Quasi‐2D perovskites have long been considered to have favorable “energy funnel/cascade” structures and excellent optical properties compared with their 3D counterparts. However, most quasi‐2D perovskite light‐emitting diodes (PeLEDs) exhibit high external quantum efficiency (EQE) but unsatisfactory operating stability due to Auger recombination induced by high current density. Herein, a synergetic dual‐additive strategy is adopted to prepare perovskite films with low defect density and high environmental stability by using 18‐crown‐6 and poly(ethylene glycol) methyl ether acrylate (MPEG‐MAA) as the additives. The dual additives containing COC bonds can not only effectively reduce the perovskite defects but also destroy the self‐aggregation of organic ligands, inducing the formation of perovskite nanocrystals with quasi‐core/shell structure. After thermal annealing, the MPEG‐MAA with its CC bond can be polymerized to obtain a comb‐like polymer, further protecting the passivated perovskite nanocrystals against water and oxygen. Finally, state‐of‐the‐art green PeLEDs with a normal EQE of 25.2% and a maximum EQE of 28.1% are achieved, and the operating lifetime (T50) of the device in air environment is over ten times increased, providing a novel and effective strategy to make high efficiency and long operating lifetime PeLEDs.
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of ∼80%) and protons (with a polarization of ∼70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3) × 1033 cm−2 · s−1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
High-spin states in 161 Er have been studied experimentally using the 150 Nd( 16 O,5n) reaction at a beam energy of 86 MeV. The 5/2 + [642], 3/2 − [521], and 11/2 − [505] bands are extended up to high-spin states, and particularly the α = −1/2 branch of the ground state 3/2 − [521] band is revised significantly. The relatively enhanced E1 transitions from the 3/2 − [521] band to the 5/2 + [642] band are observed. The band properties are analyzed within the framework of a triaxial particle-rotor model, and near-prolate shape and triaxial deformation are proposed to the 3/2 − [521] and 5/2 + [642] bands, respectively. Signature inversion occurs in the 3/2 − [521] band after the band crossing in 161 Er, and the systematics of the signature inversion associated with the 3/2 − [521] configuration are discussed. By analyzing the properties of the relatively enhanced E1 transitions, it is found that the R(E1/E2) values show angular momentum dependence before the band crossing, and these enhanced E1 transitions could be attributed to octupole softness.
To tackle the issue in deep crowd sensing, a Time and Location Correlation Incentive (TLCI) scheme is proposed for deep data gathering in crowdsourcing networks. In TLCI scheme, a metric named "Quality of Information Satisfaction Degree" (QoISD) is to quantify how much collected sensing data can satisfy the application's QoI requirements mainly in terms of data quantity and data coverage. Two incentive algorithms are proposed to satisfy QoISD with different view. The first algorithm is to ensure that the application gets the specified sensing data to maximize the QoISD. Thus, in the first incentive algorithm, the reward for data sensing is to maximize the QoISD. The second algorithm is to minimize the cost of the system while meeting the sensing data requirement and maximizing the QoISD. Thus, in the second incentive algorithm, the reward for data sensing is to maximize the QoISD per unit of reward. Finally, we compare our proposed scheme with existing schemes via extensive simulations. Extensive simulation results well justify the effectiveness of our scheme. The QoISD can be optimized by 81.92%, and the total cost can be reduced by 31.38%.
Purely organic luminescent materials concurrently exhibiting thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) features are in great demand due to their high efficiency in aggregationstate toward efficient nondoped OLEDs. Herein, a class of TADF emitters adopting phenyl(pyridyl)methanone as electron-accepting segments and di(tert-butyl)carbazole and 9,9-dimethyl-9,10-dihydroacridine (or phenoxazine) as electron-donating groups are designed and synthesized. The existence of intramolecular hydrogen bonding is conducive to minish the energy difference between a singlet and a triplet (ΔE st ), suppress nonradiative decay, and increase the luminescence efficiency. By using 3CPyM-DMAC as the emitter, the nondoped device via a solution process realize a high current efficiency (CE) and external quantum efficiency (EQE) of 35.4 cd A −1 and 11.4%, respectively, which is superior to that of CBM-DMAC with a CE and EQE of 14.3 cd A −1 and 6.7%. This work demonstrates a promising tactic to the establishment of TADF emitters with AIE features via introducing intramolecular hydrogen bonding.
A water-soluble fluorescent probe for Zn2+based on a Schiff base derivative was prepared. It displays a rapid response toward Zn2+with selectivity and sensitivity and has been successfully applied to imaging in living cells.
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