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[Display omitted] • First synthesis of well-defined mono-fluorine end-substituted nonfullerene acceptors. • Facile preparations of the asymmetric and symmetric isomers through one reaction and one column chromatography. • The highest efficiency among binary OSCs with low cost oligothiophene-based polymers as the donor. • The highest efficiency among binary OSCs based on mono-fluorine end-substituted nonfullerene acceptors. In the field of non-fullerene organic solar cells (OSCs), most of the promising non-fullerene acceptors (NFAs) are based on bi-fluorinated 1,1-dicyanomethylene-3-indanone (IC) while NFAs with mono-fluorinated IC have drawn less attenton because of low device performances. Herein, two NFA isomers BTzC 4 IC-2F- δγ and BTzC 4 IC-2F- δ , with benzotriazole-fused core and mono-fluorine end-substituted IC, were facilely synthesized and separated via direct column chromatography method. Based on the asymmetric and symmetric isomers, the isomeric effect for the mono-fluorination on IC were investigated, indicating BTzC 4 IC-2F- δγ possessing upper-lying energy levels while BTzC 4 IC-2F- δ showing red-shifted absorption, stronger intramolecular interaction, and higher electron mobility. Oligothiophene-based terpolymer PFBT4T-T20 with low-cost potential was selected as the donor, and the BTzC 4 IC-2F- δ based active layer afforded longer carrier lifetime and shorter charge extraction time as well as more intense and wider photoresponses to achieve external quantum efficiency of 64 % at 900 nm. The BTzC 4 IC-2F- δ based OSCs showed slightly lower open-circuit voltage but obviously enhanced short-circuit current density and fill factor, finally achieving a higher power conversion efficiency of 17.82 % than that of 16.91 % for the BTzC 4 IC-2F- δγ based device. The best efficiency of 17.82 % achieved with BTzC 4 IC-2F- δ is the highest one among binary OSCs with oligothiophene-based polymers as the donor and also the highest one among OSCs based on mono-fluorine end-substituted NFAs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic RTP of ultralong lifetime and high quantum efficiency was presented. • Phosphorescence mechanism based on the excited states regualtion was proposed. • Multilevel information encryption based on liftetimes and colors was shown. Organic room-temperature phosphorescence (RTP) with ultralong lifetime and high quantum efficiency is of interest but challenging. Few phosphor systems in the monomer state demonstrate lifetimes over 0.1 s with quantum efficiencies exceeding 10% due to the lack of molecular design principle and qualified molecular system. Here we present a novel class of phosphors based on heteroaromatic sulfone-locked triphenylamine core BTPO with rational subunit modification that displays ultralong RTP in a doped polymer matrix with lifetimes up to 818 ms and quantum efficiencies over 20% simultaneously. The co-win situation is attributed to an efficient and multichannel intersystem crossing (ISC) process arising from narrower singlet-triplet exchange energy and strong spin-orbital coupling interaction between the lowest singlet state (S 1) and high-lying triplet states that facilitate numerous triplet excitons generation, as well as a relatively pure (π, π*) configuration for the lowest triplet state (T 1), ensuring the small radiative rate of phosphorescence (k p) and consequently ultralong lifetime. Taking advantage of RTP features with the multicolor and diverse lifetime of this phosphor family, the primary application in information encryption is well demonstrated versatilely. [ABSTRACT FROM AUTHOR]

We used Drosophila as an animal model to study the digestive tract in response to the exposure of inorganic mercury (HgCl 2 ). We found that after oral administration, mercury was mainly sequestered within the midgut. This resulted in increased cell death, which in turn stimulated the tissue regeneration program, including accelerated proliferation and differentiation of the intestinal stem cells (ISCs). We further demonstrated that these injuries correlate closely with the excessive production of the reactive oxygen species (ROS), as vitamin E, an antioxidant reagent, efficiently suppressed the HgCl 2 -induced phenotypes of midgut and improved the viability. We propose that the Drosophila midgut could serve as a suitable model to study the treatment of acute hydrargyrism on the digestive systems. [ABSTRACT FROM AUTHOR]

Fluorescent/phosphorescent hybrid white organic light-emitting diodes (WOLEDs) combining blue aggregation-induced emission (AIE) fluorophors with efficient yellow (or green/red) phosphors have attracted more attention in applications of full-color display and solid-state lighting. However, it is still a major challenge for hybrid WOLEDs based on AIE-active fluorophors to simultaneously realize high efficiency, high color rendering index (CRI), good color stability and low efficiency roll-off. Here, a sky-blue AIE fluorophor as the neat emitter has been successfully applied to high-performance blue OLED and two-/three-color hybrid WOLEDs. The blue device with a high exciton utilization efficiency of 47.4%–71.1% realizes the external quantum efficiencies (EQEs) of 6.3 and 5.5% at 1000 and 5000 cd m−2. By accurately managing the arrangement of emissive layers, Three-color WOLED without the damage of deep-blue light not only realizes high efficiencies of 41.6 cd A−1 and 46.6 lm W−1, but also shows a high CRI over 80 and good color stability with the Commission Internationale de L'Eclairage (CIE) coordinates changing from (0.432, 0.480) to (0.418, 0.488) when the driving voltage increases from 4 to 7 V, meeting the requirement for energy-saving and healthy lighting source. Such excellent EL performance is really rare in the no deep-blue light damage, high CRI and good color stability hybrid WOLEDs based on AIE-active fluorophor. High efficiency hybrid WOLEDs with no deep-blue light damage, good color stability, and high CRI over 80 have been achieved based on blue aggregation-induced emission fluorophor. [Display omitted] • A blue AIE-active fluorophor realizes theEQEs of 6.3 and 5.5% at 1000 and 5000 cd m−2. • The WOLED with no deep-blue light damage, high CRI over 80, and color stability is realized. • The WOLED shows the -forward-viewing current efficiency of 41.6 cd A−1, and remains as high as 38.7 and 36.8 cd A−1 at 100 and 1000 cd m−2. [ABSTRACT FROM AUTHOR]

In this work, we used five different fluorescent hosts and six phosphorescent guests to study the effect of the relationship between the energy levels of host and guest on the EL performance of phosphorescence organic light-emitting diodes (PHOLEDs). The experimental results show clearly that the difference between triplet energy levels of the used host and guest plays an important role, and the electron and hole injection barriers, respectively, from electron-transporting layer (ETL) and hole-transporting layer (HTL) into emitting layer (EML) and the mobility of ETL also have a certain influence. It can be seen that the triplet energy level of hosts should be higher than that of guests and the distance between them is as close as possible, ensuring the effective energy transfer from hosts to guests. Furthermore, it is also necessary to have low injection barriers into EML for electrons and holes, and high electron mobility of ETL, which guarantee electrons and holes injected effectively and evenly. This further explains the fundamental reason why the fabrication of high efficiency PHOLEDs must optimize the host, guest and match transporting layers. Our studies will help to establish better design rules for host-guest systems to achieve high performance PHOLEDs. Study the effect of the relationship between the energy levels of hosts and guests and the mobility of ETLs on the EL performance of PHOLEDs. [Display omitted] • Study the effect of the relationship between the energy levels of host and guest on the EL performance of PHOLEDs. • The higher T 1 of host than that of guest and the LUMO and HOMO levels of guest within those of host are important. • Low injection barriers and high electron mobility of ETL are effective for carriers to inject and recombine in EML. [ABSTRACT FROM AUTHOR]

The charge generation mechanism of organic heterojunction (OHJ) consisted of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) and different hole transporting materials (HTMs) are studied systematically by current-voltage (I–V) and capacitance-voltage measurements. The analysis of I–V characteristics of the devices based on OHJs at forward and reverse voltages by comparing the thickness of HTM layers finds that a forward and reverse symmetrical I–V curve is observed at thin HTM layers and the forward current becomes larger than the reverse current with the increase of HTM thickness, fully illustrating the effectiveness of OHJ charge generation. Moreover, the I–V characteristics at different temperatures indicate that the efficient charge generation is originated from electron tunneling rather than diffusion. And the C–V and capacitance-frequency (C–F)characteristics further illustrate the highly efficient charge generation ability of OHJs so that the charge density is as high as 4.5 × 1017 cm−3, guaranteeing the high conductivity of OHJs, which is very beneficial to developing highly efficient OLEDs using OHJs as charge injector and generator. The mechanism of charge generation in orgainc heterojunctions have been systematically studied via the analysis of I–V and C–V characteristics, which not only reveals that the highly efficient charge generation process is originated from the electron tunneling rather than the diffusion, but also exhibited the high charge density (4.5 × 1017 cm−3), ensure the high conductivity of OHJs. Image 1 • The charge generation process of OHJ is studied via the analysis of I–V and C–V characteristics. • The electron tunneling model of charge generation process is revealed. • The free charge density of OHJ is calculated as high as 4.5 × 1017 cm−3. [ABSTRACT FROM AUTHOR]

White organic light-emitting diodes (WOLEDs) have widely drawn attention for applications in flat panel display and solid-state lighting. High efficiency and simple device structure are two important factors for large-scale application for WOLEDs. Here, we have presented a relatively reliable method to develop high-performance and doping-free WOLEDs by integrating interfacial exciplex with phosphorescent multi-ultrathin emissive layers. By reasonable design of device architecture, the resulting WOLED with a warm-white light not only realizes a low turn-on voltage of 2.25 V, but also exhibits the high forward-viewing power efficiency and external quantum efficiency of 91.5 lm W−1 and 21.3%, respectively, without light out-coupling enhancement techniques. More importantly, the power efficiency still remain as high as 49.5 lm W−1 at the high luminance of 1000 cd m−2, which should be one of the best values in reported doping-free WOLEDs. It suggests that multi-ultrathin emissive layers combining with interfacial exciplex can realize the efficient utilization of excitons and improvement of efficiency roll-off. High-performance doping-free WOLED was achieved by separating exciton recombination and emission zone and increasing energy transfer channels based on interfacial exciplex. Image 1 • A high-performance doping-free WOLED was achieved by combining interfacial exciplex with multi-ultrathin emissive layers. • The WOLED with a low turn-on voltage of 2.25 V and realized a high forward-viewing power efficiency of 21.3% and 91.5 lm W−1. • EL performance of the resulting WOLED is one of the best values in reported doping-free WOLEDs. [ABSTRACT FROM AUTHOR]

White organic light-emitting diodes (WOLEDs) with ultra-thin emitting layers have shown considerable potential in solid-state lighting fields due to the simplified structures. However, such WOLEDs with high efficiency, high color rendering index (CRI) and stable spectral emission are still facing challenges. In this paper, we demonstrated a high efficiency and high CRI phosphorescent WOLED by strategically adjusting the positions of red, green and blue phosphorescent ultra-thin layers in exciplex emitter. By investigating the processes of energy transfer and utilization of triplet excitons, a high efficiency, high CRI and stable spectrum emission warm WOLED was successfully fabricated. The maximum external quantum efficiency (EQE), power efficiency (PE) and current efficiency (CE) reached 26.1%, 50 lm W−1,and 40 cd A−1, respectively, and the CRI was as high as 80 in the luminance range from 1000 cd m−2 to 30000 cd m−2 with stable emission spectra, exhibiting superior comprehensive EL performances. This work also indicates the potential of undoped ultra-thin layer structures to fabricate high performance WOLEDs for lighting applications. High efficiency and color quality White Organic Light-emitting Diodes have been demonstrated by strategically adjusting the positions of red, green and blue phosphorescent ultrathin layers in exciplex emitter and adding another channel to fully utilized CT state excitons. Image 1 • A doping-free white organic light-emitting diode can sufficiently simplify the device's structure and lower the cost. • The efficiency has been improved by strategically establishing another channel for blue emission to fully use excitons. • A full-phosphorescent WOLED with high efficiency, high color quality has been achieved based on exciplex. [ABSTRACT FROM AUTHOR]

An efficient planar organic heterojunction (OHJ) consisted of 1,4,5,8,9,11-hexaazatriphenylene- hexacarbonitrile (HAT-CN)/1,1-bis [(di-4-tolyamino)phenyl)]cyclohexane (TAPC) is employed simultaneously as both charge generation layer (CGL) and charge injectors to fabricate high efficiency and long lifetime tandem organic light-emitting diodes (OLEDs). It can be seen that compared with conventional tandem OLEDs, the tandem OLEDs utilizing OHJ as both CGL and charge injectors significantly improved not only the current and quantum efficiencies, more importantly, but also the power efficiency and stability. The maximum efficiencies were as high as 42.0%, 159.5 cd A-1 and 92.7 lm W-1, and the lifetime reached 1350 h, which are more higher than the efficiencies of 34.3% 130.2 cd A-1 and 75.0 lm W-1 and the lifetime of 859 h of conventional tandem OLEDs. The more balanced charge generation and injection due to the simultaneous utilization of OHJ as CGL and charge injectors contributed to the significant improvement in the performance of resulting tandem OLEDs. These results fully indicate the validity of OHJ as CGL and charge injectors, and also provide a new route for the development of high performance OLEDs. High efficiency and long lifetime tandem OLEDs that utilize HAT-CN/TAPC (OHJs) as both charge generation layer (CGL) and charge injectors are fabricated, achieving a novel charge injection way, which is not only different from the injection via electrodes in traditional OLEDs, but also is benefical to realize the more balanced charge injection. Image 1 • Organic heterojunction HAT-CN/TAPC simultaneously as both charge generation layer and charge injectors is proposed. • High efficiency and long lifetime tandem OLEDs based HAT-CN/TAPC are successfully fabricated. • The more balanced charge generation and injection are realized in studied OLEDs. [ABSTRACT FROM AUTHOR]

Polycyclic heteroaromatics (PHAs) are a highly versatile class of functional materials, especially applicable as efficient luminophores in organic light-emitting diodes (OLEDs). Those constructed by tethered phenyl surrounding the main group center attract extensive attention due to their excellent OLED device performance. However, the development of such a class of emitters is often limited to boron, nitrogen-doped π-conjugated heterocycles. Herein, we proposed a novel kind of blue emitter by constructing a donor-acceptor molecular configuration, utilizing a dual sulfone-bridged triphenylamine (BTPO) core and mono/di-diphenylamine (DPA) substituents. The twisted D-A molecular structures and appropriate donor strength facilitate the effective separation of natural transition orbitals, endowing the emitters with charge-transfer dominant hybridized local and charge-transfer characteristics for the excited states. Both BTPO-DPA and BTPO-2DPA own small S 1 -T 1 splitting energy, thus demonstrating blue thermally activated delayed fluorescence. The more symmetrical structure and enhanced CT features brought by additional DPA moiety confer BTPO-2DPA with a shorter delayed fluorescence lifetime, a higher fluorescence quantum yield and narrower emission. Therefore, BTPO-2DPA based OLED devices exhibit superior blue electroluminescence performance, with external quantum efficiencies reaching 12.31 %., (© 2024 Wiley-VCH GmbH.)

The thermally activated delayed fluorescence (TADF)-sensitized fluorescent (TSF) dye strategy has been used successfully in thermally evaporated organic light-emitting diodes (eOLEDs), but the development of solution-processed TSF-OLEDs (TSF-sOLEDs) is still very limited to date. Previously, the introduction of electronically inert shielding terminal groups for TADF sensitizer and/or fluorescent dyes was commonly used in TSF-sOLEDs, which aimed to achieve sufficient Förster energy transfer (FET) while restraining notorious Dexter energy transfer (DET) at a high doping concentration of fluorescent dyes. However, this approach has not yet enabled efficient TSF-sOLEDs owing to severe charge trapping emission (CTE) for triplet loss. In this study, by simply utilizing highly efficient boron-dipyrromethene derivatives (BODIPYs) that simultaneously feature high fluorescent quantum efficiency and narrow-band emission spectra, we developed highly efficient and super color-purity TSF-sOLEDs using a 0.1 wt% ultralow doping strategy. As confirmed, the resultant ultralow doping TSF-sOLEDs achieved sufficient FET from sensitizer to fluorochrome without noticeable CTE issues. The device achieves record maximum external quantum efficiency (EQE max ) and current efficiency (CE max ) of 21.5% and 78.8 cd A -1 , respectively, and an ultrapure green emission with Commission International de l'Eclairage (CIE) coordinates of (0.28, 0.65). This study validates the new device architecture of ultralow doping TSF-sOLEDs, which paves the way for future development of high-resolution TSF-sOLED displays via a simple solution-processed manufacturing approach.

Currently, much research effort has been devoted to improving the exciton utilization efficiency and narrowing the emission spectra of ultraviolet (UV) fluorophores for organic light-emitting diode (OLED) applications, while almost no attention has been paid to optimizing their light out-coupling efficiency. Here, we developed a linear donor-acceptor-donor (D-A-D) triad, namely CDFDB, which possesses high-lying reverse intersystem crossing (hRISC) property. Thanks to its integrated narrowband UV photoluminescence (PL) (λ PL : 397 nm; FWHM: 48 nm), moderate PL quantum yield (ϕ PL : 72 %, Tol), good triplet hot exciton (HE) conversion capability, and large horizontal dipole ratio (Θ // : 92 %), the OLEDs based on CDFDB not only can emit UV electroluminescence with relatively good color purity (λ EL : 398 nm; CIE x,y : 0.161, 0.040), but also show a record maximum external quantum efficiency (EQE max ) of 12.0 %. This study highlights the important role of horizontal dipole orientation engineering in the molecular design of HE UV-OLED fluorophores., (© 2024 Wiley-VCH GmbH.)

The lifetime of blue organic light-emitting diodes (OLEDs) has always been a big challenge in practical applications. Blue OLEDs based on triplet-triplet annihilation (TTA) up-conversion materials have potential to achieve long lifetimes due to fusing two triplet excitons to one radiative singlet exciton, but there is a lack of an in-depth understanding of exciton dynamics on degradation mechanisms. In this work, we established a numerical model of exciton dynamics to study the impact factors in the stability of doped blue OLEDs based on TTA up-conversion hosts. By performing transient electroluminescence experiments, the intrinsic parameters related to the TTA up-conversion process of aging devices were determined. By combining the change of excess charge density in the emitting layer (EML) with aging time, it is concluded that the TTA materials are damaged by the excess electrons in the EML during ageing, which is the main degradation mechanism of OLEDs. This work provides a theoretical basis for preparing long-lifetime blue fluorescent OLEDs.

Aggregation-induced delayed fluorescence (AIDF) materials have great potential in non-doped OLEDs due to their high photoluminescence (PL) quantum efficiency in film, high exciton utilization in the aggregated state and negligible efficiency roll-off at high luminance. However, their efficient mechanism in OLEDs is not yet well understood. Here, the exciton dynamics are used to investigate the electroluminescence (EL) mechanism of an AIDF emitter (4-(10 H -phenoxazin-10-yl)phenyl)-(9-phenyl-9 H -carbazol-3-yl)methanone (CP-BP-PXZ) in detail. It can be seen that the high efficiency and negligible efficiency roll-off in non-doped OLEDs based on CP-BP-PXZ as the emitter are ascribed to the effective reverse intersystem crossing (RISC) from high level triplet T 2 to singlet S 1 in the aggregated state. Furthermore, CP-BP-PXZ also exhibits excellent properties as a phosphor host due to its good AIDF properties. Thus, high-efficiency red phosphorescent OLEDs with low roll-off efficiency are successfully fabricated based on CP-BP-PXZ as the host. The maximum external quantum efficiency (EQE max ) reaches 23% and is maintained at 21% at a luminance of 1000 cd m -2 .

Nonfullerene-acceptor-based organic solar cells (NFA-OSCs) are now set off to the 20% power conversion efficiency milestone. To achieve this, minimizing all loss channels, including nonradiative photovoltage losses, seems a necessity. Nonradiative recombination, to a great extent, is known to be an inherent material property due to vibrationally induced decay of charge-transfer (CT) states or their back electron transfer to the triplet excitons. Herein, it is shown that the use of a new conjugated nitroxide radical polymer with 2,2,6,6-tetramethyl piperidine-1-oxyl side groups (GDTA) as an additive results in an improvement of the photovoltaic performance of NFA-OSCs based on different active layer materials. Upon the addition of GDTA, the open-circuit voltage (V OC ), fill factor (FF), and short-circuit current density (J SC ) improve simultaneously. This approach is applied to several material systems including state-of-the-art donor/acceptor pairs showing improvement from 15.8% to 17.6% (in the case of PM6:Y6) and from 17.5% to 18.3% (for PM6:BTP-eC9). Then, the possible reasons behind the observed improvements are discussed. The results point toward the suppression of the CT state to triplet excitons loss channel. This work presents a facile, promising, and generic approach to further improve the performance of NFA-OSCs., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

The stability and degradation mechanism of phosphorescent organic light emitting diodes (OLEDs) has been an unresolved problem in the past decades. Here, we found that electron accumulation at the interface between the electron blocking layer and the emitting layer is one of the reasons for device degradation. By inserting a thin layer with a shallower LUMO level than that of the electron transporting layer between the emitting layer and the electron transporting layer, we successfully reduced the density of electrons at the interface and greatly improved the lifetime of the resulting green phosphorescent OLEDs. The half decay lifetime LT 50 at the initial luminance of 1000 cd m -2 reached as high as 399 h, which is 1.7 times longer than that of the compared device without a thin layer.

Aggregation-induced emission (AIE) materials are attractive for the fabrication of high efficiency organic light-emitting diodes (OLEDs) by harnessing "hot excitons" from the high-lying triplet exciton states (T n , n ≥ 2) and high photoluminescence (PL) quantum efficiency in solid films. However, the electroluminescence (EL) efficiency of most AIE-based OLEDs does not meet our expectation due to some unrevealed exciton loss processes. Herein, we further enhance the efficiency of blue AIE-based OLEDs, and find experimentally and theoretically that the serious exciton loss is caused by the quenching of radiative singlet excitons and long-lived triplet excitons [singlet-triplet annihilation (STA)]. In order to suppress the STA process, 1-(2,5-dimethyl-4-(1-pyrenyl)phenyl)pyrene (DMPPP) with triplet-triplet annihilation up-conversion was doped in two AIE emitters to reduce the triplet excitons on the lowest triplet excited state (T 1 ) of AIE molecules. It can be seen that the external quantum efficiency (EQE) of the resulting blue OLEDs was enhanced to 11.8% with CIE coordinates of (0.15, 0.07) and a negligible efficiency roll-off, realizing the efficiency breakthrough of deep-blue AIE-based OLEDs. This work establishes a physical insight in revealing the exciton loss processes and the fabrication of high-performance AIE-based OLEDs.

The transient electroluminescence (EL) technique is widely used to evaluate the carrier mobility in the field of organic light emitting diodes. The traditional analog detection strategy using oscilloscopes is generally limited since the background noise causes an underestimation of the mobility value. In this paper, we utilize time-correlated single-photon counting (TCSPC) to probe the transient EL for mobility calculation. The measurements on tris(8-hydroxyquinoline) aluminum (Alq 3 ) show that the electron mobilities obtained using the TCSPC technique are slightly higher than those obtained from the analog method at all the investigated voltages. Moreover, the TCSPC mobilities demonstrate weaker dependence on the root of electrical field compared to the oscilloscope mobilities. These improvements are attributed to the unique principle of TCSPC, which quantifies the EL intensity by counting the number of single-photon pulses, improving its single-photon sensitivity and eliminating the negative impacts of electrical noise. These advantages make TCSPC a powerful technique in the characterization of time-resolved electroluminescence., (© 2022. The Author(s).)

Most organic semiconductors have closed-shell electronic structures, however, studies have revealed open-shell character emanating from design paradigms such as narrowing the bandgap and controlling the quinoidal-aromatic resonance of the π-system. A fundamental challenge is understanding and identifying the molecular and electronic basis for the transition from a closed- to open-shell electronic structure and connecting the physicochemical properties with (opto)electronic functionality. Here, we report donor-acceptor organic semiconductors comprised of diketopyrrolopyrrole and naphthobisthiadiazole acceptors and various electron-rich donors commonly utilized in constructing high-performance organic semiconductors. Nuclear magnetic resonance, electron spin resonance, magnetic susceptibility measurements, single-crystal X-ray studies, and computational investigations connect the bandgap, π-extension, structural, and electronic features with the emergence of various degrees of diradical character. This work systematically demonstrates the widespread diradical character in the classical donor-acceptor organic semiconductors and provides distinctive insights into their ground state structure-property relationship., (© 2021. The Author(s).)

Aggregation-induced emission (AIE) materials are attractive for achieving highly efficient nondoped organic light-emitting diodes (OLEDs) owing to their strong luminescence in the solid state. However, the electroluminescence efficiency of most AIE-based OLEDs remains low owing to the waste of triplet excitons. Here, using theoretical calculations, photophysical dynamics, and magnetoluminescence measurements, the spin conversion process is demonstrated between the high-lying triplet state (T n ) and the lowest excited singlet state (S 1 ) in AIE materials. Moreover, the relative positions of T n (n < 4) and S 1 are shown to have a significant impact on the spin-conversion efficiency, thus influencing the harvesting of triplet excitons and the device efficiency. Finally, by selecting an upconversion material with an appropriate energy level for further utilizing the triplet excitons, a deep-blue fluorescent OLED with CIE coordinates of (0.15, 0.08), a maximum external quantum efficiency of 10.2%, low efficiency roll-off, and a high brightness of 16817 cd m -2 is developed. This is one of the most efficient deep-blue OLEDs based on AIE materials reported so far. These findings also provide new insights into the design of more efficient AIE molecules and corresponding OLEDs by managing high-lying triplet excitons., (© 2021 Wiley-VCH GmbH.)

The emerging thermally activated delayed fluorescence materials have great potential for efficiencies in organic light-emitting diodes by optimizing molecular structures of the emitter system. However, it is still challenging in the device structural design to achieve high efficiency and stable device operation in white organic light-emitting diodes. Here we propose a universal design strategy for thermally activated delayed fluorescence emitter-based fluorescent white organic light-emitting diodes, establishing an advanced system of "orange thermally activated delayed fluorescence emitter sensitized by blue thermally activated delayed fluorescence host" combined with an effective exciton-confined emissive layer. Compared to reference single-layer and double-layer emissive devices, the external quantum efficiency improves by 31 and 45%, respectively, and device operational stability also shows nearly fivefold increase. Additionally, a detailed optical simulation for the present structure is made, indicating the validity of the design strategy in the fluorescent white organic light-emitting diodes.

The bird cherry-oat aphid, Rhopalosiphum padi (L.), is one of the most important wheat pests. This aphid damages through direct feeding and by transmitting the Barley yellow dwarf virus (BYDV). Both types of damage significantly reduce the quality and yield of wheat crops globally. Insecticides are the primary method of controlling the bird cherry-oat aphid in China, yet this aphid species has developed resistance to different types of insecticides, especially organophosphates and carbamates. In the last decade, control of R. padi depends primarily on the spray of neonicotinoid insecticides, however, research on the resistance of R. padi to neonicotinoids has been limited. In this study, the full lengths of seven α-subunit (Rpα1, Rpα2, Rpα3, Rpα4, Rpα5, Rpα7-1, and Rpα7-2) and one β-subunit (Rpβ1) genes from R. padi were obtained with RT-PCR and RACE techniques. Sequence analysis showed that these genes had all the characteristics of the nAChR gene family and were highly homologous with the reported nAChR genes from other insects, and alternative splicing was detected in Rpα3 and Rpα5 subunits. Analysis of the cDNA sequence of the extracellular region of the nicotinic acetylcholine receptor β1 subunit gene from 120 R. padi field samples collected in 11 Provinces revealed 17 single nucleotides polymorphism (SNP) sites, of which seven were amino acid polymorphism sites (V53I, V53G, N54T, A60T, F61L, W79C, and V83I) and two were in the loop D region (W79C and V83I). The current study will facilitate further studies on the molecular mechanisms of targeted resistance of the aphid to neonicotinoid insecticides., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We constructed shRNA vectors with different stem length, and tested the silencing effectiveness in mouse cells and embryos. We designed interfering RNAs with stems of 21 bp, 27 bp, and 29 bp. The enhanced green fluorescent protein gene was used as target gene. The synthesized single strands were annealed and cloned into psiSTRIKE and the recombinant plasmids (EGFP-21 siRNA, EGFP-27 siRNA, and EGFP-29 siRNA) were transfected into the mouse embryonic fibroblast with lipofection. The mRNA expression level of the enhanced green fluorescent protein gene was checked by real-time quantitative PCR. The silencing effectiveness of the 29 bp shRNA vector was stronger than which of the 21 bp and 27 bp. The findings in this study are of interest for selecting the hairpins for mouse individuals.