Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of t...Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.展开更多
Green energy generation is an indispensable task to concurrently resolve fossil fuel depletion and environmental issues to align with the global goals of achieving carbon neutrality.Photocatalysis,a process that trans...Green energy generation is an indispensable task to concurrently resolve fossil fuel depletion and environmental issues to align with the global goals of achieving carbon neutrality.Photocatalysis,a process that transforms solar energy into clean fuels through a photocatalyst,represents a felicitous direction toward sustainability.Eco-rich metal-free graphitic carbon nitride(g-C_(3)N_(4))is profiled as an attractive photocatalyst due to its fascinating properties,including excellent chemical and thermal stability,moderate band gap,visible light-active nature,and ease of fabrication.Nonetheless,the shortcomings of g-C_(3)N_(4)include fast charge recombination and limited surface-active sites,which adversely affect photocatalytic reactions.Among the modification strategies,point-to-face contact engineering of 2D g-C_(3)N_(4)with 0D nanomaterials represents an innovative and promising synergy owing to several intriguing attributes such as the high specific surface area,short effective charge-transfer pathways,and quantum confinement effects.This review introduces recent advances achieved in experimental and computational studies on the interfacial design of 0D nanostructures on 2D g-C_(3)N_(4)in the construction of point-to-face heterojunction interfaces.Notably,0D materials such as metals,metal oxides,metal sulfides,metal selenides,metal phosphides,and nonmetals on g-C_(3)N_(4)with different charge-transfer mechanisms are systematically discussed along with controllable synthesis strategies.The applications of 0D/2D g-C_(3)N_(4)-based photocatalysts are focused on solar-to-energy conversion via the hydrogen evolution reaction,the CO_(2)reduction reaction,and the N2 reduction reaction to evaluate the photocatalyst activity and elucidate reaction pathways.Finally,future perspectives for developing high-efficiency 0D/2D photocatalysts are proposed to explore potential emerging carbon nitride allotropes,large-scale production,machine learning integration,and multidisciplinary advances for technological breakthroughs.展开更多
We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> crystals. This current study utilizes the relationship between the vibroni...We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> crystals. This current study utilizes the relationship between the vibronic coupling and the degree of charge-transfer to explain the differences of Surface Enhanced Raman Scattering (SERS) enhancements. Our study shows a direct correlation between the degree of charge-transfer and vibronic coupling. This relationship suggests that charge-transfer between the N-719 dye and TiO<sub>2</sub> due to vibronic coupling plays a fundamental role in SERS enhancements. Furthermore, this study shows a strong dependence of the enhancements of the N-719 dye molecular modes to that of the surface modes. This indicates that the mechanism that governs the enhancements of the surface modes in TiO<sub>2</sub> crystals most likely also dictates the enhancements of the N-719 dyes.展开更多
A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite ...A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite film and there is an interaction between H 4SiW 12O 40 and the organic substrate. The composite film showed a reversible photochromism. Under UV irradiation, the composite film turns blue and charge transfer occurs by oxidation of R-NH + 3 and reduction of SiW 12O 4- 40. When the irradiated samples are placed in air and sheltered from the light, they change back to their original color, and recover again when being exposed to UV light.展开更多
Fast-charging is highly demanded for applications requiring short charging time.However,fast-charging triggers serious problems,leading to decline in charge acceptance and energy efficiency,accelerated capacity degrad...Fast-charging is highly demanded for applications requiring short charging time.However,fast-charging triggers serious problems,leading to decline in charge acceptance and energy efficiency,accelerated capacity degradation,and safety risk.In this work,a three-electrode coin cell with a Li metal reference electrode is designed to individually record the potential of two electrodes,and measure the impedance of each electrode by using a power-optimized graphite-LiNi0.80Co0.15Al0.05O2 electrode couple.It is shown that regardless of the state-of-charge the Li-ion cell's impedance is contributed predominantly by the cathode,and that the cathode's impedance is dominated by the charge-transfer resistance.In consistence with the impedance results,polarization of the Li-ion cell is dominated by the cathode.It is surprised to find that no Li plating occurs on the graphite anode even if the charging rate is increased to 10 C(1 C=1.30 mA cm^−2).The results of this work indicate that low overall impedance with a high cathode-to-anode impedance ratio is the key to enabling safe fast-charging,and that fast-charging Li-ion batteries without Li plating on the graphite anode is possible if the cathode and graphite anode are optimistically engineered.展开更多
Donor-Acceptor(D-A)alignment is considered a productive strategy to improve the charge separation efficiency of covalent organic frameworks(COFs)and enhance the charge-transfer yield(CTY)of COFs.Moreover,organic molec...Donor-Acceptor(D-A)alignment is considered a productive strategy to improve the charge separation efficiency of covalent organic frameworks(COFs)and enhance the charge-transfer yield(CTY)of COFs.Moreover,organic molecules containing heteroatoms can produce coordination interaction with PbI2 of perovskite precursor to affect the crystallization process,thereby impeding the decomposition and improving the stability of perovskite materials.Herein,a thiazolo[5,4-d]thiazole(TZ)-based D-A type COF_(TPDA-TZDA) was designed and synthesized from N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-benzenediamine(TPDA)and 4,4′-(thiazolo[5,4-d]thiazole-2,5-diyl)dibenzaldehyde(TZDA).Upon incorporation into the FAPbI3 layer,COF_(TPDA-TZDA) not only restrained the perovskite defects and enhanced the grain size of perovskite films through the coordination effect of the N atoms of TZDA but also ameliorated the charge transport within the perovskite film,which was the benefit of the D-A structure of COF_(TPDA-TZDA).As a result,incorporation of COF_(TPDA-TZDA) into the perovskite solar cells(PSCs)led to a remarkable power conversion efficiency(PCE)of up to 23.51%.Furthermore,even after being stored in high relative humidity(RH≈60%)for 480 h,these PSCs maintained over 90.55%of their original PCE.This work sets the foundation for the development of highly efficient and stable PSCs by utilizing TZ-based D-A type COFs.展开更多
While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-pla...While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.展开更多
Single-phase Co-doped TiO2（CoxZil_xO2） nanoparticles（NPs） synthesized via a simple sol-hydrothermal me- thod were used as surface-enhanced Raman scattering（SERS） substrates. Interestingly, it was found that SERS...Single-phase Co-doped TiO2（CoxZil_xO2） nanoparticles（NPs） synthesized via a simple sol-hydrothermal me- thod were used as surface-enhanced Raman scattering（SERS） substrates. Interestingly, it was found that SERS signals were enhanced greatly compared to those of pure TiO2 nanoparticles when an amount of Co2＋ ions were doped into the TiO2 lattice. Detailed results clearly show that Co element as Co2＋ was incorporated into the TiO2 lattice and the defects were created due to the substitution of Coz＋ ions for the Ti4＋ ions. The Co2＋ doping increases the defect concentration of CoxTil_xO2 NPs. An amount of defects is beneficial to the charge-transfer so as to increase the SERS activities. A possi- ble mechanism of charge-transfer from CoxTi1-xO2 NPs to molecules was then briefly discussed.展开更多
The donor-n-conjugated-acceptor （D-n-A） structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two ...The donor-n-conjugated-acceptor （D-n-A） structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two examples of D-^-A structures capable to finely modulate the excited state properties and arrangement of energy levels, TPA-AN-BP and CZP-AN-BP, which possess the same acceptor and n-bridge but different donor. The investigation of their photophysical properties and DFT calculation revealed that the D-n-A structure with proper donor, n-bridge and acceptor can result in separation of frontier molecular orbitals on the corresponding donor and acceptor with an obvious overlap on the n-bridge, resulting in a hybridized local and charge-transfer （HLCT） excited state with high photoluminescent （PL） efficiencies. Meanwhile, their singlet and triplet states are arranged on corresponding moie- ties with large energy gap between T2 and T1, and a small energy gap between S1 and T2, which favor the reverse intersystem crossing （RISC） from high-lying triplet levels to singlet levels. As a result, the sky-blue emission non-doped OLED based on the TPA-AN-BP reached maximum external quantum efficiency （EQE） of 4.39% and a high exciton utilization efficiency （EUE） of 77%. This study demonstrates a new strategy to construct highly effi- cient OLED materials.展开更多
To investigate whether the arrangement of componentsin multi-composite photocatalysts may affect their photocatalytic properties,due to different charge-transfer routes,two ternary-nanocomposite photocatalysts with di...To investigate whether the arrangement of componentsin multi-composite photocatalysts may affect their photocatalytic properties,due to different charge-transfer routes,two ternary-nanocomposite photocatalysts with different component arrangements,comprising N-doped carbon quantum dots(NCQDs),g-C3N4(CN),and Bi2WO6(BWO)(hereafter referred to as NCQDs/CN/BWO),were developed,and the photocatalytic degradation of model hazardous vapors under visible-light illumination was investigated.Type I NCQDs/CN/BWO,which was developed by the combination of NCQDs/BWO and CN,exhibited photocatalytic ability superior to that of type II NCQDs/CN/BWO,which was developed by the combination of CN/BWO and NCQDs;the superior photocatalytic ability corresponded to the dual properties of NCQDs:charge mediation and upconversion photoluminescence.Moreover,the photocatalytic ability of NCQDs/CN/BWO was greater than those of the reference catalysts;in addition,this photocatalyst exhibited outstanding photochemical stability.Additionally,the effects of CN/(BWO+CN)weight ratio of the CN/BWO dual nanocomposites and the NCQDs/(BWO+CN+NCQDs)weight percentage of NCQDs/CN/BWO ternary nanocomposites on the pollutant removal efficiency were investigated.The plausible mechanisms over the two NCQDs/CN/BWO photocatalysts for the degradation of hazardous vapors were discussed.The component arrangement approach proposed herein afforded a technique toward the perceptive development of novel multi-component heterostructures for the photocatalytic degradation of hazardous vapors.展开更多
Multiferroic charge-transfer crystals have drawn significant interest due to their simultaneous dipolar and spin ordering. Numerous theoretical and experimental studies have shown that the molecular stacking between d...Multiferroic charge-transfer crystals have drawn significant interest due to their simultaneous dipolar and spin ordering. Numerous theoretical and experimental studies have shown that the molecular stacking between donor and acceptor complexes plays an important role in tuning charge-transfer enabled multifunctionality. Herein, we show that the charge-transfer interactions can be controlled by the segregated stack, consisting of polythiophene donor- and fuUerene acceptor-based all-conjugated block copolymers. Room temperature magnetic field effects, ferroelectricity, and anisotropic magnetism are observed in charge-transfer crystals, which can be further controlled by photoexcitation and charge doping. Furthermore, the charge-transfer segregated stack crystals demonstrate external stimuli controlled polarization and magnetization, which opens up their multifunctional applications for all-organic multiferroics.展开更多
Cross sections of electron-loss in H（1s）＋ H（1s） collisions and total collisional destruction of H（2s） in H（1s） 4- H（2s） collisions are calculatted by four-body classical-trajectory Monte Caylo （CTMC） meth...Cross sections of electron-loss in H（1s）＋ H（1s） collisions and total collisional destruction of H（2s） in H（1s） 4- H（2s） collisions are calculatted by four-body classical-trajectory Monte Caylo （CTMC） method and compared with previous theoretical and experimental data over the energy range of 4-100 keV. For the former a good agreement is obtained within different four-body CTMC calculations, and for the incident energy Ep 〉 10 keV, comparison with the experimental data shows a better agreement than the results calculated by the impact parameter approx- imation. For the latter, our theory predicts the correct experimental behaviour, and the discrepancies between our results and experimental ones are less than 30%. Based on the successive comparison with experiments, the cross sections for excitation to H（2p）, single- and double-ionization and H- formation in H（2s）＋H（2s） collisions are calculated in the energy range of 4-100 keV for the first time, and compared with those in H（1s）＋H（1s） and H（1s）＋U（2s） collisions.展开更多
Energy-transfer-mediated synthetic reactions play vital roles in the production of high-value-added organics,where the longlived exciton harvesting is an essential precondition for the process.However,for semiconducto...Energy-transfer-mediated synthetic reactions play vital roles in the production of high-value-added organics,where the longlived exciton harvesting is an essential precondition for the process.However,for semiconductors with strong excitonic effects like conjugated polymers,their predominant Frenkel exciton with a short lifetime in the unified framework gives rise to low efficiency photocatalysis.Herein,we propose the boosting of the charge-transfer exciton with a long-lived state by introducing spatially separated electron and hole regions.By taking polymeric carbon nitride(PCN)as a prototype,we demonstrate that sulfur doping leads to the formation of electron donor and acceptor motifs in the tri-s-triazinebased backbone,which would accommodate long-lived excitonic states with remarkable charge-transfer characteristics.The extraordinary long-lived charge-transfer exciton harvesting endows sulfur-doped PCN with high-efficiency photocatalytic performance in 1O2 generation and selective oxidation of organic sulfides.This work provides a brand new perspective for designing advanced photocatalysts for energy-transfer-mediated sunlight utilization.展开更多
A number of electron-rich heterocycles are studied as potential reagents for visual colorimetric detection of FOX-7 due to colored charge-transfer complexes formation.The obtained results suggest that pyrrole and pyri...A number of electron-rich heterocycles are studied as potential reagents for visual colorimetric detection of FOX-7 due to colored charge-transfer complexes formation.The obtained results suggest that pyrrole and pyrimidine derivatives can form such complexes playing the role of electron donors despite a low electrophilicity of FOX-7.Density functional theory calculations,as well as quantum theory of atoms in molecules analysis,suggest stacking binding mode as the most preferable one with the binding energy of about 21-36 kJ/mol.All the complexes demonstrate a clear single charge-transfer absorption band in the visible region and the expected colors of the complexes are varying from violet and blue to red and orange.The calculations of the crystalline state of the studied complexes indicate high lattice energies,which are higher than that of pure FOX-7 and are close to the recently reported hydrogen-bonded complex of FOX-7 with 1,10-phenanthroline.Additional analysis of the studied charge-transfer complexes using properties based on density difference grids clearly suggests the acceptor role of FOX-7 in the complexes.This analysis can be effectively applied to identify the nature of other possible complexes of FOX-7,in which its role is unclear because of the specific reactivity,namely,both weak electrophilic and nucleophilic properties at the same time.展开更多
基金supported by the National Natural Science Foundation of China(21334002,51303057,51373054,91233113)the National Basic Research Program of China(2013CB834705,2014CB643504,2015CB655003)+1 种基金the Fundamental Research Funds for the Central Universities(2013ZZ0001)the Introduced Innovative R&D Team of Guangdong(201101C0105067115)
文摘Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.
基金Ministry of Higher Education,Malaysia,Grant/Award Number:FRGS/1/2020/TK0/XMU/02/1Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2021A1515111019+1 种基金Hengyuan International Sdn.Bhd.,Grant/Award Number:EENG/0003Xiamen University Malaysia,Grant/Award Numbers:IENG/0038,ICOE/0001,XMUMRF/2019-C3/IENG/0013,XMUMRF/2021-C8/IENG/0041。
文摘Green energy generation is an indispensable task to concurrently resolve fossil fuel depletion and environmental issues to align with the global goals of achieving carbon neutrality.Photocatalysis,a process that transforms solar energy into clean fuels through a photocatalyst,represents a felicitous direction toward sustainability.Eco-rich metal-free graphitic carbon nitride(g-C_(3)N_(4))is profiled as an attractive photocatalyst due to its fascinating properties,including excellent chemical and thermal stability,moderate band gap,visible light-active nature,and ease of fabrication.Nonetheless,the shortcomings of g-C_(3)N_(4)include fast charge recombination and limited surface-active sites,which adversely affect photocatalytic reactions.Among the modification strategies,point-to-face contact engineering of 2D g-C_(3)N_(4)with 0D nanomaterials represents an innovative and promising synergy owing to several intriguing attributes such as the high specific surface area,short effective charge-transfer pathways,and quantum confinement effects.This review introduces recent advances achieved in experimental and computational studies on the interfacial design of 0D nanostructures on 2D g-C_(3)N_(4)in the construction of point-to-face heterojunction interfaces.Notably,0D materials such as metals,metal oxides,metal sulfides,metal selenides,metal phosphides,and nonmetals on g-C_(3)N_(4)with different charge-transfer mechanisms are systematically discussed along with controllable synthesis strategies.The applications of 0D/2D g-C_(3)N_(4)-based photocatalysts are focused on solar-to-energy conversion via the hydrogen evolution reaction,the CO_(2)reduction reaction,and the N2 reduction reaction to evaluate the photocatalyst activity and elucidate reaction pathways.Finally,future perspectives for developing high-efficiency 0D/2D photocatalysts are proposed to explore potential emerging carbon nitride allotropes,large-scale production,machine learning integration,and multidisciplinary advances for technological breakthroughs.
文摘We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> crystals. This current study utilizes the relationship between the vibronic coupling and the degree of charge-transfer to explain the differences of Surface Enhanced Raman Scattering (SERS) enhancements. Our study shows a direct correlation between the degree of charge-transfer and vibronic coupling. This relationship suggests that charge-transfer between the N-719 dye and TiO<sub>2</sub> due to vibronic coupling plays a fundamental role in SERS enhancements. Furthermore, this study shows a strong dependence of the enhancements of the N-719 dye molecular modes to that of the surface modes. This indicates that the mechanism that governs the enhancements of the surface modes in TiO<sub>2</sub> crystals most likely also dictates the enhancements of the N-719 dyes.
文摘A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite film and there is an interaction between H 4SiW 12O 40 and the organic substrate. The composite film showed a reversible photochromism. Under UV irradiation, the composite film turns blue and charge transfer occurs by oxidation of R-NH + 3 and reduction of SiW 12O 4- 40. When the irradiated samples are placed in air and sheltered from the light, they change back to their original color, and recover again when being exposed to UV light.
基金Funding information Army Research Laboratory,Grant/Award Number:N/A
文摘Fast-charging is highly demanded for applications requiring short charging time.However,fast-charging triggers serious problems,leading to decline in charge acceptance and energy efficiency,accelerated capacity degradation,and safety risk.In this work,a three-electrode coin cell with a Li metal reference electrode is designed to individually record the potential of two electrodes,and measure the impedance of each electrode by using a power-optimized graphite-LiNi0.80Co0.15Al0.05O2 electrode couple.It is shown that regardless of the state-of-charge the Li-ion cell's impedance is contributed predominantly by the cathode,and that the cathode's impedance is dominated by the charge-transfer resistance.In consistence with the impedance results,polarization of the Li-ion cell is dominated by the cathode.It is surprised to find that no Li plating occurs on the graphite anode even if the charging rate is increased to 10 C(1 C=1.30 mA cm^−2).The results of this work indicate that low overall impedance with a high cathode-to-anode impedance ratio is the key to enabling safe fast-charging,and that fast-charging Li-ion batteries without Li plating on the graphite anode is possible if the cathode and graphite anode are optimistically engineered.
基金supported by the National Natural Science Foundation of China (grant nos.22375070 and 22288101)the Jilin Province Science and Technology Development Plan (grant nos.20220101048JC and 20210101112JC)the 111 Project the Ministry of Education of China (grant no.B17020).
文摘Donor-Acceptor(D-A)alignment is considered a productive strategy to improve the charge separation efficiency of covalent organic frameworks(COFs)and enhance the charge-transfer yield(CTY)of COFs.Moreover,organic molecules containing heteroatoms can produce coordination interaction with PbI2 of perovskite precursor to affect the crystallization process,thereby impeding the decomposition and improving the stability of perovskite materials.Herein,a thiazolo[5,4-d]thiazole(TZ)-based D-A type COF_(TPDA-TZDA) was designed and synthesized from N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-benzenediamine(TPDA)and 4,4′-(thiazolo[5,4-d]thiazole-2,5-diyl)dibenzaldehyde(TZDA).Upon incorporation into the FAPbI3 layer,COF_(TPDA-TZDA) not only restrained the perovskite defects and enhanced the grain size of perovskite films through the coordination effect of the N atoms of TZDA but also ameliorated the charge transport within the perovskite film,which was the benefit of the D-A structure of COF_(TPDA-TZDA).As a result,incorporation of COF_(TPDA-TZDA) into the perovskite solar cells(PSCs)led to a remarkable power conversion efficiency(PCE)of up to 23.51%.Furthermore,even after being stored in high relative humidity(RH≈60%)for 480 h,these PSCs maintained over 90.55%of their original PCE.This work sets the foundation for the development of highly efficient and stable PSCs by utilizing TZ-based D-A type COFs.
基金the Natural Science Foundation of China(No.22175191)Y.C.thanks the financial support from CAS-Croucher Funding Scheme for Joint Laboratories and Beijing Municipal Science&Technology Commission(No.Z211100007921020).
文摘While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.
基金Supported by the National Natural Science Foundation of China（Nos.21273091, 21221063）, the Specialized Research Fund for the Doctoral Program of Higher Education, China（No.20110061110017）, the Program of Introducing Talents of Discipline to Chinese Universities（No.B06009）, the Postdoctoral Science Foundation, China（No.2013M530974） and the Development Program of the Science and Technology of Jilin Province, China（No.20110338）.
文摘Single-phase Co-doped TiO2（CoxZil_xO2） nanoparticles（NPs） synthesized via a simple sol-hydrothermal me- thod were used as surface-enhanced Raman scattering（SERS） substrates. Interestingly, it was found that SERS signals were enhanced greatly compared to those of pure TiO2 nanoparticles when an amount of Co2＋ ions were doped into the TiO2 lattice. Detailed results clearly show that Co element as Co2＋ was incorporated into the TiO2 lattice and the defects were created due to the substitution of Coz＋ ions for the Ti4＋ ions. The Co2＋ doping increases the defect concentration of CoxTil_xO2 NPs. An amount of defects is beneficial to the charge-transfer so as to increase the SERS activities. A possi- ble mechanism of charge-transfer from CoxTi1-xO2 NPs to molecules was then briefly discussed.
文摘The donor-n-conjugated-acceptor （D-n-A） structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two examples of D-^-A structures capable to finely modulate the excited state properties and arrangement of energy levels, TPA-AN-BP and CZP-AN-BP, which possess the same acceptor and n-bridge but different donor. The investigation of their photophysical properties and DFT calculation revealed that the D-n-A structure with proper donor, n-bridge and acceptor can result in separation of frontier molecular orbitals on the corresponding donor and acceptor with an obvious overlap on the n-bridge, resulting in a hybridized local and charge-transfer （HLCT） excited state with high photoluminescent （PL） efficiencies. Meanwhile, their singlet and triplet states are arranged on corresponding moie- ties with large energy gap between T2 and T1, and a small energy gap between S1 and T2, which favor the reverse intersystem crossing （RISC） from high-lying triplet levels to singlet levels. As a result, the sky-blue emission non-doped OLED based on the TPA-AN-BP reached maximum external quantum efficiency （EQE） of 4.39% and a high exciton utilization efficiency （EUE） of 77%. This study demonstrates a new strategy to construct highly effi- cient OLED materials.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(Nos.2016R1A2B4009122 and 2017R1A4A1015628).
文摘To investigate whether the arrangement of componentsin multi-composite photocatalysts may affect their photocatalytic properties,due to different charge-transfer routes,two ternary-nanocomposite photocatalysts with different component arrangements,comprising N-doped carbon quantum dots(NCQDs),g-C3N4(CN),and Bi2WO6(BWO)(hereafter referred to as NCQDs/CN/BWO),were developed,and the photocatalytic degradation of model hazardous vapors under visible-light illumination was investigated.Type I NCQDs/CN/BWO,which was developed by the combination of NCQDs/BWO and CN,exhibited photocatalytic ability superior to that of type II NCQDs/CN/BWO,which was developed by the combination of CN/BWO and NCQDs;the superior photocatalytic ability corresponded to the dual properties of NCQDs:charge mediation and upconversion photoluminescence.Moreover,the photocatalytic ability of NCQDs/CN/BWO was greater than those of the reference catalysts;in addition,this photocatalyst exhibited outstanding photochemical stability.Additionally,the effects of CN/(BWO+CN)weight ratio of the CN/BWO dual nanocomposites and the NCQDs/(BWO+CN+NCQDs)weight percentage of NCQDs/CN/BWO ternary nanocomposites on the pollutant removal efficiency were investigated.The plausible mechanisms over the two NCQDs/CN/BWO photocatalysts for the degradation of hazardous vapors were discussed.The component arrangement approach proposed herein afforded a technique toward the perceptive development of novel multi-component heterostructures for the photocatalytic degradation of hazardous vapors.
文摘Multiferroic charge-transfer crystals have drawn significant interest due to their simultaneous dipolar and spin ordering. Numerous theoretical and experimental studies have shown that the molecular stacking between donor and acceptor complexes plays an important role in tuning charge-transfer enabled multifunctionality. Herein, we show that the charge-transfer interactions can be controlled by the segregated stack, consisting of polythiophene donor- and fuUerene acceptor-based all-conjugated block copolymers. Room temperature magnetic field effects, ferroelectricity, and anisotropic magnetism are observed in charge-transfer crystals, which can be further controlled by photoexcitation and charge doping. Furthermore, the charge-transfer segregated stack crystals demonstrate external stimuli controlled polarization and magnetization, which opens up their multifunctional applications for all-organic multiferroics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10434100, 10574018 and 10574020.
文摘Cross sections of electron-loss in H（1s）＋ H（1s） collisions and total collisional destruction of H（2s） in H（1s） 4- H（2s） collisions are calculatted by four-body classical-trajectory Monte Caylo （CTMC） method and compared with previous theoretical and experimental data over the energy range of 4-100 keV. For the former a good agreement is obtained within different four-body CTMC calculations, and for the incident energy Ep 〉 10 keV, comparison with the experimental data shows a better agreement than the results calculated by the impact parameter approx- imation. For the latter, our theory predicts the correct experimental behaviour, and the discrepancies between our results and experimental ones are less than 30%. Based on the successive comparison with experiments, the cross sections for excitation to H（2p）, single- and double-ionization and H- formation in H（2s）＋H（2s） collisions are calculated in the energy range of 4-100 keV for the first time, and compared with those in H（1s）＋H（1s） and H（1s）＋U（2s） collisions.
基金the National Key R&D Program of China(2022YFA1502903,2021YFA1501502,2019YFA0210004)the National Natural Science Foundation of China(22275179,92163105,T2122004,21890754,U2032212,U2032160)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)the Youth Innovation Promotion Association of CAS(Y2021123)the Fundamental Research Funds for the Central Universities(WK2060000039)the University Synergy Innovation Program of Anhui Province(GXXT-2020-005).
文摘Energy-transfer-mediated synthetic reactions play vital roles in the production of high-value-added organics,where the longlived exciton harvesting is an essential precondition for the process.However,for semiconductors with strong excitonic effects like conjugated polymers,their predominant Frenkel exciton with a short lifetime in the unified framework gives rise to low efficiency photocatalysis.Herein,we propose the boosting of the charge-transfer exciton with a long-lived state by introducing spatially separated electron and hole regions.By taking polymeric carbon nitride(PCN)as a prototype,we demonstrate that sulfur doping leads to the formation of electron donor and acceptor motifs in the tri-s-triazinebased backbone,which would accommodate long-lived excitonic states with remarkable charge-transfer characteristics.The extraordinary long-lived charge-transfer exciton harvesting endows sulfur-doped PCN with high-efficiency photocatalytic performance in 1O2 generation and selective oxidation of organic sulfides.This work provides a brand new perspective for designing advanced photocatalysts for energy-transfer-mediated sunlight utilization.
基金supported by the Ministry of Education and Science of Ukraine(No.0122U000760)。
文摘A number of electron-rich heterocycles are studied as potential reagents for visual colorimetric detection of FOX-7 due to colored charge-transfer complexes formation.The obtained results suggest that pyrrole and pyrimidine derivatives can form such complexes playing the role of electron donors despite a low electrophilicity of FOX-7.Density functional theory calculations,as well as quantum theory of atoms in molecules analysis,suggest stacking binding mode as the most preferable one with the binding energy of about 21-36 kJ/mol.All the complexes demonstrate a clear single charge-transfer absorption band in the visible region and the expected colors of the complexes are varying from violet and blue to red and orange.The calculations of the crystalline state of the studied complexes indicate high lattice energies,which are higher than that of pure FOX-7 and are close to the recently reported hydrogen-bonded complex of FOX-7 with 1,10-phenanthroline.Additional analysis of the studied charge-transfer complexes using properties based on density difference grids clearly suggests the acceptor role of FOX-7 in the complexes.This analysis can be effectively applied to identify the nature of other possible complexes of FOX-7,in which its role is unclear because of the specific reactivity,namely,both weak electrophilic and nucleophilic properties at the same time.
