields with a fractional oscillation period compared to that of the exciton, the so-called fractional optical Aharonov-Bohm oscillations.

Optical anisotropy of self-assembled elliptical InP quantum dots has been investigated in terms of the polarization dependence of excitons. Although large size inhomogeneity is present, two kinds of characteristic quantum dots, which are classified into large and small quantum dots, were found in terms of the polarization anisotropy. We have confirmed that the large quantum dots are more pronounced in the polarization anisotropy, where the degree of linear polarization for the large quantum dots is significantly larger (∼60%) than that for the small ones (∼36%). The effective shape of quantum dots is also estimated by using the size dependence of oscillator strength, which is in agreement with the AFM image. We also suggest that the anisotropy of exciton oscillator strength can be modified via the dipole–dipole interaction between nearest exciton dipoles.

Generally confinement size is considered to determine the dimensionality of nanostructures. While the exciton Bohr radius is used as a criterion to define either weak or strong confinement in optical experiments, the binding energy of confined excitons is difficult to measure experimentally. One alternative is to use the temperature dependence of the radiative recombination time, which has been employed previously in quantum wells and quantum wires. A one-dimensional loop structure is often assumed to model quantum rings, but this approximation ceases to be valid when the rim width becomes comparable to the ring radius. We have evaluated the density of states in a single quantum ring by measuring the temperature dependence of the radiative recombination of excitons, where the photoluminescence decay time as a function of temperature was calibrated by using the low temperature integrated intensity and linewidth. We conclude that the quasi-continuous finely-spaced levels arising from the rotation energy give rise to a quasi-one-dimensional density of states, as long as the confined exciton is allowed to rotate around the opening of the anisotropic ring structure, which has a finite rim width.

The combined dynamic process of Forster resonance energy transfer and transient quenching is quantified in the time-resolved fluorescence of cationic polyfluorene/fluorescein-labelled single-stranded DNA complex. We found that the radiation boundary condition fails to predict transient quenching due to a single quenching rate at the encounter distance between a fluorophore and a quencher; however, the predictions of the micellar kinetics model were in good agreement with the measured time-resolved fluorescence as an alternative to the complicated distance-dependent quenching model. The combined dynamics model enables the separation of the rate of Forster resonance energy transfer from that of transient quenching, by which we obtained an accurate estimation of the donor–acceptor intermolecular distance (41±1.6 A) in comparison with the Forster distance (43 A).

We find that the exciton dipole–dipole interaction in a single laterally coupled GaAs/AlGaAs quantum dot structure can be controlled by the linear polarization of a nonresonant optical excitation. When the excitation intensity is increased with the linearly polarized light parallel to the lateral coupling direction [11̅0], excitons (X1 and X2) and local biexcitons (X1X1 and X2X2) of the two separate quantum dots (QD1 and QD2) show a redshift along with coupled biexcitons (X1X2), while neither coupled biexcitons nor a redshift are observed when the polarization of the exciting beam is perpendicular to the coupling direction. The polarization dependence and the redshift are attributed to an optical nonlinearity in the exciton Förster resonant energy transfer interaction, whereby exciton population transfer between the two quantum dots also becomes significant with increasing excitation intensity. We have further distinguished coupled biexcitons from local biexcitons by their large diamagnetic coefficient.

We demonstrate that the Stimulated Emission Depletion (STED) concept, which is usually invoked for fluorescence, can be extended to photoacoustic effects. When two-nanosecond pulses of exciting and stimulating light are synchronized, 80% of the acoustic signal generated through excited state absorption (ESA) can be quenched. Regarding the cross-sections for stimulated emission and ESA, a model gives a good order of magnitude in the depletion efficiency. The transient molecular orientation, usually measured via the fluorescence anisotropy, can be accessed in photoacoustic when STED is implemented.

We have performed a variable stripe length method at 5 K to measure the optical gain of CdS nanowires. When the excited carrier density is lower than the Mott density, we found that various inelastic scatterings of excitons and LO-phonons are involved. As a consequence of inelastic exciton-exciton scattering, the excitons scattered down to the low polariton branch cause P-emission lasing, and the excited excitons also result in a population inversion through intra-relaxation. When LO-phonon scatterings are involved, a broad optical gain spectrum is observed resulting from exciton-LO and P-LO scatterings.

A new potassium ion detection assay was developed using a dye-labeled aptamer and conjugated polyelectrolyte (CPE) as a signaling platform via 1-step and 2-step fluorescence resonance energy transfer. Guanine-rich K+-specific aptamers were designed as K+ ion recognition species with 6-carboxyfluorescein (6-FAM) and 6-carboxytetramethylrhodamine (6-TAMRA) at both termini. In the presence of K+ ions, the aptamers undergo a conformational change from an unfolded to folded form by forming a G-quadruplex with K+, bringing two dyes in proximity. FRET-induced 6-TAMRA emission was proportional to [K+] in a range of 22.5 μm–100 mm in water without interference by the presence of excess Na+ ions (100 mm). Upon the addition of CPE, a two-step FRET process from CPE to 6-TAMRA via 6-FAM was enabled, showing an intensified 6-TAMRA signal with K+ ions. The dynamic detection range and limit of detection (LOD) was fine-tuned from ∼millimolar to ∼nanomolar concentrations of K+ by modulating the signal amplification effect of CPE. The LOD was determined to be ≈3.0 nm. This detection assay also showed high selectivity against other metal ions. This sensing scheme can be extended to the detection of a wide range of target materials by simply modifying the recognition aptamer sequence.

The ultrafast dynamics of Förster resonance energy transfer (FRET) and photo-induced charge transfer (PCT) has been investigated in an electrostatic complex of a fluorescein-labeled single-stranded DNA (as a FRET acceptor) and a cationic polyfluorene copolymer (as a FRET donor). The donor-acceptor intermolecular distance and total energy transfer efficiency are determined for a polymer/DNA complex with two different counter-ions and compared with those obtained using a theoretical model by considering the competition between FRET and PCT processes. The maximum total energy transfer efficiency (0.47) was estimated at the optimum donor-acceptor intermolecular distance of 39.6 A.

The dynamics of carriers in GaN epilayers is investigated using femtosecond pump-probe spectroscopy. After the residual chirp on the continuum probe is removed, the normalized difference spectra (NDS) for different probe energies are synchronized, recovering the full time resolution of our laser pulse. Our Monte-Carlo simulation agrees well with the unchirped NDS spectrum, which shows the development of the carrier distribution at early times, where phonon satellites are seen, together with a strong non-thermal electron distribution in the region of the LO-phonon energy arising from the remarkably strong electron-LO phonon interaction. Employing a new technique which involves the integration of the normalized NDS multiplied by the corresponding energy, a measure of the mean energy of the carriers in non-thermal states is obtained. By comparing the time-dependent energy loss with the theoretical energy loss rate, we estimate the effective temperature of the phonon modes as well as the population of phonons. © 2005 Elsevier B.V. All rights reserved.

Polarization modulation in CdSe quantum dots is presented in the framework of the optically-induced nonlinearities of spin dichroism. The real and the imaginary parts of the phase retardation, which are induced from the nonlinear refractive index of the spin-degenerate fine states, are shown spectrally. The polarization modulation is also described in terms of the Jones vector, where the spectral dependences of the amplitude and phase are shown. The optically-induced elliptical polarization of a Gaussian pulse in a feasible condition of multi-quantum dot-layers is predicted precisely in terms of the rotational and the elliptical angles for increasing pulse area up to π, which is also mapped on a the normalized Poincare sphere.

The ultrafast spin dynamics of the bright exciton in CdSe/ZnS nanocrystal quantum dots has been investigated using a circularly polarized pump-probe experiment. A remarkably fast spin flip (-500 fs) of the bright exciton was observed at 4 K, which is attributed to the anisotropic electron-hole exchange interaction and the random positioning of nanocrystal quantum dots. In the presence of an applied magnetic field (5 T), the exciton spin parallel to the external magnetic field was favored due to Zeeman splitting. We found that this imbalance can possibly be suppressed by the state-blocking and the mixing of the 1(L) and 1(U) states in asymmetric quantum dots.

International audience; The Aharonov-Bohm effect in ring structures in the presence of electronic correlation and disorder is an open issue. We report novel oscillations of a strongly correlated exciton pair, similar to a Wigner molecule, in a single nanoquantum ring, where the emission energy changes abruptly at the transition magnetic field with a fractional oscillation period compared to that of the exciton, a so-called fractional optical Aharonov-Bohm oscillation. We have also observed modulated optical Aharonov-Bohm oscillations of an electron–hole pair and an anticrossing of the photoluminescence spectrum at the transition magnetic field, which are associated with disorder effects such as localization, built-in electric field, and impurities.

Ultrafast non-equilibrium carrier dynamics and many body effects have been investigated in GaN beyond the Mott density. The transient (∼1 ps) induced absorption was observed near the band edge due to band gap renormalisation; collision broadening and temporal evolution of the mean carrier energy were also obtained experimentally. The development of the longitudinal optical (LO)-phonon induced non-thermal electron distribution observed in the pump-probe at early times (≤1 ps) was in excellent agreement with a Monte-Carlo simulation, where the mean carrier energy loss rate of screened carrier-phonon interactions was found to be further reduced due to the hot phonon effect. Schematic diagram of non-equilibrium carrier dynamics.

Interferometric correlation spectroscopy is performed to investigate the decoherence dynamics of localized excited states in a single GaAs/AlGaAs quantum ring. For increasing temperature and excitation, we observe that the decay of interferometric envelope and the Fourier-transformed spectrum remain exponential and Lorentzian, respectively. The linewidth broadening for temperature and excitation intensity can be attributed to enhanced acoustic phonon scattering and Auger scattering in the fast modulation limit through the barrier traps, where carriers are captured and escape randomly. Additionally, we suggest an internal scattering between the different vertical confinement states for the significantly short coherence time (

We report all-optical polarization switching based on resonant excitation of spin-polarized e-h pairs in CdSe nanocrystal quantum dots at room temperature. Pump-probe experiments have been performed using the same and the opposite configurations of circular polarizations. Comparing the co- and the cross-circular polarization cases, it is quite evident that selectively-excited spins are flipped to a balanced state within 1 ps and that during this time, the two spin states are equally populated. The all-optical switching results are found to be in close agreement with pump-probe experimental results. The optical switching technique proposed in the present investigation should be extremely useful for future ultrafast terabit communication systems.

The optical modal gain spectrum for a ZnO thin film was measured by using a variable stripe length method. Using the dierential equation for amplified spontaneous emission in a stripe geometry, we obtained stripe-length-dependent gain spectra, which enabled us to investigate the gain saturation in long stripe lengths. When the stripe was shorter than the saturation length, our analysis was in a good agreement with the gain obtained by commonly-used analysis [1]. For intermediate density ( nMott). Both gains saturate with increasing stripe length, but the electron-hole plasma becomes relatively dominant for long stripe lengths ( 1000 µm) while the exciton-exciton scattering is relatively suppressed. This result suggests that exciton-exciton scattering gain saturation is more vulnerable to increase in the stripe length increase since the excitonic stimulated emission occurs on a coherence scale of the localized area.

Radiative and non-radiative recombination processes of free excitons in GaN have been investigated in terms of exciton-polariton and bound exciton by using pump-probe technique. The initial non-radiative trapping process ( 40ps) of the resonantly-excited free excitons was attributed to generation of the bound excitons, in good agreement with the coupled rate equations in the four energy levels. As free excitons are released from the bound excitons due to thermal excitation, the activation energy for donor-bound exciton ( Eact = 16.3 ± 5.2 meV) was estimated by temperature-dependent photoluminescence measurements. A comparison of the reflectance spectrum at 4K with the exciton-polariton model enabled us to obtain the exciton-polariton dispersion with oscillator parameters such as resonance energy, polarizibility, and damping linewidth. The radiative recombination time of the activated free excitons ( 305ps) was observed to be comparable to the theoretical exciton-polariton decay time near the bottleneck regime ( 297ps), in which a significant group velocity reduction is seen.

The interfacial effect on thermal conductivity is studied with Y 2 O 3 thin films deposited on an Al 2 O 3 substrate. Y 2 O 3 thin films with the thickness between 100 and 500 nm are prepared using rf magnetron sputtering and thermal conductivity of the films is measured using the 3 ω method. The strong film thickness-dependent thermal conductivity due to the interfacial thermal resistance is observed. The film thickness-dependent thermal conductivity is explained by an interface thermal resistance between the film and substrate.

Optical gain measurements with femtosecond excitation were performed in CdSe colloidal quantum dots (QDs) dissolved in toluene using the variable stripe length method. Instead of ZnS-shell overcoating, we found that the spectral narrowing and intensity enhancement of the fluorescence can be achieved alternatively by excluding octadecene (ODE) at the preparation of QDs. The maximum gain (∼1.5 mm−1) in the ODE-excluded CdSe QDs is comparable to that of CdSe/ZnS core–shell structures. Despite the uniform size distribution ( σ = 0.25 nm ), a broad gain spectrum appears in both cases due to the recombination of many excited levels between biexciton and exciton states. The remaining surface states in the ODE-excluded CdSe QDs also contribute to gain (1.0 mm−1), which is involved with a three-level process.

We analyzed time-resolved and magneto-micro-PL of a single droplet quantum dot in terms of polarization anisotropy, decay time, and diamagnetic coefficient in order to support the presence of localized state in a large droplet quantum dot.

We have investigated that organic solvent (DMSO, dimethyl sulfoxide) modifies energy transfer efficiency between conjugated polymers (donors) and fluorescein-labeled single stranded DNAs (acceptors). In a mixture of buffer and organic solvent, fluorescence of the acceptors is significantly enhanced compared to that of pure water solution. This result can be attributed to change of the donor-acceptor environment such as decreased hydrophobicity of polymers, screening effect of organic solvent molecules, resulting in an enhanced energy transfer efficiency. Time-resolved fluorescence decay of the donors and the acceptors was modelled by considering the competition between the energy harvesting Foerster resonance energy transfer and the energy-wasting quenching. This enables to quantity that the Foerster distance (R 0 = 43.3 A) and resonance energy transfer efficiency (E FRET = 58.7 %) of pure buffer solution become R 0 = 38.6 A and E FRET = 48.0 % when 80% DMSO/buffer mixture is added.

A novel multi-functional dual-layer polymer electrolyte was prepared by impregnating the interconnected pores with an ethylene carbonate (EC)/dimethyl carbonate (DMC)/lithium hexafluorophosphate (LiPF6) solution. An incompatible layer is based on a microporous polyethylene (PE) and a compatible layer, based on a poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) is sub-microporous and compatible with an electrolyte solution. The Li electrode/the dual-layer polymer electrolyte/Li[Ni0.15Li0.23Mn0.62]O2 cell showed stable cycle performance under prolonged cycle number. This behavior is due to the enhanced compatibility between the matrix polymer and the liquid electrolytes within the submicroporous compatible layer, which could lead to a controlled Li+ deposition on the Li anode surface by forming homegeneous electrolyte zone near the anode.