Multiple donor-acceptor(D-A) combinations represent a promising category of thermally activated delayed fiuorescence(TADF) materials, offering potential for superior efficiency and stability. However, current systems ...Multiple donor-acceptor(D-A) combinations represent a promising category of thermally activated delayed fiuorescence(TADF) materials, offering potential for superior efficiency and stability. However, current systems are predominantly composed of limited donor groups, primarily carbazole-based derivatives. In this work, we developed a series of D-A type materials incorporating helical π-expanded carbazole(Cz Naph) and 7H-dinaphtho[1,8-bc:1,8-ef]azepine(Az Naph), alongside traditional carbazole, ranging from mono-to tetra-substituted configurations(D_(n)-A). Through systematic investigation of geometric and electronic structures, the number and positioning of multiple donors are confirmed with significant manipulations on charge transfer characteristics and the S_(1) state via steric effects. Density functional theory(DFT) calculations reveal that varying the number of π-extended donors within the acceptor framework produces emission colors from ultraviolet to red, providing a diverse range of emitters. Furthermore, the reduced reorganization energy of S1observed in tetra-substituted Cz and Cz Naph, as well as Mono Az N, indicates lower structural relaxation, highlighting these materials' potential as stable luminescent candidates. This study underscores the importance of diverse composing units in achieving efficient and stable TADF emitters with multiple and hetero-donor configurations.展开更多
Two-dimensional transition metal dichalcogenides(2D TMDCs)have received considerable attention in local strain engineering due to their extraordinary mechanical flexibility,electonic structure,and optical properties.T...Two-dimensional transition metal dichalcogenides(2D TMDCs)have received considerable attention in local strain engineering due to their extraordinary mechanical flexibility,electonic structure,and optical properties.The strain-induced out-of-plane deformations in 2D TMDCs lead to diverse excitonic behaviors and versatile modulations in optical properties,paving the way for the development of advanced quantum technologies,flexible optoelectronic materials,and straintronic devices.Research on local strain engineering on 2D TMDCs has been delved into fabrication techniques,electronic state variations,and quantum optical applications.This review begins by summarizing the state-of-the-art methods for introducing local strain into 2D TMDCs,followed by an exploration of the impact of local strain engineering on optical properties.The intriguing phenomena resulting from local strain,such as exciton funnelling and anti-funnelling,are also discussed.We then shift the focus to the application of locally strained 2D TMDCs as quantum emitters,with various strategies outlined for modulating the properties of TMDC-based quantum emitters.Finally,we discuss the remaining questions in this field and provide an outlook on the future of local strain engineering on 2D TMDCs.展开更多
Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch dr...Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch drip irrigation emitters,focusing on the anti-clogging performance through the experiment,were investigated.The dynamic variations in the clogging characteristics of emitters,specifically were subjected to statistical analysis.The movement mechanism of emitter clogging and discharging sediment was studied.The effects of emitter structure and position factors on emitter clogging were analyzed.The results show that the pressure-compensated emitter exhibits superior anti-clogging perfor-mance,with a service life that is 227.8%greater than that of the labyrinth channel emitter.A single structural factor cannot completely evaluate the anti-clogging performance of emitters.All factors causing emitter clogging should be considered comprehensively.Emitters contain sensitive sediment prone to clogging,however,significant blockage occurs primarily when the sediment content is elevated.The discharge of sediment,denoted as V90,from the emitter is affected by the accumulative effect of clogged sediment.These results may offer valuable insights for the application and advancement of drip irrigation technology.展开更多
Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS...Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS and PPPIS,with hot exciton property are successfully developed.Compared to PPIS,the embedded phenyl bridge in PPPIS is able to effectively increase the overlap of frontier molecular orbitals.In consequence,PPPIS shows higher oscillator strength and significantly enhanced PLQY.PPPIS also achieves better electroluminescence performance in non-doped device,showing deep-blue emission with Commission International de l’Eclairage(CIE)coordinates of(0.153,0.087)and the maximum external quantum efficiency(EQEmax)of 8.5%with minuscule efficiency roll-off.Meanwhile,when PPPIS serves as the host for phosphor PO-01,high-efficiency orange phosphorescent device is obtained with high EQEmax of 29.8%and negligible efficiency roll-off at 1000 cd/m^(2).Further,efficient single-emissive-layer white device is assembled via utilizing PPPIS as a blue emitter as well as the host for PO-01 simultaneously,providing warm-white emission with CIE coordinates of(0.429,0.433)at 1000 cd/m^(2),the forward-viewing EQEmaxof 27.2%and maximum power efficiency(PEmax)of 80.1 lm/W,respectively.Our studies can establish a viable design strategy for deep-blue emitters in high-performance non-doped blue OLEDs and hybrid WOLEDs.展开更多
The paper investigates the escape probability for isotropic emitters near a Kerr black hole.We propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case studies.Thi...The paper investigates the escape probability for isotropic emitters near a Kerr black hole.We propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case studies.This approach is based on studies of the black hole shadow with astrometric observable and can be applied to emitters with an arbitrary 4-velocities and locations,even to the emitters outside of the equatorial plane.We also consider representative examples illustrating how escape probabilities vary with distance,velocity,and inclination angle.Overall,this new approach provides an effective method for studying escape probabilities near Kerr black holes.展开更多
Six-year old apple trees were selected for field experiment.The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards.There were three factors:the buried ...Six-year old apple trees were selected for field experiment.The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards.There were three factors:the buried depth H(25,40,55 cm),the horizontal distance L(30,40,60 cm)between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N(1,2,4).The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency(IWUE)of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75%of the field water capacity.The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28388.17 kg/hm2 and 16.83 kg/m3 in treatment T3,respectively.At the same L and N levels(T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22%and 31.48%,while IWUE is reduced by14.02%and 18.12%compared with T3,respectively.At the same H and N levels(T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level.Especially,when L was 30 cm(T3),the yield and IWUE were the highest.The same L and H levels(T3,T6,and T7)could promote the growth of apple trees when N was 2(T3).Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%.Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.展开更多
Nowadays,the development of trip let-involved materials becomes a hot research topic in solid-state luminescence fields.However,the mechanism of trip let-involved emission still remains some mysteries to conquer.Here,...Nowadays,the development of trip let-involved materials becomes a hot research topic in solid-state luminescence fields.However,the mechanism of trip let-involved emission still remains some mysteries to conquer.Here,we proposed a new concept of excited-state confo rmation capture for the const ructio ns of different types of trip let-involved materials.Firstly,excited-state conformation could be trapped by supramolecular chains in crystal and fo rm a new optimum excited-state structure which is different from that in solution or simple rigid environment,leading to bright thermally activated delayed fluorescence(TADF) emission.Based on excited-state conformation capture methodology,next,we obtained roomtemperature phosphorescence(RTP) by introducing Br atoms for the enhancement of intersystem crossing.It could be concluded from experime ntal results that TADF may originate from aggregate effect while RTP may derive from monomers.Finally,heavy-atom free RTP and ultra RTP were achieved by eliminating aggregate effect.This wo rk could not only exte nd the design methodology of triplet-involved materials but also set clear evidences for the mechanism of triplet-involved emissions.展开更多
Single-photon emitters (SPEs) are one of the key components in quantum information applications. The ideal SPEs emit a single photon or a photon-pair on demand, with high purity and distinguishability. SPEs can also b...Single-photon emitters (SPEs) are one of the key components in quantum information applications. The ideal SPEs emit a single photon or a photon-pair on demand, with high purity and distinguishability. SPEs can also be integrated in photonic circuits for scalable quantum communication and quantum computer systems. Quantum dots made from Ⅲ-Ⅴ compounds such as InGaAs or GaN have been found to be particularly attractive SPE sources due to their well studied optical performance and state of the art industrial flexibility in fabrication and integration. Here, we review the optical and optoelectronic properties and growth methods of general SPEs. Subsequently, a brief summary of the latest advantages in Ⅲ-Ⅴ compound SPEs and the research progress achieved in the past few years will be discussed. We finally describe frontier challenges and conclude with the latest SPE fabrication science and technology that can open new possibilities for quantum information applications.展开更多
Comparing and evaluating the Nationally Determined Contribution(NDC) is an important element in global stocktake in the post-Paris climate negotiations, aimed at closing the emissions gap with the Paris Agreement goal...Comparing and evaluating the Nationally Determined Contribution(NDC) is an important element in global stocktake in the post-Paris climate negotiations, aimed at closing the emissions gap with the Paris Agreement goals. To date, however, there has still been no explicit guideline or method. By applying emissions allowance allocated by 16 schemes as benchmarks, this paper tries to compare and evaluate the NDCs of the top six emitters, which jointly account for about 70% of the world's CO_2 emissions. Results show that the four developed countries' NDCs lack ambition with respect to most allocations under 2℃ and all under 1.5℃, indicating they need to substantially ratchet up their NDCs and lead elevating mitigation. Evaluating cumulative emissions is more likely to clarify the ambition and fairness of China's NDC. If considering cumulative emissions, China's NDC is aligned with the median of cumulative allowances under 2℃ and within the 1.5℃ range. The Paris Agreement invited the Parties to communicate the mid-century low emissions strategies. This paper also tries to explore the mid-century mitigation in the perspective of allocations, which might provide decision-makers with some useful information when envisaging the post-NDC mitigation.展开更多
Various single or multi-modality therapeutic options are available to treat pain of bone metastasis in patients with prostate cancer.Different radionuclides that emitβ-rays such as 153Samarium and 89Strontium and ach...Various single or multi-modality therapeutic options are available to treat pain of bone metastasis in patients with prostate cancer.Different radionuclides that emitβ-rays such as 153Samarium and 89Strontium and achieve palliation are commercially available.In contrast toβ-emitters,223Radium as a a-emitter has a short path-length.The advantage of the a-emitter is thus a highly localized biological effect that is caused by radiation induced DNA double-strand breaks and subsequent cell killing and/or limited effectiveness of cellular repair mechanisms.Due to the limited range of the a-particles the bone surface to red bone marrow dose ratio is also lower for 223Radium which is expressed in a lower myelotoxicity.The a emitter 223Radium dichloride is the first radiopharmaceutical that significantly prolongslife in castrate resistant prostate cancer patients with wide-spread bone metastatic disease.In a phaseⅢ,randomized,double-blind,placebo-controlled study 921patients with castration-resistant prostate cancer and bone metastases were randomly assigned.The analysis confirmed the 223Radium survival benefit compared to the placebo(median,14.9 mo vs 11.3 mo;P<0.001).In addition,the treatment results in pain palliation and thus,improved quality of life and a delay of skeletal related events.At the same time the toxicity profile of223Radium was favourable.Since May 2013,223Radium dichloride(Xofigo?)is approved by the US Food and Drug Administration.展开更多
White organic light-emitting diodes(WOLEDs)show very promising as next-generation light-sources,but achieving high power efficiency(PE)and long operational lifetime remains challenging because of the lack of stable bl...White organic light-emitting diodes(WOLEDs)show very promising as next-generation light-sources,but achieving high power efficiency(PE)and long operational lifetime remains challenging because of the lack of stable blue emitters that can harvest all triplet(T_(1))excitons for light emission.Herein,we propose integrating stable azure multiresonance thermally activated delayed fluorescent(MR-TADF)emitters into tri-color hybrid WOLEDs to tackle these issues.By meticulously selecting MR-TADF emitters and precisely tuning the exciton recombination zone,the optimized tri-color devices based on BCzBN-3B achieve color-stable white light emission with maximum external quantum efficiency(EQE_(max))and maximum PE(PE_(max))of 34.4%and 101.8 Im W^(-1),respectively.Furthermore,the LTgo,defined as the time for the luminance to drop to 90%of its initial value at 1000 cd m^(-2),reaches 761 h.In addition,a hybrid WOLED with deep blue emitter developed using our strategy achieves a high color rendering index of 88 and an EQE_(max) of 30.6%,further demonstrating the versatility and effectiveness of our approach.The record-breaking efficiency and ultra-long lifetime underscore the success of hybrid white-light devices by incorporating robust blue MR-TADF emitters.These advancements open new avenues for commercialization of hybrid WOLEDs,presenting promising solutions for energy-efficient lighting and display technologies.展开更多
Bright single-photon emitters(SPEs)are fundamental components in many quantum applications.However,it is difficult to simultaneously get large Purcell enhancements and quantum yields in metallic nanostructures because...Bright single-photon emitters(SPEs)are fundamental components in many quantum applications.However,it is difficult to simultaneously get large Purcell enhancements and quantum yields in metallic nanostructures because of the huge losses in the metallic nanostructures.Herein,we propose to combine an ultrathin metallic bowtie antenna with a silicon antenna above a metallic substrate to simultaneously get large Purcell enhancements,quantum yields,and collection efficiencies.As a result,the brightness of SPEs in the hybrid nanostructure is greatly increased.Due to the deep subwavelength field confinement(mode size<10 nm)of surface plasmons in the ultrathin metallic film(thickness<4 nm),the Purcell enhancement of the metallic bowtie antenna improves by more than 25 times when the metal thickness decreases from 20 nm to 2 nm.In the hybrid nanostructures by combining an ultrathin metallic bowtie antenna with a silicon antenna,the Purcell enhancement(Fp≈2.6×10^(6))in the hybrid nanostructures is 63 times greater than those(≤4.1×10^(4))in the previous metallic and hybrid nanostructures.Because of the reduced ratio of electromagnetic fields in the ultrathin metallic bowtie antenna when the high-index silicon antenna is under the quasi-BIC state,a high quantum yield(QY≈0.70)is obtained.Moreover,the good radiation directivity of the quasi-BIC(bound state in the continuum)mode of the silicon antenna and the reflection of the metallic substrate result in a high collection efficiency(CE≈0.71).Consequently,the overall enhancement factor of brightness of a SPE in the hybrid nanostructure is EF∗≈Fp×QY×CE≈1.3×10^(6),which is 5.6×10^(2) times greater than those(EF∗≤2.2×103)in the previous metallic and hybrid nanostructures.展开更多
Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes exci...Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes excitation exhibit better performance.In addition to laser cooling and nanoscale thermometry,anti-Stokes excitation can improve the coherence of single-photon sources for advanced quantum technologies.In this review,we follow the recent advances in phononassisted upconversion photoluminescence of quantum emitters and discuss the upconversion mechanisms,applications,and prospects for quantum emitters with anti-Stokes excitation.展开更多
Applications of platinum complexes as phosphorescent emitters in high efficiency organic light-emitting diodes （OLEDs） were shortly discussed in this paper. Key recent studies on highly efficient blue, green, red an...Applications of platinum complexes as phosphorescent emitters in high efficiency organic light-emitting diodes （OLEDs） were shortly discussed in this paper. Key recent studies on highly efficient blue, green, red and white-phosphorescent OLEDs based on Pt complexes are presented in terms of efficiency and color quality.展开更多
Owing to weak light-matter interactions in natural materials,it is difficult to dynamically tune and switch emission polariza-tion states of plasmonic emitters(or antennas)at nanometer scales.Here,by using a control l...Owing to weak light-matter interactions in natural materials,it is difficult to dynamically tune and switch emission polariza-tion states of plasmonic emitters(or antennas)at nanometer scales.Here,by using a control laser beam to induce a bubble(n=1.0)in water(n=1.333)to obtain a large index variation as high as|Δn|=0.333,the emission polarization of an ultra-small plasmonic emitter(~0.4λ^(2))is experimentally switched at nanometer scales.The plasmonic emitter consists of two orthogonal subwavelength metallic nanogroove antennas on a metal surface,and the separation of the two anten-nas is only s_(x)=120 nm.The emission polarization state of the plasmonic emitter is related to the phase difference between the emission light from the two antennas.Because of a large refractive index variation(|Δn|=0.333),the phase difference is greatly changed when a microbubble emerges in water under a low-intensity control laser.As a result,the emission polarization of the ultra-small plasmonic emitter is dynamically switched from an elliptical polarization state to a linear polarization state,and the change of the degree of linear polarization is as high asΔγ≈0.66.展开更多
We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short ...We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short time, and the correlation coefficient RAB is employed to describe the photon pair source quality in a long time limit. The results demonstrate that the coupling single quantum emitters can be considered as a stable photon pair source.展开更多
Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter ...Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.展开更多
Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLED...Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.展开更多
Thermally activated delayed fluorescence(TADF)emitter is a promising organic light-emitting diode(OLED)material due to low cost,wide luminous color gamut and 100%exciton utilization efficiency[1].To achieve high TADF ...Thermally activated delayed fluorescence(TADF)emitter is a promising organic light-emitting diode(OLED)material due to low cost,wide luminous color gamut and 100%exciton utilization efficiency[1].To achieve high TADF performance,a feasible strategy is to construct a twisted donor–acceptor(D–A)unit,decreasing the overlap between the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO),and minimizing the energy gap(∆E_(ST))between the lowest singlet(S_(1))and triplet(T_(1))states[2,3].However,this long-range charge transfer feature is often disadvantageous for achieving high oscillator strengths(f)and radiative transition rates(k_(r))[4](Fig.1(a)).展开更多
Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. A...Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.展开更多
基金financially supported by the National Key Research and Development Program of China (No. 2023YFB3608902)the National Natural Science Foundation of China (Nos. 22275003, 12404460)+3 种基金Key-Area Research and Development Program of Guangdong Province (No. 2019B010924003)Development and Reform Commission of Shenzhen Municipality (No. XMHT20220106002)Guangdong Key Laboratory of Flexible Optoelectronic Materials and Devices, the Foundation for Youth Innovative Talents in Higher Education of Guangdong Province (No. 2023KQNCX094)the Guangdong Basic and Applied Basic Research Foundation (No. 2023A1515111072)。
文摘Multiple donor-acceptor(D-A) combinations represent a promising category of thermally activated delayed fiuorescence(TADF) materials, offering potential for superior efficiency and stability. However, current systems are predominantly composed of limited donor groups, primarily carbazole-based derivatives. In this work, we developed a series of D-A type materials incorporating helical π-expanded carbazole(Cz Naph) and 7H-dinaphtho[1,8-bc:1,8-ef]azepine(Az Naph), alongside traditional carbazole, ranging from mono-to tetra-substituted configurations(D_(n)-A). Through systematic investigation of geometric and electronic structures, the number and positioning of multiple donors are confirmed with significant manipulations on charge transfer characteristics and the S_(1) state via steric effects. Density functional theory(DFT) calculations reveal that varying the number of π-extended donors within the acceptor framework produces emission colors from ultraviolet to red, providing a diverse range of emitters. Furthermore, the reduced reorganization energy of S1observed in tetra-substituted Cz and Cz Naph, as well as Mono Az N, indicates lower structural relaxation, highlighting these materials' potential as stable luminescent candidates. This study underscores the importance of diverse composing units in achieving efficient and stable TADF emitters with multiple and hetero-donor configurations.
基金support from National Natural Science Foundation of China(Grant Nos.62205223)Natural Science Foundation of Guangdong Province(Grant Nos.2023A1515011455)+6 种基金Science and Technology Innovation Commission of Shenzhen(Grant Nos.20231121120748002)support from Guangdong Introducing Innovative and Entrepreneurial Teams(Grant Nos.2019ZT08L101)Natural Science Foundation of Guangdong Province(Grant Nos.2023A1515110091)Science and Technology Innovation Commission of Shenzhen(Grant Nos.JSGGKQTD20221101115701006)support from National Key R&D Program of China(Grant Nos.2021YFA1401100)National Natural Science Foundation of China(Grant Nos.12104317)Scientific Instrument Developing Project of Shenzhen University(Grant Nos.2023YQ003)。
文摘Two-dimensional transition metal dichalcogenides(2D TMDCs)have received considerable attention in local strain engineering due to their extraordinary mechanical flexibility,electonic structure,and optical properties.The strain-induced out-of-plane deformations in 2D TMDCs lead to diverse excitonic behaviors and versatile modulations in optical properties,paving the way for the development of advanced quantum technologies,flexible optoelectronic materials,and straintronic devices.Research on local strain engineering on 2D TMDCs has been delved into fabrication techniques,electronic state variations,and quantum optical applications.This review begins by summarizing the state-of-the-art methods for introducing local strain into 2D TMDCs,followed by an exploration of the impact of local strain engineering on optical properties.The intriguing phenomena resulting from local strain,such as exciton funnelling and anti-funnelling,are also discussed.We then shift the focus to the application of locally strained 2D TMDCs as quantum emitters,with various strategies outlined for modulating the properties of TMDC-based quantum emitters.Finally,we discuss the remaining questions in this field and provide an outlook on the future of local strain engineering on 2D TMDCs.
基金National Natural Science Foundation of China(52269011,52469008)。
文摘Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch drip irrigation emitters,focusing on the anti-clogging performance through the experiment,were investigated.The dynamic variations in the clogging characteristics of emitters,specifically were subjected to statistical analysis.The movement mechanism of emitter clogging and discharging sediment was studied.The effects of emitter structure and position factors on emitter clogging were analyzed.The results show that the pressure-compensated emitter exhibits superior anti-clogging perfor-mance,with a service life that is 227.8%greater than that of the labyrinth channel emitter.A single structural factor cannot completely evaluate the anti-clogging performance of emitters.All factors causing emitter clogging should be considered comprehensively.Emitters contain sensitive sediment prone to clogging,however,significant blockage occurs primarily when the sediment content is elevated.The discharge of sediment,denoted as V90,from the emitter is affected by the accumulative effect of clogged sediment.These results may offer valuable insights for the application and advancement of drip irrigation technology.
基金financial support from National Natural Science Foundation of China(No.22075100)the Jilin Provincial Science and Technology Department(No.20220201082GX)+2 种基金the China Postdoctoral Science Foundation(Nos.2022TQ0111,2023M731267)Sichuan Science and Technology Program(No.2023NSFSC0985)Scientific Research Foundation of Chengdu University of Information Technology(No.KYTZ202174)and the Changsha Automobile Innovation Research Institute。
文摘Deep-blue emitter with high photoluminescence efficiency(PLQY)is highly desirable in ultra-high definition displays and white solid-state lightings.In this work,two deep-blue phenanthro[9,10]imidazole derivatives,PPIS and PPPIS,with hot exciton property are successfully developed.Compared to PPIS,the embedded phenyl bridge in PPPIS is able to effectively increase the overlap of frontier molecular orbitals.In consequence,PPPIS shows higher oscillator strength and significantly enhanced PLQY.PPPIS also achieves better electroluminescence performance in non-doped device,showing deep-blue emission with Commission International de l’Eclairage(CIE)coordinates of(0.153,0.087)and the maximum external quantum efficiency(EQEmax)of 8.5%with minuscule efficiency roll-off.Meanwhile,when PPPIS serves as the host for phosphor PO-01,high-efficiency orange phosphorescent device is obtained with high EQEmax of 29.8%and negligible efficiency roll-off at 1000 cd/m^(2).Further,efficient single-emissive-layer white device is assembled via utilizing PPPIS as a blue emitter as well as the host for PO-01 simultaneously,providing warm-white emission with CIE coordinates of(0.429,0.433)at 1000 cd/m^(2),the forward-viewing EQEmaxof 27.2%and maximum power efficiency(PEmax)of 80.1 lm/W,respectively.Our studies can establish a viable design strategy for deep-blue emitters in high-performance non-doped blue OLEDs and hybrid WOLEDs.
基金supported by the National Key Research and Development Program of China, Grant No. 2020YFC2201502by grants from the National Natural Science Foundation of China (Grant No. 11991052)the Key Research Program of Frontier Sciences, CAS, Grant No. ZDBS-LY-7009
文摘The paper investigates the escape probability for isotropic emitters near a Kerr black hole.We propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case studies.This approach is based on studies of the black hole shadow with astrometric observable and can be applied to emitters with an arbitrary 4-velocities and locations,even to the emitters outside of the equatorial plane.We also consider representative examples illustrating how escape probabilities vary with distance,velocity,and inclination angle.Overall,this new approach provides an effective method for studying escape probabilities near Kerr black holes.
基金Supporting founds:National Key R&D Program(2016YFC0400204)Natural Science Foundation of China(51479161,51279157,51779205)。
文摘Six-year old apple trees were selected for field experiment.The objective of this study was to obtain the reasonable arrangement of surge-root irrigation emitters in apple orchards.There were three factors:the buried depth H(25,40,55 cm),the horizontal distance L(30,40,60 cm)between the emitters and the trunk of the experimental tree,and the number of the irrigation emitters N(1,2,4).The effect of the arrangement of surge-root irrigation emitters on the growth,yield and irrigation water use efficiency(IWUE)of apple trees were studied in Northern Shaanxi where the irrigation quota takes 60%-75%of the field water capacity.The results showed that the arrangement of emitters for surge-root irrigation had a significant effect on apple tree yield and IWUE,especially,the yield and IWUE reached 28388.17 kg/hm2 and 16.83 kg/m3 in treatment T3,respectively.At the same L and N levels(T1,T2,and T3),the yield and IWUE in treatment T3 were the highest,and the yields in treatments T1 and T2 were decreased by 26.22%and 31.48%,while IWUE is reduced by14.02%and 18.12%compared with T3,respectively.At the same H and N levels(T3,T4,and T5),the yield and IWUE of apple trees were decreased with increasing L level.Especially,when L was 30 cm(T3),the yield and IWUE were the highest.The same L and H levels(T3,T6,and T7)could promote the growth of apple trees when N was 2(T3).Compared with treatment T3,it was found that the increment of new shoots was decreased by 8.07%-18.71%,and the fruit diameter was decreased by 5.41%-9.11%.Therefore,two emitters should be arranged symmetrically on both sides of an apple tree,each was buried at a 40 cm depth and 30 cm away from the trunk of the tree to effectively improve the yield and IWUE of the apple tree in mountainous areas in Northern Shaanxi.
基金This work was supported by the National Natural Science Foundation of China(No.51773077).
文摘Nowadays,the development of trip let-involved materials becomes a hot research topic in solid-state luminescence fields.However,the mechanism of trip let-involved emission still remains some mysteries to conquer.Here,we proposed a new concept of excited-state confo rmation capture for the const ructio ns of different types of trip let-involved materials.Firstly,excited-state conformation could be trapped by supramolecular chains in crystal and fo rm a new optimum excited-state structure which is different from that in solution or simple rigid environment,leading to bright thermally activated delayed fluorescence(TADF) emission.Based on excited-state conformation capture methodology,next,we obtained roomtemperature phosphorescence(RTP) by introducing Br atoms for the enhancement of intersystem crossing.It could be concluded from experime ntal results that TADF may originate from aggregate effect while RTP may derive from monomers.Finally,heavy-atom free RTP and ultra RTP were achieved by eliminating aggregate effect.This wo rk could not only exte nd the design methodology of triplet-involved materials but also set clear evidences for the mechanism of triplet-involved emissions.
文摘Single-photon emitters (SPEs) are one of the key components in quantum information applications. The ideal SPEs emit a single photon or a photon-pair on demand, with high purity and distinguishability. SPEs can also be integrated in photonic circuits for scalable quantum communication and quantum computer systems. Quantum dots made from Ⅲ-Ⅴ compounds such as InGaAs or GaN have been found to be particularly attractive SPE sources due to their well studied optical performance and state of the art industrial flexibility in fabrication and integration. Here, we review the optical and optoelectronic properties and growth methods of general SPEs. Subsequently, a brief summary of the latest advantages in Ⅲ-Ⅴ compound SPEs and the research progress achieved in the past few years will be discussed. We finally describe frontier challenges and conclude with the latest SPE fabrication science and technology that can open new possibilities for quantum information applications.
基金supported by the National Natural Science Foundation of China "Assessment,enhancement and impact of the Intended Nationally Determined Contributions in the context of the Paris Agreement"[Grant number:71703167]the National Key Research and Development Program of the Ministry of Science and Technology "Carbon emissions reduction potentials and economic costs of major countries"[Grant number:2017YFA0605302]the Science Foundation of China University of Petroleum,Beijing "China's energy system transformation toward the 2℃goal:a perspective of carbon budgets"[Grant number:2462016YJRC023]
文摘Comparing and evaluating the Nationally Determined Contribution(NDC) is an important element in global stocktake in the post-Paris climate negotiations, aimed at closing the emissions gap with the Paris Agreement goals. To date, however, there has still been no explicit guideline or method. By applying emissions allowance allocated by 16 schemes as benchmarks, this paper tries to compare and evaluate the NDCs of the top six emitters, which jointly account for about 70% of the world's CO_2 emissions. Results show that the four developed countries' NDCs lack ambition with respect to most allocations under 2℃ and all under 1.5℃, indicating they need to substantially ratchet up their NDCs and lead elevating mitigation. Evaluating cumulative emissions is more likely to clarify the ambition and fairness of China's NDC. If considering cumulative emissions, China's NDC is aligned with the median of cumulative allowances under 2℃ and within the 1.5℃ range. The Paris Agreement invited the Parties to communicate the mid-century low emissions strategies. This paper also tries to explore the mid-century mitigation in the perspective of allocations, which might provide decision-makers with some useful information when envisaging the post-NDC mitigation.
文摘Various single or multi-modality therapeutic options are available to treat pain of bone metastasis in patients with prostate cancer.Different radionuclides that emitβ-rays such as 153Samarium and 89Strontium and achieve palliation are commercially available.In contrast toβ-emitters,223Radium as a a-emitter has a short path-length.The advantage of the a-emitter is thus a highly localized biological effect that is caused by radiation induced DNA double-strand breaks and subsequent cell killing and/or limited effectiveness of cellular repair mechanisms.Due to the limited range of the a-particles the bone surface to red bone marrow dose ratio is also lower for 223Radium which is expressed in a lower myelotoxicity.The a emitter 223Radium dichloride is the first radiopharmaceutical that significantly prolongslife in castrate resistant prostate cancer patients with wide-spread bone metastatic disease.In a phaseⅢ,randomized,double-blind,placebo-controlled study 921patients with castration-resistant prostate cancer and bone metastases were randomly assigned.The analysis confirmed the 223Radium survival benefit compared to the placebo(median,14.9 mo vs 11.3 mo;P<0.001).In addition,the treatment results in pain palliation and thus,improved quality of life and a delay of skeletal related events.At the same time the toxicity profile of223Radium was favourable.Since May 2013,223Radium dichloride(Xofigo?)is approved by the US Food and Drug Administration.
基金support from the National Natural ScienceFoundationof China(52373192 and52130308)Research Team Cultivation Program of Shenzhen University(Grant No.2023DFT004)+1 种基金Natural Science Foundation of Guangdong Province(2024A1515030199)the Shenzhen Science and Technology Program(ZDSYS20210623091813040 and 20220810164838001)。
文摘White organic light-emitting diodes(WOLEDs)show very promising as next-generation light-sources,but achieving high power efficiency(PE)and long operational lifetime remains challenging because of the lack of stable blue emitters that can harvest all triplet(T_(1))excitons for light emission.Herein,we propose integrating stable azure multiresonance thermally activated delayed fluorescent(MR-TADF)emitters into tri-color hybrid WOLEDs to tackle these issues.By meticulously selecting MR-TADF emitters and precisely tuning the exciton recombination zone,the optimized tri-color devices based on BCzBN-3B achieve color-stable white light emission with maximum external quantum efficiency(EQE_(max))and maximum PE(PE_(max))of 34.4%and 101.8 Im W^(-1),respectively.Furthermore,the LTgo,defined as the time for the luminance to drop to 90%of its initial value at 1000 cd m^(-2),reaches 761 h.In addition,a hybrid WOLED with deep blue emitter developed using our strategy achieves a high color rendering index of 88 and an EQE_(max) of 30.6%,further demonstrating the versatility and effectiveness of our approach.The record-breaking efficiency and ultra-long lifetime underscore the success of hybrid white-light devices by incorporating robust blue MR-TADF emitters.These advancements open new avenues for commercialization of hybrid WOLEDs,presenting promising solutions for energy-efficient lighting and display technologies.
基金the National Key Research and Development Program of China(Grant Nos.2018YFA0704401,2017YFF0206103,and 2016YFA0203500)the National Natural Science Foundation of China(Grant Nos.61922002,91850103,11674014,61475005,11527901,11525414,and 91850111)the Beijing Natural Science Foundation,China(Grant No.Z180015).
文摘Bright single-photon emitters(SPEs)are fundamental components in many quantum applications.However,it is difficult to simultaneously get large Purcell enhancements and quantum yields in metallic nanostructures because of the huge losses in the metallic nanostructures.Herein,we propose to combine an ultrathin metallic bowtie antenna with a silicon antenna above a metallic substrate to simultaneously get large Purcell enhancements,quantum yields,and collection efficiencies.As a result,the brightness of SPEs in the hybrid nanostructure is greatly increased.Due to the deep subwavelength field confinement(mode size<10 nm)of surface plasmons in the ultrathin metallic film(thickness<4 nm),the Purcell enhancement of the metallic bowtie antenna improves by more than 25 times when the metal thickness decreases from 20 nm to 2 nm.In the hybrid nanostructures by combining an ultrathin metallic bowtie antenna with a silicon antenna,the Purcell enhancement(Fp≈2.6×10^(6))in the hybrid nanostructures is 63 times greater than those(≤4.1×10^(4))in the previous metallic and hybrid nanostructures.Because of the reduced ratio of electromagnetic fields in the ultrathin metallic bowtie antenna when the high-index silicon antenna is under the quasi-BIC state,a high quantum yield(QY≈0.70)is obtained.Moreover,the good radiation directivity of the quasi-BIC(bound state in the continuum)mode of the silicon antenna and the reflection of the metallic substrate result in a high collection efficiency(CE≈0.71).Consequently,the overall enhancement factor of brightness of a SPE in the hybrid nanostructure is EF∗≈Fp×QY×CE≈1.3×10^(6),which is 5.6×10^(2) times greater than those(EF∗≤2.2×103)in the previous metallic and hybrid nanostructures.
基金the National Key Research and Development Program of China(2017YFA0303401)the CAS Interdisciplinary Innovation Team,the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB28000000)the NSFC(12074371,U21A2070,and 62027816)。
文摘Quantum emitters are widely used in quantum networks,quantum information processing,and quantum sensing due to their excellent optical properties.Compared with Stokes excitation,quantum emitters under anti-Stokes excitation exhibit better performance.In addition to laser cooling and nanoscale thermometry,anti-Stokes excitation can improve the coherence of single-photon sources for advanced quantum technologies.In this review,we follow the recent advances in phononassisted upconversion photoluminescence of quantum emitters and discuss the upconversion mechanisms,applications,and prospects for quantum emitters with anti-Stokes excitation.
基金supported by the Development Foundation for Electronic and Information Industry(2010),the Science and Technology Commission of Shanghai Municipality(Grant No.10DZ1140502)the Mechatronics Engineering Innovation Group Project from Shanghai Education Commissionthe Key Laboratory of Advanced Display and System Applications(Shanghai University),Ministry of Education,China(Grant No.P201004)
文摘Applications of platinum complexes as phosphorescent emitters in high efficiency organic light-emitting diodes （OLEDs） were shortly discussed in this paper. Key recent studies on highly efficient blue, green, red and white-phosphorescent OLEDs based on Pt complexes are presented in terms of efficiency and color quality.
基金supported by the National Key Research and Development Program of China(2018YFA0704401)the Beijing Natural Science Foundation(Z180015)the National Natural Science Foundation of China(61922002 and 91850103).
文摘Owing to weak light-matter interactions in natural materials,it is difficult to dynamically tune and switch emission polariza-tion states of plasmonic emitters(or antennas)at nanometer scales.Here,by using a control laser beam to induce a bubble(n=1.0)in water(n=1.333)to obtain a large index variation as high as|Δn|=0.333,the emission polarization of an ultra-small plasmonic emitter(~0.4λ^(2))is experimentally switched at nanometer scales.The plasmonic emitter consists of two orthogonal subwavelength metallic nanogroove antennas on a metal surface,and the separation of the two anten-nas is only s_(x)=120 nm.The emission polarization state of the plasmonic emitter is related to the phase difference between the emission light from the two antennas.Because of a large refractive index variation(|Δn|=0.333),the phase difference is greatly changed when a microbubble emerges in water under a low-intensity control laser.As a result,the emission polarization of the ultra-small plasmonic emitter is dynamically switched from an elliptical polarization state to a linear polarization state,and the change of the degree of linear polarization is as high asΔγ≈0.66.
基金Project supported by the National Natural Science Foundation of China(Grand Nos.91021009,21073110,and 11374191)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2013AQ020)+2 种基金the Postdoctoral Science Foundation of China(Grant No.2013M531584)the Doctoral Program of Higher Education of China(Grant Nos.20130131110005 and 20130131120006)the Taishan Scholarship Project of Shandong Province,China
文摘We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short time, and the correlation coefficient RAB is employed to describe the photon pair source quality in a long time limit. The results demonstrate that the coupling single quantum emitters can be considered as a stable photon pair source.
基金supported by the National Natural Science Foundation of China (No.50379053,50609029,50779068)
文摘Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.
基金supported by the National Natural Science Foundation of China (Nos.51773029,52073040 and 51821002)the Fundamental Research Funds for the Central Universities (No.ZYGX2016Z010)the International Cooperation and Exchange Project of Science and Technology Department of Sichuan Province (No.2019YFH0057)。
文摘Thermally activated delayed fluorescent(TADF) materials capable of efficient solution-processed nondoped organic light-emitting diodes(OLEDs) are of important and practical significance for further development of OLEDs. In this work, a new electron-donating segment, 2,7-di(9 H-carbazol-9-yl)-9,9-dimethyl-9,10-dihydroacridine(2 Cz-DMAC), was designed to develop solution-processable non-doped TADF emitters. 2 Cz-DMAC can not only simultaneously increase the solubility of compounds and suppress harmful aggregation-caused quenching, but also efficiently broaden the delocalization of the highest occupied molecular orbital and promote the reverse intersystem crossing process. Three new TADF emitters, 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)dibenzo[b,d]thiophene 5,5-dioxide(2 Cz-DMAC-BTB), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)-9 H-thioxanthen-9-one(2 Cz-DMAC-TXO), 2-(2,7-di(9 H-carbazol-9-yl)-9,9-dimethylacridin-10(9 H)-yl)thianthrene 5,5,10,10-tetraoxide(2 Cz-DMAC-TTR), were developed by using 2 Cz-DMAC segment as the electron-donor. As anticipated, the solution-processed non-doped OLEDs employing 2 Cz-DMAC-BTB, 2 Cz-DMAC-TXO and 2 CzDMAC-TTR as the emitters respectively exhibited green, orange and red emissions with maximum external quantum efficiencies of 14.0%, 6.6% and 2.9%. These results successfully demonstrate the feasibility and convenience of developing efficient solution-processable non-doped TADF emitters based on 2 CzDMAC segment.
基金This work was supported by the National Natural Science Foundation of China(21975119)L.Ding thanks the open research fund of Songshan Lake Materials Laboratory(2021SLABFK02)the National Natural Science Foundation of China(51922032 and 21961160720).
文摘Thermally activated delayed fluorescence(TADF)emitter is a promising organic light-emitting diode(OLED)material due to low cost,wide luminous color gamut and 100%exciton utilization efficiency[1].To achieve high TADF performance,a feasible strategy is to construct a twisted donor–acceptor(D–A)unit,decreasing the overlap between the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO),and minimizing the energy gap(∆E_(ST))between the lowest singlet(S_(1))and triplet(T_(1))states[2,3].However,this long-range charge transfer feature is often disadvantageous for achieving high oscillator strengths(f)and radiative transition rates(k_(r))[4](Fig.1(a)).
文摘Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.
