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Optical temperature sensing based on luminescence intensity ratio shows significant potential in achieving accurate temperature detection. In this work, Sb3+/Mn2+ co-doped Cs 2 NaYCl 6 double perovskites were synthesised via a hydrothermal method. Introducing Sb3+ ions to the host significantly enhances the radiative recombination of self-trapped excitons (STEs), resulting in a broad blue emission. The co-doping of Mn2+ ions to the composition leads to a tunable dual-emission in the spectra, originating from the energy transfer between the STEs and Mn2+ ions. The dependence of the dual-emission on temperature is employed for optical temperature sensing. The maximum relative sensitivity, optimal thermal resolution, and optimal thermal repeatability are determined as 1.40 % K−1, 0.002 K and 99.3% at 250 K, respectively. The results indicate that the synthesised Cs 2 NaYCl 6 : Sb3+/Mn2+ double perovskites are promising candidates for high-sensitivity optical thermometers. [ABSTRACT FROM AUTHOR]

Multi-color fluorescent anti-counterfeiting technology possesses a wide range of application prospects. However, there is still a challenge on the development of new single-component multi-color fluorescent materials related to the excitation wavelength. Herein, we report an efficient multi-peak luminescent material, Sb3+, Mn2+ co-doped CsCdCl 3 , which emission with a long afterglow is related to the excitation wavelength. There are two independent energy transfer channels of Mn2+ under short- and long-wave excitation. Under 357 nm excitation, dual-emission is observed at 506 and 590 nm attributed to the 3P 1 –1S 0 and 4T 1 -6A 1 transitions of [SbCl 6 ]3- and Mn2+ ions, respectively. Under 254 nm excitation, the microcrystals have orange emission. Excitation wavelength-dependent and tunable dual-emission associated with the host self-captured excitons and [SbCl 6 ]3- to Mn2+ energy transfer. The microcrystal's afterglow time at room temperature is 3500 s, which is attributed to the modulation of the trap for Mn2+. These results indicate that the material has potential applications in the field of multicolor fluorescent anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Lead-free metal halide double perovskites with non-toxicity and stable self-trapped excitons (STEs) have received considerable attention in the field of photoelectric applications. However, it is difficult to achieve independent control of its photoluminescence performance to meet the requirements of multi-band emission. Herein, a doping strategy was employed to introduce lanthanide ions (Ln3+) into Cs 2 NaInCl 6 :Sb3+ nanocrystals (NCs), enabling the multicolor emission modulation ranging from blue to red and even white light. Benefiting from the efficient energy transfer from Sb-related self-trapped excitons to Ln3+ ions, green and red emissions originate from the 5D 0 →7F J (J = 1, 2, 3, 4) transition of Eu3+ ions and 5D 4 -7F J (J = 6, 5, 4, 3) transition of Tb3+ ions, respectively. According to the tunable polychromatic photoluminescence characteristics of doped NCs, the dual-mode fluorescent anti-counterfeiting applications were exhibited. Furthermore, the distinct temperature sensitivities exhibited by blue (453 nm) and red (617 nm) emission in Cs 2 NaInCl 6 :Sb3+/Eu3+ NCs provide the opportunity for the optical thermometry, which demonstrates the maximum absolute and relative sensitivity are 0.0018 and 0.43 % K−1, respectively. These results indicate that the synthesized codoped NCs have the potential applications in multifunctional fields, such as optical thermometer, fluorescence anti-counterfeiting, and multicolor-LEDs. • The co-doping of Eu3+ and Tb3+ ions enables Cs 2 NaInCl 6 :Sb3+ NCs to achieve a tunable multicolor emission within a wide visible spectrum range from blue to green and red. • Dual-mode fluorescent anti-counterfeiting applications were exhibited using Cs 2 NaInCl 6 :Sb3+, Ln3+ NCs. • Optical thermometry was achieved based on Cs 2 NaInCl 6 :Sb3+, Eu3+ NCs and the maximum absolute and relative sensitivity were 0.0018 K−1 and 0.43 %K−1. [ABSTRACT FROM AUTHOR]

Zero-dimensional organic-inorganic hybrid metal halides that can realize single-component white emission have attracted extensive attention due to the high-quality requirements of solid-state lighting technology. Although efficient white emission can be obtained in metal halides, the realization of tunable emission and high color rendering index of single-component white light remains a challenge. Herein, we report the binary halide (TEA) 2 (MnCl 4) 1- x (SbCl 5) x (TEA+ = tetraethylammonium, C 8 H 20 N+), realizing warm white emission with a photoluminescence quantum yield of 86.24 %. (TEA) 2 (MnCl 4) 1- x (SbCl 5) x halides with multiple optical polyhedral units ([SbCl 5 ]2- pyramid and [MnCl 4 ]2- tetrahedron) shows triple-peaked emission at 460 nm (free excitons emission), 520 nm (d – d transitions of Mn2+ ions), and 630 nm (self-trapped excitons emission). Interestingly, (TEA) 2 (MnCl 4) 1- x (SbCl 5) x halides exhibit emission color tunability by changing excitation energy and temperature, respectively. A comparison of lifetime spectra, as well as the temperature-variation spectra, was utilized to elucidate the energy transfer mechanism between Sb3+ and Mn2+ ions. The single-component white light-emitting diode fabricated by (TEA) 2 (MnCl 4) 0.92 (SbCl 5) 0.08 sample exhibits a high color rendering index of 92. This approach involving multiple emission mechanisms from different polyhedrons represents a promising avenue for designing single-component white-light emitters. • (TEA) 2 (MnCl 4) 1- x (SbCl 5) x halides showed high-performance white light emission (PLQY∼86.24 %). • The relationship between the host and guest has been established. • The unique energy transfer occurs from Sb3+ ions to Mn2+ ions has been confirmed. • High-efficiency luminescence (CRI∼92, CCT∼4253 K) of the fabricated WLED can be applied in the lighting field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bi-bridge BiPO 4 /CdS heterojunction (BiPO 4 /Bi/CdS) with oxygen vacancy was fabricated. • BiPO 4 /Bi/CdS displayed high intersystem crossing efficiency. • The effective intersystem crossing from singlet to triplet excitons facilitated 1O 2 production. • BiPO 4 /Bi/CdS exhibits excellent photocatalytic activity in ofloxacin degradation. • Mechanism of type-II heterojunction based on exciton energy transfer was first set forth. The separation of photogenerated charge carriers has been widely investigated, but exciton effects in type-II heterojunctions are often overlooked. Herein, the Bi-bridge BiPO 4 /CdS type-II heterojunction (BiPO 4 /Bi/CdS) with oxygen vacancy was successfully fabricated. BiPO 4 /Bi/CdS displayed stronger phosphorescence emission than BiPO 4 /Bi, suggesting the higher efficiency of intersystem crossing. The effective intersystem crossing from singlet to triplet excitons facilitated the activation of O 2 to singlet oxygen (1O 2), which was the product of energy transfer from the triplet excitons to the ground-state O 2 molecule. The synergies between oxygen vacancy, surface plasmon resonance of Bi and heterojunction-construction promoted charge carrier separation and the generation of 1O 2. As a result, BiPO 4 /Bi/CdS exhibited excellent photocatalytic activity in ofloxacin degradation with 93% degradation efficiency and 55% mineralization efficiency under the joint action of 1O 2 and h+ as reactive species. More importantly, the mechanism of BiPO 4 /Bi/CdS type-II heterojunction was set forth from the coupling of charge carriers and exciton effects. This work sheds new light on the regulation of excitonic effects in type-II heterojunction and provides unique insight into 1O 2 production. [ABSTRACT FROM AUTHOR]

• A series of Mn-doped A 2 PbBr 4 2D perovskites are synthesized and the luminescence properties of Mn2+ ions in related to the A-site cations is explored. • The highest efficiency of the energy transfer from excitons to Mn2+ reaches as high as 78.08 % in (PPA) 2 PbBr 4 :60 % Mn2+ 2D perovskite. • The luminescence mechanism of Mn-doped (PPA) 2 PbBr 4 perovskite with different Mn2+ concentrations are investigated by temperature dependent PL spectra. The incorporation of Mn2+ ions has been widely used to modulate optical properties of two-dimensional (2D) organic-inorganic hybrid perovskites (OIHPs). However, the luminescence mechanism of Mn2+ ions that is related to the A-site cations remains largely unexplored. Herein, we report the synthesis of a series of Mn-doped A 2 PbBr 4 (A = C 6 H 5 (CH 2) n NH 3 , n = 1,2,3,4,) 2D perovskites. The (C 6 H 5 (CH 2) 3 NH 3) 2 PbBr 4 ((PPA) 2 PbBr 4) 2D perovskite exhibited a maximum photoluminescence (PL) quantum yield of 67 %, a prolonged PL lifetime of 0.75 ms, and the highest energy transfer efficiency of 78.07 %. Furthermore, we systematically investigated the luminescence properties of Mn-doped (PPA) 2 PbBr 4 perovskite with different Mn2+ concentrations. The temperature dependent PL spectra indicate a thermalized de-trap process of self-trapped exciton at high temperatures and the presence of permanently shallow defect states in highly doped samples with lower activation energy. We reported the luminescence properties of Mn-doped 2D organic-inorganic hybrid perovskites, with a particular focus on the (PPA) 2 PbBr 4 perovskite material. [Display omitted] [ABSTRACT FROM AUTHOR]

Ce+3 doped CsLaSiS 4 single crystals were synthesized using high-temperature flux synthesis. XRD analysis showed that the products are isostructural to CsLaSiS 4 and crystallize in orthorhombic space group Pnma. Absorption spectra were studied at room temperature, and photoluminescence properties were examined in the temperature range of 5–310 K. The energy of interband transitions E g = 3.75 eV was determined at room temperature in the Tauc model. At room temperature, only a non-elementary d → f emission band of Ce+3 ions was observed in the 520 nm region. The luminescence kinetics upon excitation by a pulsed cathode beam or X-ray synchrotron radiation exhibited a dominant nanosecond component. Decay time, as well as build-up time, decreased with increasing concentration of Ce+3 ions. Concentration quenching of Ce+3 emission was not observed up to 11.9 mol% of Ce+3 ions. At a low temperature of 5 K, new wide emission bands at 422 and 688 nm appeared in the photoluminescence spectrum. It is shown that the 422 nm band in the photoluminescence spectrum corresponds to host emission, specifically the luminescence of self-trapped excitons (STE). The 688 nm emission band corresponds to defect-related luminescence. STE emission is quenched according to the Mott law at temperatures above 26 K with an activation energy of 20 meV. An efficient energy transfer channel from the STE to the Ce+3 ion via the radiative resonance mechanism is observed. The emission of Ce+3 ions and defect-related luminescence can be excited by the intracenter way, due to electron-hole recombination, or by the creation of defect bound excitons. Based on the obtained spectroscopic data, a band scheme illustrating the processes of relaxation of electronic excitations at T = 5 K in Ce+3 doped CsLaSiS 4 crystals is proposed. [Display omitted] • Ce+3 doped CsLaSiS 4 single crystals were obtained through high-temperature flux synthesis. • Inter configurational d-f transitions in Ce3+ ions were studied upon both UV- and X-ray excitation. • Luminescence kinetic studies were conducted using a pulsed cathode beam and X-ray synchrotron radiation. • Self-trapped excitons, defect-bound excitons, and impurity luminescence were observed at T = 5 K. [ABSTRACT FROM AUTHOR]

Lead-free double perovskites have superb luminescence properties for broad applications. However, increasing or improving near-infrared (NIR) photoluminescence (PL) is still a challenge. In this paper, a high-performance microcrystal is designed based on Tm3+ heavily doped Cs 2 Ag 0.6 Na 0.4 In 0.9 Bi 0.1 Cl 6 (CANIBC), which realize both the self-trapped excitons (STEs) and Tm3+ NIR emission. The emission mechanism and energy transfer (ET) process are studied by steady-state and time-resolved PL spectra. The ET efficiency from STEs to Tm3+ can reach 38.3 %, and the NIR PL quantum yield of Tm3+ can reach 22.7 %. Meanwhile, the PL spectra of Tm3+-doped CANIBC microcrystals (MCs) with different concentrations are used to investigate their temperature sensing properties based on both fluorescence intensity ratio (FIR) and lifetime. Based on the FIR, relative sensitivity (S r) can reach 2.93 % K−1 at 303 K. Moreover, based on lifetimes, S r can maintain more than 1.55 % K−1 from 303 to 453 K, and maximum S r can also achieve 2.38 % K−1 at 360 K. These excellent luminescence and sensing properties offer greater development potential in the field of NIR phosphor and thermometry. • As-synthesized materials present both perovskite and Tm3+ emission. • Energy transfer efficiency is obtained from the peak decompositions. • Near-infrared photoluminescence quantum yield of Tm3+ can reach 22.7 %. • Sensitivity of fluorescence intensity ratio reaches 2.93 % K−1 at 303 K. • Sensitivity of lifetime sensing sustains beyond 1.55 % K−1 from 303 to 453 K. [ABSTRACT FROM AUTHOR]

• Both energy transfer and charge transfer processes were observed. • A method for evaluating the contribution of energy transfer was developed. • Energy level offsets affect charge photogeneration processes. All-small-molecule organic solar cells (ASM OSCs) hold great promise in OSCs owing to their defined structures, simple purification, and good reproducibility, but are challenging for further improved efficiency. The energy level strategy has been broadly applied to obtain a better performance; however, a comprehensive understanding of the effects of energy level offset on photoexcitation dynamics in ASM OSCs is rarely studied. Herein, for Y-series molecules (Y6, Y10, Y5, and BTP-4F-12) based ASM OSCs, the effect of energy level offset on charge photogeneration was investigated using steady-state and time-resolved spectroscopies. We found that both energy and charge transfer could occur in blend films. A method to quantitatively analyze the contribution of charge and energy transfer processes was developed. For BTR-Cl:Y6 with the highest LUMO level offset, ∼ 23% of photogenerated excitons in donor dissociated via "energy transfer and the subsequent charge transfer" pathway, suggesting that the energy transfer in blend films should also be considered. And for the hole transfer, the excitons in Y-series molecules can only be effectively dissociated when the HOMO energy level offset is higher than 0.11 eV. Besides, a higher energy level offset would also suppress carrier recombination in ultrafast timescale. These results may shed light on the design of ASM OSCs. [ABSTRACT FROM AUTHOR]

In this study, we fabricated Cs 3 ScCl 6 crystals doped with different concentrations of Ce and investigated their luminescence properties. In both the photoluminescence (PL) and scintillation spectra, emission bands attributable to Ce3+ 5d–4f transition were observed. The PL temporal profiles revealed decay time constants of ~35 ns, which are typical values for Ce3+ 5d–4f transition. In the scintillation temporal profiles, two decay components were observed. The fast and slow components could be attributed to Ce3+ 5d–4f luminescence and self-trapped excitons (STEs) or a slow energy transfer from STEs to Ce3+, respectively. The maximum light yield was 9200 photons/MeV for a Ce concentration of 0.5 mol%. [ABSTRACT FROM AUTHOR]

The paper contains detailed crystal structure and photoluminescence studies of the Bi3+ and Bi3+-Eu3+ co-doped Gd 3 Ga 5 O 12 (GGG) garnet. The studied materials have been synthesized in the form of microcrystalline powders by the common solid-state reaction method. Precise crystal structure parameters were derived from the X-ray powder diffraction data. Photoluminescence studies were done by the steady-state and time-resolved techniques in the 4.2–400 K temperature range. The studied materials show no UV luminescence caused by electronic transitions of a Bi3+ ion. The observed luminescence in visible is interpreted by excitons localized around Bi3+ ions. In particular, two emission bands located at 2.55 eV (486 nm) and 2.05 eV (605 nm) at 4.2 K were revealed. The main emission band at 2.55 eV is attributed to the triplet relaxed state of excitons localized around single (regular) Bi3+ ions, whereas the weaker band at 2.05 eV is related to some associates of a single Bi3+ ion with a crystal lattice defect. The performed studies for Bi3+-Eu3+ co-doped samples indicate that the energy transfer from Bi3+ to Eu3+ is radiative and is caused by reabsorption of the Bi-related exciton emission by Eu3+ ions. The studied materials were also characterized as a single-phase converting phosphor for near-UV excited white LEDs. The possibility of the emission color tuning from blue to orange-red at UV excitation by the way of changing of Bi3+ and Eu3+ concentrations was shown. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report a theoretical investigation on the excitation of surface plexciton wave at interface of a metal and a columnar thin film infiltrated with J-aggregate dyes using the transfer matrix method in Kretschmann configuration. There exist the regimes of the plasmon–exciton interaction including the weak to strong coupling by tuning structural parameters. We find Rabi splitting energies between 204–378 meV corresponding to the time period 11–20 fs which includes to the fast energy transfer from surface plasmon polaritons to excitons. The phase speed and propagation length of surface plexcitonic waves were in the range of 0.4 to 0.9c and 0.4 to 6 μ m. The results of the time-averaged Poynting vector of surface plexciton waves refer to the localization of them at interface of plasmonic and excitonic mediums. [ABSTRACT FROM AUTHOR]

Abstract Two-dimensional electronic spectroscopy has become one of the main experimental tools for analyzing the dynamics of excitonic energy transfer in large molecular complexes. Simplified theoretical models are usually employed to extract model parameters from the experimental spectral data. Here we show that computationally expensive but exact theoretical methods encoded into a neural network can be used to extract model parameters and infer structural information such as dipole orientation from two dimensional electronic spectra (2DES) or reversely, to produce 2DES from model parameters. We propose to use machine learning as a tool to predict unknown parameters in the models underlying recorded spectra and as a way to encode computationally expensive numerical methods into efficient prediction tools. We showcase the use of a trained neural network to efficiently compute disordered averaged spectra and demonstrate that disorder averaging has non-trivial effects for polarization controlled 2DES. [ABSTRACT FROM AUTHOR]

Abstract The A′ luminescence band due to the In+ center in co-doped NaCl:I−,In+ crystals is observed even under excitation at the absorption band due to the I− center, indicating the energy transfer processes from the I− center to the In+ center. The temporal profile of the exciton luminescence bound to the I− center in the co-doped NaCl:I−,In+ crystals exhibits the faster decay than that of the bound exciton luminescence in single-doped NaCl:I− crystals. The reduction of the decay profile is observed even in the samples with an average distance of about 20 nm between two kinds of the impurity centers. The average distance is significantly larger than the critical distance of 3.0 nm for resonance energy transfer, which is estimated from the overlap between the bound exciton luminescence band and the C absorption band due to the In+ center. The facts indicate that the energy transfer process is not resonant-type and/or through reabsorption of the luminescence. We discuss the energy transfer mechanism from the I− to In+ centers in the NaCl:I−,In+ crystals. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract We analyze the exciton dynamics in Photosystem I from Thermosynechococcus elongatus using the distributed memory implementation of the hierarchical equation of motion (DM-HEOM) for the 96 Chlorophylls in the monomeric unit. The exciton-system parameters are taken from a first principles calculation. A comparison of the exact results with Förster rates and Markovian approximations allows one to validate the exciton transfer times within the complex and to identify deviations from approximative theories. We show the optical absorption, linear, and circular dichroism spectra obtained with DM-HEOM and compare them to experimental results. [ABSTRACT FROM AUTHOR]

Abstract We demonstrate high-efficiency warm white organic light-emitting diodes (WOLEDs) with an interface-exciplex-forming structure of hole-transporting 1,3-Bis(carbazol-9-yl)benzene (mCP) as electron-donor and electron-transporting 4,6-Bis(3,5-di(pyridin-3-yl)phenyl)-2-(pyridin-3-yl)pyrimidine (B3PyMPM) as electron-acceptor. The exciplex can be formed effectively at the interface of mCP/B3PyMPM due to the excellent charge-transporting properties of mCP and B3PyMPM and the large energy-levels offset of mCP/B3PyMPM interface, and then its energy transfers to the low-lying triplet states of the blue TADF fluorophors or yellow phosphors. As a result, a maximum power efficiency (PE) of 79.2 lm/W and maximum external quantum efficiency (EQE) of 22.3% were achieved from the warm WOLED. The key factor for such high efficiency WOLED is believed to be from the effective harvest of triplet excitons of the interface-exciplex via reverse intersystem crossing process (RISC). Graphical abstract Image 1 Highlights • Efficient triplet harvesting from the interface-exciplex formed at the interface of mCP/B3PyMPM is investigated. • High efficiency interface-exciplex warm WOLED with a maximum PE of 79.2 lm/W (EQE max : 22.3%.) is achieved. • The WOLED achieved PE of 34.0 lm/W (EQE: 13.8%) at 1000 cd/m2, corresponding to a CIE coordinate of (0.451, 0.506). [ABSTRACT FROM AUTHOR]

We model the energy transfer dynamics in the Lhca4 peripheral antenna of photosystem I from higher plants. Equilibration between the bulk exciton levels of the antenna and the red-shifted charge-transfer (CT) states is described using the numerically inexpensive Redfield-Förster approach and exact hierarchical equation (HEOM) method. We propose a compartmentalization scheme allowing a quantitatively correct description of the dynamics with the Redfield-Förster theory, including the exciton-type relaxation within strongly coupled compartments and hopping-type migration between them. The Redfield-Förster method gives the kinetics close to the HEOM solution when treating the CT state as dynamically localized. We also demonstrate that the excited states strongly coupled with the CT should be considered as localized as well. [ABSTRACT FROM AUTHOR]

An effective approach to realize high-efficiency exciplex-based organic light-emitting diodes (OLEDs) is proposed by employing long-range coupling between electron-hole pairs and efficient energy transfer. The space-separated holes and electrons form exciplexes through charge-transfer states, and devices with such structures can reduce exciton quenching in a certain extent compared to those based on interfacial exciplexes. Remarkable external quantum efficiency about 12.6% is achieved by introducing a yellow exciplex system in a donor/spacer/acceptor structure because of the suppression of exciton quenching and the efficient energy transfer. Such a unique strategy is beneficial to better utilizing the triplet excitons and thus achieving high performance exciplex-based OLEDs. [Display omitted] • Efficient non-doped yellow OLED with a D/S/A structure and energy transfer. • The unique structure can alleviate the exciton quenching and effectively promote the exciton utilization. • A new method of constructing full exciplex emission white OLEDs is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescence Resonance Energy Transfer from P3HT to CuInSe 2. • Analytical study of the absorption and emission spectra of P3HT:CuInSe 2 composites. • Förster distance of critical energy transfer is estimated as 3.61 nm. • The average distance between donor–acceptor is found to be 4.71 nm. • Analysis of resonance charge transfer by estimation of HOMO-LUMO energy of donor–acceptor. This letter reports the paramount fluorescence resonance energy transfer mechanism for photo induced charge transfer from P3HT to solvothermally derived CuInSe 2. The HOMO (-4.85 eV) and LUMO (-3.38 eV) energy states of CuInSe 2 (electrical conductivity = 1.1x 10-7 Scm−1) are determined from cyclic voltammetry and optical study. This HOMO-LUMO position agrees to select P3HT polymer as possible donor of excitons. Steady-state luminescence study of composite (P3HT:CuInSe 2) demonstrates possibility of successful charge transfer. Stern–Volmer analysis of absorption and emission spectroscopy ensures static energy quenching phenomena. The Förster distance (R 0) of critical energy transfer is estimated as 3.61 nm. The average distance between donor–acceptor (r avg = 4.71 nm) is<8 nm and within the range 0.5R 0 < r < 1.5R 0 (1.81 nm < r < 5.42 nm), which ensures energy transfer from P3HT to CuInSe 2. [ABSTRACT FROM AUTHOR]

Exciplex host in organic light-emitting diodes (OLEDs) can use radiative energy of upconverted singlet excitons by reverse intersystem crossing and thus transfer the energy to guest emission to effectively enhance the device performance. However, investigation of OLED with pure blue emission using exciplex host has rarely been reported. In this contribution, solution-processed OLEDs using exciplex host with pure blue fluorescence-type guest emission have been achieved. Through optimization of guest concentration, improved efficiency and blue-shifted electroluminescence spectrum of the OLED device was obtained. This study provides a method to fabricate efficient OLEDs with deeper blue emission for application in full-color display and white lighting source with high color rendering index. [ABSTRACT FROM AUTHOR]

We have constructed an assistant dopant system in red phosphorescent OLEDs. In the system, we chose the 4,4′-Bis(carbazol-9-yl)biphenyl (CBP) as the host material, a thermally activated delayed fluorescence (TADF) 4CzIPN as the assistant dopant and a red phosphor Hex-Ir(phq) 2 (acac) as the guest. The assistant dopant system can remarkably reduce the turn-on voltage and increase device brightness. Meanwhile, devices with assist dopant system show negligible efficiency roll-off even in high luminance and current density. The current efficiency of optimized device with 15 wt% 4CzIPN only drops to 12.7 cd/A at 74,532 cd/m 2 from maximum 13.7 cd/A. By further investigation on the exciton generation mechanism and the energy transfer process in the system, the main cause of the improvement has been unveiled. [ABSTRACT FROM AUTHOR]

High efficiency non-doped white organic light-emitting diodes (WOLEDs) have been realized by inserting an ultrathin yellow fluorescent emitter into a bilayer blue exciplex system. The white emission comes from the incomplete energy transfer from the blue exciplex to the yellow fluorescent emitter. By tuning the location of the ultrathin fluorescent emitter layer in the device, excitons directly formed in the yellow fluorophore can be neglected and the Dexter energy transfer from triplet state of exciplex to yellow fluorophore is also suppressed, contributing to the high efficiency. The WOLED achieves a maximum current efficiency of 27.2 cd/A, with Commission Internationale de I'Eclairage (CIE) coordinates of (0.35 ± 0.02, 0.38 ± 0.02). [ABSTRACT FROM AUTHOR]

A novel and simple photoelectrochemical (PEC) biosensing method for microRNA-21 (miRNA-21) detection is reported based on energy transfer (ET) between CdS:Mn doped structure (CdS:Mn) and Au nanoparticles (AuNPs). In this protocol, TiO 2 -CdS:Mn hybrid structure was used as a sensing platform for hairpin DNA immobilization. In the absence of miRNA-21, the immobilized DNA was in the hairpin form. In this state, the photocurrent of the electrode was greatly depressed, due to the effective ET effect produced by short interparticle distance between CdS:Mn and AuNPs. In the presence of miRNA-21, the hairpin DNA hybridized with miRNA-21 and changed into a more rigid, rodlike double helix, which forced the AuNPs away from the electrode surface, leading to obvious recover of photocurrent because of the vanished damping effect. Integrating the fine PEC performance of TiO 2 -CdS:Mn hybrid structure with the significant ET effect between CdS:Mn and AuNPs, the sensitive detection of miRNA-21 was realized in a linear range of 1.0 fM to 10.0 pM with a low detection limit of 0.5 fM. This method might be aussichtsreich for the detection of miRNAs and other biomarkers. [ABSTRACT FROM AUTHOR]

A novel triplet exciton guiding mixed host managing triplet exciton-polaron annihilation by separating the triplet excitons and polarons in the different host was developed. A high triplet energy/narrow gap host and a low triplet energy/wide gap host were mixed to isolate the triplet excitons and polarons, which could improve the extrapolated lifetime of the phosphorescent organic light emitting diodes by more than twice. The triplet exciton-polaron annihilation reducing mechanism was confirmed by triplet energy transfer, single carrier device test and triplet exciton-polaron annihilation rate constant study of the singlet host and mixed host. [ABSTRACT FROM AUTHOR]

We investigated quantized-charge and energy transfer at the pentacene/lead sulfide (PbS) interface through realization of PbS nanocrystal (NC) size-dependent quantum confinement effect, providing insights into the presence of triplet exciton dissociation and energy transfer. With PbS nanocrystals (NCs) of a small size (∼3 nm), quantized charge and energy transfer at the pentacene/PbS NC interface leads to a large photocurrent while PbS NCs of a large size (∼7 nm) causes a far reduced photocurrent. Through comparison between the normal and inverted structures, importantly, exciton dissociation and energy transfer are turned out to be sensitive to subtle structural change at the interface. [ABSTRACT FROM AUTHOR]

Photoluminescence characteristics of Gd 3 Ga 5 O 12 :Bi single crystalline films with different Bi contents grown by the liquid phase epitaxy are studied by the steady-state and time-resolved luminescence spectroscopy methods in the 4.2–500 K temperature range under excitation within the 3.8–6.0 eV. No ultraviolet emission, which could be ascribed to the radiative decay of the triplet excited state of Bi 3+ , is observed. Only visible emission is shown to arise from the Bi 3+ –related luminescence centers. Both the intense 2.54 eV emission and the weaker 2.46 eV emission of Gd 3 Ga 5 O 12 :Bi are shown to be of exciton origin. We suggest that they are due to the radiative decay of an exciton localized around a single Bi 3+ ion and a dimer {Bi 3+ –Bi 3+ } center, respectively. The characteristic parameters of the corresponding exciton states are determined. The photostimulated processes, resulting in the localized excitons formation under excitation in the Bi 3+ –related absorption bands, are discussed. Peculiarities of Gd 3+ –Bi 3+ energy transfer processes in Gd 3 Ga 5 O 12 :Bi are investigated. The possibility of application of Bi 3+ –doped gadolinium gallium garnets in scintillation detectors and light emitting diodes is considered. [ABSTRACT FROM AUTHOR]

Single-emitting-layer hybrid white organic light-emitting diodes (SEL-hybrid-WOLEDs) are promising candidates for large-area lightings, however, ideal hybrid WOLEDs with a simple structure and high-efficiency, low roll-off, high color rendering index (CRI) and superior CIE coordinates have been rarely reported. In this paper, high-performance SEL-hybrid-WOLEDs are demonstrated by utilizing a thermally activated delayed fluorescence (TADF) host emitter combined with green and red phosphors. The optimized WOLED exhibits an external quantum efficiency (EQE) of 20.2%, CIE coordinates of (0.360, 0.390) and a CRI of 85. Remarkably, an extremely low efficiency roll-off is also realized, with an EQE of 19.4% remained even at the practical luminance of 1000 cd/m 2 , resulting from the wide recombination zone as well as the well-tuned energy transfer in the emitting layer. Moreover, benefited from the stable recombination zone, superior color stability was also achieved. The intriguing results, we believe, greatly manifest the great potential of such a strategy and may pave the way towards real applications. [ABSTRACT FROM AUTHOR]

5-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (DBA-DI) with high triplet energy was utilized as efficient blue emission dopant to construct solution-processed thermally activated delayed fluorescence-phosphorescence (TADF-phosphorescence) hybrid white organic light-emitting diodes (WOLEDs). Meanwhile, a series of TADF-phosphorescence hybrid WOLEDs composed of bis(2-phenylquinoline) (2,2,6,6-tetramethylheptane-3,5-dionate)iridium(III) (PQ 2 Ir(dpm)), tris(2-(4-tolyl)-phenylpyridine)iridium (Ir(mppy) 3) and DBA-DI are successfully developed by introducing the co-host system consist of poly(N-vinylcarbazole) (PVK) and 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPy) with high color rendering index (CRI) and improving the utilization of triplet excitons. Furthermore, energy transfer processes among different emitters were investigated in detail based on absorbance spectra, photoluminescence and transient photoluminescence spectra. Ultimately, the Commission Internationale de I'Eclairage coordinates of the optimum solution-processed WOLEDs in warm-white emission region are (0.41, 0.41) and high CRI is 82. Furthermore, the same device realized outstanding efficiencies of 32.14 cd A−1, 21.00 lm W−1 and 15.1% at high brightness of 1000 cd m−2. Efficient solution-processed TADF-phosphorescence white organic light-emitting diodes with DBA-DI, Ir(mppy) 3 and PQ 2 Ir(dpm) as blue, green and red emitters based on PVK and 26DCzPPy as hosts were realized by improving the utilization of triplet excitons. [Display omitted] • Efficient solution-processed hybrid white electroluminescent devices with slow efficiency roll-off were designed and fabricated. • The co-host system is beneficial to film stability and balance carriers' distribution. • Accurate dopant concentrations of emitters and thicknesses of electron transport layer ensure the efficient energy transfer. • The introduction of blue TADF emitter greatly improved utilization probability of excitons and reduced manufacture cost. [ABSTRACT FROM AUTHOR]

We demonstrated highly efficient traditional orange emission fluorescent OLEDs with simple device structure by utilizing energy transfer from bilayer interface TADF exciplex to dopant. With rubrene as the dopant, under the optimized concentration of 1.5%, the device achieved maximum current efficiency, power efficiency and EQE of 25.3 cd/A, 22.6 lm/W and 8.1%, respectively. Even at the luminance of 1000 cd/m 2 , the EQE also remained 6.9%. The obtainment of so high efficiency could be attributed to highly efficient RISC efficiency of triplet excitons and energy transfer efficiency from TADF exciplex to dopant. The more detailed working mechanism was also argued. [ABSTRACT FROM AUTHOR]

In our previous letter (Kimura, 2016), we constructed time-dependent renormalized Redfield theory (TRRT) only for diagonal transition in a reduced density matrix. In this letter, we formulate the general expression for off-diagonal transition in the reduced density matrix. We discuss the applicability of TRRT by numerically comparing the dependencies on the energy gap of the exciton relaxation rate by using the TRRT and the modified Redfield theory (MRT). In particular, we roughly show that TRRT improves MRT for the detailed balance about the excitation energy transfer reaction. [ABSTRACT FROM AUTHOR]

A computational scheme to describe the coherent dynamics of excitation energy transfer (EET) in molecular systems is proposed on the basis of generalized master equations with memory kernels. This formalism takes into account those physical effects in electron-bath coupling system such as the spin symmetry of excitons, the inelastic electron tunneling and the quantum features of nuclear motions, thus providing a theoretical framework to perform an ab initio description of EET through molecular simulations for evaluating the spectral density and the temporal correlation function of electronic coupling. Some test calculations have then been carried out to investigate the dependence of exciton population dynamics on coherence memory, inelastic tunneling correlation time, magnitude of electronic coupling, quantum correction to temporal correlation function, reorganization energy and energy gap. [ABSTRACT FROM AUTHOR]

In this work about doped PHOLEDs, energy transfer between host and guest molecules were proved to play more important role in generating triplet exciton for guest material than the electron transfer in luminescent layer. [Display omitted] • A deep theoretical investigation on the charge and energy transfer processes between host and guest molecules in the phosphor-doped OLED were investigated. • Energy transfer between host and guest molecules plays more important role in generating triplet exciton for guest material than the charge transfer. • The energy transfer is less sensitive to the intermolecular relative position than the electron transfer. Phosphor doped OLEDs have been developed all the way in recent years due to their high and stable efficiency and more practical applications in various display devices. However, complicated electron and energy transfer between host and guest materials have not been clear to us so far, which brings about the difficulty in making favorable doping scheme to realize best performance. In order to present some issues for these processes, we carried out density functional theory (DFT) calculations and molecular dynamics (MD) simulation to describe the electron and energy transfer between host molecule CBP and guest molecules (ppy) 2 Ir(bppo) , (bppo) 2 Ir(ppy) and (bppo) 2 Ir(acac). The results show that the energy transfer from host to guest molecules is not only more significant than the charge transfer, but also exhibits less dependence on the relative orientation between host and guest molecules. It indicates the decisive contribution of energy transfer to the high-efficiency phosphorescence of guest molecules. At the same time, the much higher energy transfer rates between triplet excited states than those between singlet excited states indicates the importance of generating triplet-state excitons in host materials for phosphor doped OLEDs. Therefore, we hope this work could provide some theoretical guidance for further development of host–guest materials. [ABSTRACT FROM AUTHOR]

The exciton recombination zone and energy loss of organic light-emitting diodes (OLEDs) with thermally activated delayed fluorescence (TADF) emitter 4CzTPN (1, 2, 4, 5-Tetrakis(carbazol-9-yl)-3, 6-dicyanobenzene) as the dopant are explored by engineering hosts. The results demonstrate that the exciton recombination zone is determined by the matching condition between hole and electron mobility of hosts. The shift of the recombination zone from cathode to anode side induces a blue-shift of the electroluminescent spectra. And energy loss can be reduced by well-matched carrier mobility and TADF feature of host as well as lower energy level offset between host and guest. Specifically, the exciplex-co-hosted device delivers the maximum current/power efficiency/external quantum efficiency of 29.06 cd·A−1/28.89 lm·W−1/8.86%, respectively, enhanced by more than 50% than the single-component-hosted devices. This study illuminates that controlling exciton recombination zone and energy loss via engineering hosts is a feasible strategy for developing high performance TADF OLEDs. [ABSTRACT FROM AUTHOR]

Single-component phosphors with efficient and stable white-light emission are designed to overcome the trouble of various deteriorations and reabsorptions in the conventional mixing multiple-component phosphors for lighting applications. Here, Er3+ is introduced partially into the double perovskite Cs 2 Ag(Na)In(Bi)Cl 6 lattice to tune white-light emission through adjusting its content. The as-synthesized material itself possesses strong tunable white-light emission under irradiation by 405 nm light due to the combination of self-trapped excitons emission and efficient characteristic emission of Er3+. Steady-state photoluminescence (PL) and time-resolved PL spectra are measured to characterize luminescence properties and clarify the luminescence mechanism. The PL quantum yield of undoped Cs 2 Ag(Na)In(Bi)Cl 6 can achieve 64%. After doping 2 mmol Er3+, energy transfer efficiency from perovskite to Er3+ can reach 30.1%, with an improved PL quantum yield of 71%. The full-spectrum white-light emission can be realized by the Er3+ doped Cs 2 Ag(Na)In(Bi)Cl 6 phosphors-converted 410–420 nm light-emitting diode. Commission International de I'Eclairage (CIE) color coordinates of white light can be improved from (0.47, 0.41) to (0.33, 0.35) with the increase of Er3+ content, and the corresponding color temperature is tuned from 2532 to 5760 K. These characteristics demonstrate that Er3+ doped Cs 2 Ag(Na)In(Bi)Cl 6 phosphors are promising single-component white-light phosphors for next-generation lighting. [Display omitted] • The as-synthesized materials possess both perovskite and Er3+ emission. • Energy transfer from perovskite to Er3+ leads to Er3+ emission. • Energy transfer efficiency from self-trapped excitons to Er3+ can reach 30.1%. • Commission International de I'Eclairage (CIE) can be improved to (0.33, 0.35). [ABSTRACT FROM AUTHOR]

In this study, we reported the plasmon-exciton coupling for excitation of the surface plexciton wave in columnar thin film with a central exciton slab using the transfer matrix method in Turbadar–Kretschmann–Raether configuration. The optical absorptance spectra for surface plasmon polariton, surface exciton and surface plexciton was investigated at different structural parameters in proposed structure. The characteristics of surface optical modes were analyzed and there was an anticrossing behavior between polariton branches of plexciton spectra. Localization of surface modes on interfaces and hybridization between plasmons and excitons at both interfaces of exciton slab were proved by the time-averaged Poynting vector. We found that the types of coupling regimes between plasmons and excitons from weak to strong could be achieved. We obtained a high Rabi splitting energy 840 meV corresponding to the time period 5 fs which indicates to the fast energy transfer between surface plasmon polaritons and surface excitons. [ABSTRACT FROM AUTHOR]

The CdWO 4 :Yb 3+ (0.1, 2, 3%) nanophosphors have been synthesized using microwave-hydrothermal treatment. The spectral and kinetic characteristics of their luminescence were studied with the aim to check the possibility of cooperative energy transfer from CdWO 4 self-trapped excitons to Yb 3+ pairs, which can provide down-conversion of UV photons absorbed by the CdWO 4 host into two lower-energy (IR) photons emitted by two Yb 3+ ions. The obtained results have shown the conversion of absorbed UV photons into Yb 3+ IR fluorescence. However, the obtained parameters of decay kinetics of both intrinsic luminescence of CdWO 4 and IR fluorescence of Yb 3+ did not confirm the existence of cooperative energy transfer from STE to two Yb 3+ ions in the studied CdWO 4 :Yb 3+ nanophosphors. The reason is supposed to be rather low concentrations of Yb 3+ obtained in the synthesized samples which prevents the creation of high enough concentration of Yb 3+ pairs with short distances between the ions. [ABSTRACT FROM AUTHOR]

Phosphorescent white organic light emitting diodes (WOLEDs) with a multi-layer emissive structure comprising two separate blue layers and an ultra-thin red and green co-doped layer sandwiched in between have been studied. With proper host and dopant compositions and optimized layer thicknesses, high-performance WOLEDs having a power efficiency over 40 lm/W at 1000 cd/m 2 with a low efficiency roll-off have been produced. Through a systematic investigation of the exciton confinement and various pathways for energy transfer among the hosts and dopants, we have found that both the ultra-thin co-doped layer and two blue emitting layers play a vital role in achieving high device efficiency and controllable white emission. [ABSTRACT FROM AUTHOR]

The electronic properties of light-harvesting complexes determine the efficiency of energy transfer in photosynthetic antennae. Ab initio calculations of the electronic properties of bacteriochlorophylls (composing the LH1 complex of the purple bacteria Thermochromatium tepidum ) were performed. Based on these calculations, the excitonic Hamiltonian of a native cyclic complex and the Hamiltonians of open complexes with several removed bacteriochlorophylls were constructed. Absorption spectra calculated based on these Hamiltonians agree well with the experimental data. We found that the parameters of interaction between the neighboring bacteriochlorophylls are significantly larger than the empirical parameters suggested previously. [ABSTRACT FROM AUTHOR]

The non-doped ultra-thin emissive layer (EML) is a promising novel structure for fabricating organic light-emitting diodes (OLEDs). We attempt to perform exciton management in order to obtain a highly efficient and balanced light-emitting phosphorescent red–green–blue (RGB) white OLED (WOLED). These studies include optimization of the locations of the three RGB EMLs based on investigations concerning the spatial distribution of excitons, along with the energy transfer mechanisms between different materials. More importantly, by introducing a 1,1-bis((di-4-tolylamino)phenyl) cyclohexane (TAPC) interlayer, which acts as a hole-trapping layer, a redistribution of excitons is realized, giving rise to a more balanced white light emission. This simple method is an efficient way to adjust the exciton distribution, and could therefore be used in future OLED devices. [ABSTRACT FROM AUTHOR]

The performance of three color single emissive layer white phosphorescent organic light-emitting diodes (PHOLEDs), with different hole transporting materials of N,N′-diphenyl-N,N′-bis(l-naphthyl-phenyl)-(l,l′-biphenyl)-4,4′-diamine (NPB), 4,4_,4_-tris_N-carbazolyl_tri-Phenylamine (TCTA) and 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), was analyzed. It is found that the luminous efficiency of white PHOLEDs is closely related to the triplet exciton energy level in the hole transporting layer (HTL). White PHOLEDs with a TAPC as HTL, having the highest triplet exciton energy level amongst the three different hole transporting materials, yielded external quantum efficiency of 25.5% at 4.5 V and a high luminous efficiency of 51 cd/A at 4.5 V with CIE color coordinates of (0.34, 0.39) at 10 V. The results reveal that the effective confinement of triplet excitons in white PHOLEDs with a high triplet exciton energy level HTL (TAPC) allows improving the luminous efficiency, as compared to the devices made with NPB and TCTA. Additionally, we demonstrated possibility for the loss of intensity in EL spectra of the white PHOLED devices with NPB and TCTA as HTL compared to that of the device with TAPC as HTL. [ABSTRACT FROM AUTHOR]

We investigate the relevance of dynamic quantum coherence in the energy transfer efficiency of molecular aggregates. We derive the time evolution of the density matrix for an open quantum system excited by light or by a neighboring antenna. Unlike in the classical case, the quantum description does not allow for a formal decomposition of the dynamics into sudden jumps in an observable quantity - an expectation value. Rather, there is a natural finite time-scale associated with the excitation process. We propose a simple experiment to test the influence of this time scale on the yield of photosynthesis. We demonstrate, using typical parameters of the Fenna-Matthews-Olson (FMO) complex and a typical energy transfer rate from the chlorosome baseplate, that dynamic coherences are averaged out in the complex even when the FMO model is completely free of all dissipation and dephasing. [ABSTRACT FROM AUTHOR]

We synthesized Au nanoparticles (Au-NPs) encapsulated zinc oxide (ZnO:Au) nanosponges by the fraternization of ZnO nanoflowers with HCl (0–30 mM) concentrated colloidal Au-NPs at room temperature. The crystallite size (D) of mesoporous ZnO:Au decreased from 44 nm to 22 nm and the strain (τ) increased from 2.5 × 10−3 to 4.7 × 10−3 as the HCl concentration of colloidal Au-NPs increased from 0 mM to 30 mM. For elemental composition of ZnO:Au nanosponges, the STM-mapping confirmed the Au-NPs encapsulation on nanostructured ZnO. The bandgap, E g , and the Urbach energy, E u , of ZnO:Au decreased from 3.26 to 2.96 eV, and from 0.335 to 0.318 eV, as the colloidal Au-NPs increased from 0 mM to 30 mM, respectively. The structural and microstructure analysis showed the sponge like morphology along with wurtzite hexagonal structure of ZnO, which tuned the PL emission for the sensor selectivity. The visible emission of ZnO:Au nanosponges was greatly tuned from 600 nm to 500 nm with respect to the HCl diluted colloidal Au-NPs. The excellent photoluminescence (PL) performance of nanostructured ZnO:Au was attributed to the surface-plasmon-mediated sequential transfer of defect energy from ZnO to Au and electron transfer from excited Au to ZnO. [Display omitted] • Wurtzite hexagonal ZnO:Au nanosponges synthesized from ZnO nanoflowers and HCl diluted colloidal AuNPs. • The ' D ' decreased 44 → 22 nm and ' τ ' increased 2.5 × 10−3→4.7 × 10−3 w.r.t. HCl diluted AuNPs (0 mM → 30 mM). • E g & E u of ZnO:Au decreased from 3.26 to 2.96 eV, and from 0.335 to 0.318 eV as Au-NPs increased 0–30 mM. • Tuning of PL peak suggested to the defect energy from ZnO to Au and electron transfer from Au* to ZnO. • PL peak tuning from 1.66 eV to 2.48 eV by the DLE at the surface of ZnO and bound excitons. [ABSTRACT FROM AUTHOR]

Photoluminescence of non-stoichiometric silicon nitride films has been studied at excitation range 3.35–5.16 eV. Several bands with energies 3.15, 3.4, 3.62, 3.8, and 3.95 eV have been observed in the PL spectra. The bands at 3.62, 3.8, 3.95 eV assigned to exciton annihilation. Emission at energies 3.15 and 3.4 eV shifts in red spectrum region with excitation energy decreasing. The shift is explained by photo-induced neutralization of charged defect states and the emission can be associated with radiative recombination of charge carriers localized on donor-acceptor pairs. Energy-resolved photoluminescence method reveals the excitation energy transfer channels. It has been found that excitons participate in process of energy transfer to donor-acceptor pairs, providing 3.4 eV band position invariant to the excitation energy. • Photoluminescence of SiN x has several bands at 3.15, 3.4, 3.62, 3.8, and 3.95 eV. • Tree higher energy bands assigned to excitons, 3.15, 3.4 eV–to donor-acceptor pairs. • Excitation above bandgap is distributed between excitons and donor-acceptor pairs. • Excitons participate in transfer energy to donor-acceptor pairs with 3.4 eV band. • Majority of excited charge carriers recombines previously relaxing to lower states. [ABSTRACT FROM AUTHOR]

ATP production by mitochondria isolated from Saccharomyces cerevisiae cells was accelerated upon both direct and indirect mitochondrial photo-activation (MPA). The extent of direct MPA was dependent on the wavelength of excitation light. Direct MPA was created by light in cytochrome c spectral absorption bands (440, 520 and 550 nm), this light was absorbed producing electronically excited cytochrome c , and the excitation energy of the latter was used in the ATP production chain. The activity of cytochrome c was tested with 600 nm light, where cytochrome c does not absorb, and thus ATP production rate remained the same as in darkness. Note that ATP production rates were significantly larger under light at 550, 520 and 440 nm. Therefore, photo-activation of cytochrome c was the first step of MPA synthesis of ATP. Indirect MPA of ATP production also proceeded via electronically excited cytochrome c , by energy transfer from electronically excited Co/BN film to cytochrome c located in the inner mitochondrial membrane (IMM). Co/BN excitons were generated by photons absorbed by the Co/BN film, which was not in contact with the mitochondrial sample. Next, these excitons propagated along the Co/BN film to the part of the film that was in contact with the mitochondrial sample. There the exciton energy was transferred to cytochrome c located in the IMM, producing electronically excited cytochrome c. Thus, excited cytochrome c was generated in a way different from that of direct MPA. Next, the energy of excited cytochrome c was used in activated ATP synthesis, with virtually the same effect for 519 and 427 nm excitation. Thus, the first step of ATP synthesis in indirect MPA was the exciton energy transfer from Co/BN film to cytochrome c located in the IMM, producing an electronically excited cytochrome c molecule. A phenomenological mechanism of direct and indirect MPA was proposed, and the model parameters were obtained by fitting the model to the experimental data. However, more information is needed before the detailed mechanism of ATP synthesis activation by electronically excited cytochrome c could be understood. The present results support the earlier proposed hypothesis of indirect MPA of ATP production in vertebrate retina in daylight. [Display omitted] • ATP synthesis by yeast mitochondria was photo-activated by light at 440, 520 and 550 nm. • The same reaction was activated by exciton energy transfer from Co/BN nanofilm to mitochondrial cytochrome c. • Detailed theoretical model of mitochondrial photo-activation developed and discussed. [ABSTRACT FROM AUTHOR]

Colloidal CdTe quantum dots (QDs) of two different sizes (2.7 nm and 3.7 nm diameter) were self-assembled into mixed quantum dot donor-acceptor nanoclusters (QDANs) in aqueous solution. The ratio of small QDs (SQDs) to large QDs (LQDs) was 10:1, and the assembly was mediated by electrostatic attraction between oppositely-charged ligands (thioglycolic acid, TGA, and mercaptoethylamine, MA) on the QD surfaces. Under low excitation fluence (well below the threshold for biexciton formation), photoluminescence (PL) emission spectra and time-resolved decays in the QDANs revealed quenching in the SQDs and enhanced emission from the LQDs, providing evidence for resonance energy transfer (RET) from the wider band gap SQDs to the narrower band gap LQDs. The observed RET rate constant, determined from comparison of decays of free SQDs and those in the QDANs, was (3.4 ns)−1. Under these low-fluence conditions, the PL emission lifetimes of the LQDs in QDANs were the same as the free LQDs. Under higher excitation intensity, the decay of the LQDs in the QDAN showed a new, fast (sub-nanosecond), fluence-dependent component, suggesting formation of biexcitons and multiexcitons on the LQDs. The free LQDs required significantly (approximately 4-fold) higher excitation intensity than those in the QDANs to show similar evidence of biexciton formation through lifetime shortening. Since the QDANs contained a 10-fold excess of SQDs, the excitation energy that was initially distributed over the full population of QDs was funneled and concentrated into the small number of LQDs. These results support the idea that optical gain through biexciton formation can be enhanced by using RET, even when the rate constant for RET is much lower than that for biexciton decay. [Display omitted] • Nanocluster of CdTe quantum dots (QDs) assembled of two different sizes, small QDs (SQDs) and large QDs (LQDs). • Photoexcitation energy funnels in nanocluster from the SQDs to the LQDs, facilitating multiexciton formation in LQDs. • Multiexciton production in LQDs at lower-intensity pumping was proved by time-resolved photoluminescence. • This approach provides benefits in the design and development of new optical gain materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] We study exciton dynamics by ultrafast spectroscopies in DPA:PtOEP host–guest films. [•] Aggregation of PtOEP affects considerably the triplet energy transfer to DPA host. [•] No significant triplet loss due to TTA occurs within PtOEP aggregates. [•] Triplet energy transfer from PtOEP to DPA is slow and thermally activated process. [•] The ISC time in PtOEP is shorter than 100fs. [Copyright &y& Elsevier]

Abstract: In this paper, we study the two exciton energy transfer in an inhomogeneous alpha-helical protein chain by proposing a suitable model Hamiltonian. We build the theory of envelope solitons for this system based on the two trial functions proposed by Davydov after suitably modifying them for two exciton states. The underlying dynamics is investigated by constructing Lagrange’s equation of motion which is found to be a perturbed nonlinear Schrödinger (NLS) equation. The effect of nonlinear inhomogeneity in the form of modified exchange interaction between sites is studied in terms of a soliton under perturbation. The perturbed soliton is constructed using a sine–cosine method. It is found that the presence of inhomogeneity causes soliton splitting and hence a disorder in the protein molecular system. [Copyright &y& Elsevier]

Abstract: The authors observe that the external quantum efficiency (EQE) of the Iridium (III) bis(4-phenylthieno [3,2-c]pyridinato-N,C2′)acetylacetonate (PO-01) based yellow organic light-emitting diode (OLED) is significantly increased by uniformly co-doping Iridium (III)bis[(4,6-difluorophenyl)-pyridinato-N,C2−] (FIrpic) and PO-01 into the same wide band-gap host of N,N′-dicarbazolyl-3, 5-benzene (mCP). Detailed investigation indicates that the efficiency enhancement is ascribed to effective triplet exciton gathering by FIrpic, followed by energy transfer to PO-01. Compared to the control device, which has maximum EQE of 10.5%, an improved maximum EQE of 13.2% is obtained in the optimization white device based on FIrpic and PO-01 emission according to this principle. This work makes it easier for a single host white OLED to simultaneously harvest high efficiency in both blue and yellow units. Comprehensive experimental results show that this phenomenon can also be found and utilized in other popular hosts to realize more efficient white devices. [Copyright &y& Elsevier]

• Surface plasmon induced CsPbBr 3 photoluminescence enhancement. • The SiO 2 layer between Ag and CsPbBr 3 can modulate the photoluminescence enhancement. • Surface plasmon can increase the spontaneous emission rate. In this paper, we report CsPbBr 3 /SiO 2 /Ag hybrid thin films structure to realize the metal surface plasmon enhanced photoluminescence. The photoluminescence of CsPbBr 3 can be enhanced when the CsPbBr 3 excitons interact with surface plasmon from Ag thin film. The numerical simulation demonstrates the localized electric field induced by surface plasmon is the strongest when SiO 2 interlayer has the thickness of 5 nm. If taking account of the energy transfer from CsPbBr 3 excitons to Ag layer, the experimental maximum photoluminescence enhancement factor actually occurs when the SiO 2 thin film has a thickness of 20 nm. The temperature-dependent photoluminescence demonstrates that metal surface plasmon enhanced photoluminescence has higher enhancement factor at lower temperature, which is attributed to the stronger surface plasmon coupling efficiency at low temperature. The time-resolved photoluminescence further proves that the surface plasmon coupling can enhance the spontaneous emission rate at low temperature. [ABSTRACT FROM AUTHOR]

Herein, we report CdSe quantum dots (QDs)-decorated ZnIn 2 S 4 nanosheets for "signal-on" photoelectrochemical (PEC) aptasensing of adenosine triphosphate (ATP) by integrating exciton energy transfer with exciton-plasmon coupling. Under visible light irradiation, the CdSe/ZnIn 2 S 4 shows higher PEC activity than ZnIn 2 S 4 nanosheets and CdSe QDs resulting from the formation of n-n type heterojunction. To construct a PEC aptasensor, Au nanoparticle (AuNP)-labeled short DNA strand (denoted as c -DNA) is immobilized on the CdSe/ZnIn 2 S 4 modified indium tin oxide (ITO) electrode and then hybridized with an aptamer to yield a double-stranded DNA. Before ATP incubation, AuNPs are kept away from the CdSe/ZnIn 2 S 4 /ITO, so the exciton energy transfer between CdSe QDs and AuNPs greatly quenches the photocurrent ("signal-off" state). After ATP incubation, AuNPs labeled on the c -DNA are in close contact with the CdSe/ZnIn 2 S 4 /ITO, and an increased photocurrent can be obtained due to the great exciton-plasmon coupling effect ("signal-on" state). This distance-triggered signaling "off–on" strategy enables sensitive aptasensing of ATP, with a broad linear range from 0.2 pM to 1 μM and a detection limit of 0.1 pM. • CdSe QDs-decorated ZnIn 2 S 4 nanosheets are exploited as highly active photoactive materials. • ATP-induced DNA structure switch enables distance regulation between AuNPs and CdSe QDs. • A "signal-on" photoelectrochemical aptasensor is constructed based on distance-triggered signaling "off–on" strategy. • Great signal amplification is achieved by integrating exciton energy transfer with exciton-plasmon coupling. • The detection limit for photoelectrochemical detection of ATP is as low as 0.1 pM. [ABSTRACT FROM AUTHOR]