Metal-organic frameworks(MOFs),which are self-assembled porous coordination materials,have garnered considerable attention in the fields of optoelectronics,photovoltaic,photochemistry,and photocatalysis due to their d...Metal-organic frameworks(MOFs),which are self-assembled porous coordination materials,have garnered considerable attention in the fields of optoelectronics,photovoltaic,photochemistry,and photocatalysis due to their diverse structures and excellent tunability.However,the performance of MOF-based optoelectronic applications currently falls short of the industry benchmark.To enhance the performance of MOF materials,it is imperative to undertake comprehensive investigations aimed at gaining a deeper understanding of photophysics and sequentially optimizing properties related to photocarrier transport,recombination,interaction,and transfer.By utilizing femtosecond laser pulses to excite MOFs,time-resolved optical spectroscopy offers a means to observe and characterize these ultrafast microscopic processes.This approach adds the time coordinate as a novel dimension for comprehending the interaction between light and MOFs.Accordingly,this review provides a comprehensive overview of the recent advancements in the photophysics of MOFs and additionally outlines potential avenues for exploring the time domain in the investigation of MOFs.展开更多
A series of new silicon-containing poly（p-arylene vinylene）s （PAVs） with anthracene units in the main chain were synthesized by hydrosilylation reaction. The introduction of organosilicon units improved the solubi...A series of new silicon-containing poly（p-arylene vinylene）s （PAVs） with anthracene units in the main chain were synthesized by hydrosilylation reaction. The introduction of organosilicon units improved the solubility of the polymers, and the π-π conjugation of polymeric chains was interrupted. These polymers behaved as blue-green light emitters with their fluorescence maximum at 447-499 nm and quantum yields in the range of 0.28-0.30 in solution.展开更多
We have designed and synthesized a new B-and N-embedded asymmetric heteroleptic phosphorescent iridium(Ⅲ)complex IrBNacac with ambipolar characteristics.The X-ray diffraction technique shows that the two B-and N-embe...We have designed and synthesized a new B-and N-embedded asymmetric heteroleptic phosphorescent iridium(Ⅲ)complex IrBNacac with ambipolar characteristics.The X-ray diffraction technique shows that the two B-and N-embeddedπ-conjugation units in the complex exhibit good planarity and induce richπ-πinteractions in the crystal state.More importantly,it exhibits an effective red emission(623 nm)in the thin film state with a very narrow full width at half maximum(FWHM=50 nm,0.158 eV),even narrower than that of model complexes(53 nm,0.162 eV for IrBBacac and 62 nm,0.224 eV for IrNNacac).DFT calculation shows that the lowest excited triplet state(T_(1))of the complex IrBNacac exhibits richer excited state characteristics than those of the model complexes,including a charge transfer transition from the N-embedded ligand to the B-embedded ligand(^(3)LLCT)and a metal-to-ligand charge transfer transition(^(3)MLCT),along with an intraligand charge transfer(^(3)ILCT).Considering the good photophysical properties and solubility,the red-emitting complex IrBNacac was used as the emitting layer of a solution-processed OLED device and showed good maximum external quantum efficiency(EQE)(4.9%)peaking at 625 nm with the CIE coordinates(0.64,0.35),accompanied by a low turn-on voltage.This research provides an important strategy for the design of narrowband red-emitting phosphorescent iridium complexes and their optoelectronic applications.展开更多
Three closo-o-carborane-functionalised pyrene compounds(1CB,2CB,and 4CB)were synthesised and fully characterised.The molecular structures of all compounds exhibited perpendicularity between the C-C bond of the o-carbo...Three closo-o-carborane-functionalised pyrene compounds(1CB,2CB,and 4CB)were synthesised and fully characterised.The molecular structures of all compounds exhibited perpendicularity between the C-C bond of the o-carborane and the pyrene groups.The three compounds displayed major absorption bands assignable to π-π*transitions within the pyrene group,as well as weak intramolecular chargetransfer(ICT)transitions between the o-carborane units and the pyrene moieties.While 1CB and 4CB displayed strong ICT-based emissions involving the o-carborane moiety(λ_(em)=500-700 nm)in THF at 298 K,2CB showed less intense LE-based emissions centred at λ_(em)=407 nm.Although the PL spectra of all compounds demonstrated enhanced ICT-based emission via inhibition of C-C bond variance within the o-carborane in rigid states(THF at 77 K and films),the quantum efficiency of 2CB in films(Φ_(em)=5%)did not significantly increase compared to that in THF at 298 K,while the values for 1CB and 4CB in films were dramatically enhanced to 75%and 62%,respectively.The radiative decay constants of each ICTbased emission showed that non-radiative decay processes were significantly larger for 2CB than in 1CB and 4CB.The relative energies of the various S0 conformations as the dihedral angle between the o-carborane cage and pyrene unit was changed indicated that the o-carborane cages in 2CB could rotate more easily than those in 1CB and 4CB.Furthermore,the involvement of the o-carborane moiety in the LUMO level of 2CB was significantly affected by this dihedral angle.These results suggest that the free rotation of the o-carborane cage of 2CB interrupted its ICT transitions,with experimental and theoretical findings confirming that large structural variations around the o-carborane cage for 2CB also induced ICT-based non-radiative decay processes associated with the o-carborane,further blocking the ICT transition itself.展开更多
The main difficulties hindering development of a deep-blue phosphorescent cyclometalated Ir(III)complex are insufficient colour purity,i.e.,failure to achieve ideal Commission Internationale de L’Eclairage(CIE)coordi...The main difficulties hindering development of a deep-blue phosphorescent cyclometalated Ir(III)complex are insufficient colour purity,i.e.,failure to achieve ideal Commission Internationale de L’Eclairage(CIE)coordinates of(0.14,0.09),and insufficient emission efficiency and stability.The latter problem is due to the highly energetic and hot excited states of these complexes,which yield faster decomposition.Therefore,control of the excited-state properties of cyclometalated Ir(III)complexes through systematic chemical modification of the ligands is being extensively investigated,with the aim of developing efficient and stable blue phosphorescent materials.The most common strategies towards achievement of a blue phosphorescent cyclometalated Ir(III)complex involve(1)substitution of electronwithdrawing F atoms at the cyclometalating ligands that stabilise the HOMO orbitals and(2)use of a heteroleptic system with electron-rich ancillary ligands bearing a 5-membered ring heterocycle to increase the LUMO energy level.However,the C-F bonds on the cyclometalating ligands have been found to be inherently unstable during device operation;thus,other types of electron-withdrawing groups(e.g.,the cyano,trifluoromethyl,and sulfonyl groups)have been applied.Along with phosphorescence colour tuning to blue,the influence of the ligand structure on the photoluminescence quantum yield(PLQY)is also being intensively investigated.Two major PLQY lowering mechanisms for blue emissive Ir(III)complexes have been identified:(1)the vibronic-coupled non-radiative decay process and(2)crossing from the emissive state to an upper non-emissive ^(3)MC excited state.To enhance the PLQY,mechanism(1)can be suppressed by employing rigid ligand frameworks to restrict intramolecular motion,whereas mechanism(2)can be prevented by destabilising the ^(3)MC state using strongσdonor ligands such as N-heterocyclic carbenes.This review summarises the fundamental photophysics of cyclometalated Ir(III)complexes and surveys design strategies for efficient blue phosphorescent Ir(III)complexes,to provide a guide for future research in this field.展开更多
In this work,we explore the excited states of three different[Ru(4,4’-BTFMB)_(2)(L)]^(2+)complexes(C1:L=bpy(2,2’-bipyridine);C2:L=phen(1,10-phenantroline);and C3:L=TAP(1,4,5,8-tetraazaphenanthrene)),aiming to invest...In this work,we explore the excited states of three different[Ru(4,4’-BTFMB)_(2)(L)]^(2+)complexes(C1:L=bpy(2,2’-bipyridine);C2:L=phen(1,10-phenantroline);and C3:L=TAP(1,4,5,8-tetraazaphenanthrene)),aiming to investigate the ligand effects on their photophysical and photochemical properties and also to evaluate their suitability as photosensitizers(PS)for photodynamic therapy(PDT).Compound C3 is a new theoretical proposition for which we have observed a significant lowering in the HOMO and LUMO energies,which can be interpreted as an extra stabilization of the complex,a highly desirable feature for a PS candidate.Also,the low-lying excited states showed a shift in the MLCT transition nature from dRu!π*btfmb to dRu!π*tap,confirming that the presence of a more electronegative atom in the third ligand lowers the energy of the orbitals due to a more effectiveπ-backbonding.Furthermore,the investigation of the excited state reactions has shown a dual character possibility for the three complexes,being thermodynamically favorable for photosensitizing molecular oxygen through energy transfer and oxidizing guanosine-monophosphate through electron transfer.Complex C3 presented the best reaction freeenergy profile,indicating that this new compound is most suitable for use as a photosensitizer in PDT.展开更多
Hypocrellins are novel photosensitizers from China, which are demonstrated to have significant anti-tumor and anti-virus activity and to be potential photo-dynamic therapy (PDT) agents. As compared with hemato-porphyr...Hypocrellins are novel photosensitizers from China, which are demonstrated to have significant anti-tumor and anti-virus activity and to be potential photo-dynamic therapy (PDT) agents. As compared with hemato-porphyrin, the only approved photosensitizer, hypocrellins have several advantages, such as easy preparation and easy purification, high triplet quantum yield, high singlet-oxygen quantum yield, high phototoxicity but low dark toxicity, and rapid clearance from normal issues. This article reviews briefly the photophysics, photochemistry and photobiology of hypocrellins on the basis of the domestic and international research results.展开更多
Understanding the structure-property relationships in polycyclic conjugated hydrocarbons(PCHs)is crucial in controlling their electronic properties and developing new optically functional materials.Aromaticity is a fu...Understanding the structure-property relationships in polycyclic conjugated hydrocarbons(PCHs)is crucial in controlling their electronic properties and developing new optically functional materials.Aromaticity is a fundamentally important and intriguing property of numerous organic chemical structures and has stimulated a myriad of experimental and theoretical investigations.Exploiting aromaticity rules for the rational design of optoelectronic materials with the desired photophysical characteristics is a challenging yet fascinating task.Herein we present an in-depth computational and spectroscopic study on the structure-property relationships of dinaphthopentalenes(DNPs).Results highlight that the different fusion patterns between 4nπand 4n+2πunits endow these PCHs with the tunable aromaticity in the ground state/excited state,which leads to the diverse electronic structures and consequently the distinctive excited state photophysics.Accordingly,we propose a combined aromaticity design strategy for rationally modulating and tailoring electronic and optical properties of PCH skeletons.These outcomes not only present a full picture of the excited state dynamics of the DNP system and afford a new class of efficient singlet fission-active materials but also provide some basic guidelines for exploiting aromaticity rules to design and develop new optical function materials.展开更多
A series of poly（p-phenylenevinylene）s （PPVs） with good solubility were synthesized from thermal elimination of precursor poly（2,5-didodecyloxy-p-phenylenevinylene） at different temperature via Wessling method. ...A series of poly（p-phenylenevinylene）s （PPVs） with good solubility were synthesized from thermal elimination of precursor poly（2,5-didodecyloxy-p-phenylenevinylene） at different temperature via Wessling method. The polymer photophysics were influenced by the thermal elimination condition, which was consistent with NMR and IR characterizations. The additional absorption peak at longer wavelength and the red-shifted emission maximum both in solution and in film, for PPVs obtained at high elimination temperature, indicated the existence of longer conjugated blocks in these systems. The emission maximum for drop-cast film （436 nm） for PPV obtained under 200 ℃ （PPV200） was 16 nm blue shifted to the spin-coated films （452 nm） or 29 nm to the solution （465 nm）. The SEM study showed drop-cast film had the morphology of isolated conjugated particles in the matrix while blurry linear structure was found for spin-coated film, which was consistent with the photophysics. The discussion about this difference was carried out based on the consideration of the flexibility of the polymer chains and different conjugated length of PPV in different states.展开更多
The fluorescence spectra of N--salicylidene-p-(N,N--dimethylamino)aniline have beeninvestigated in various solvents. Three kinds of fluorescence have been found in the solutionsof various concentrations. They are the ...The fluorescence spectra of N--salicylidene-p-(N,N--dimethylamino)aniline have beeninvestigated in various solvents. Three kinds of fluorescence have been found in the solutionsof various concentrations. They are the excited intermediate (EI) which is formed when theproton transfer has occurred but essentially retains the geometry of the enol tautomer, theexciplex (EX) which consists of a ground monomer and an excited state intermediate and theexcited dimer (ED) which is caused by ground state aggregate. The fluorescence lifetimesof the fluorophores have been measured in tetrahydrofuran (THF). Luminescent mechanismhas been discussed based on the fluorescence spectra and the kinetic data of the compound.展开更多
9-Fluorenylidenemalononitrile (FDCN) or 1,1 diphenyl 2,2 dicyanoethylene (DPCN) reacted with 10 methyl 9,10 dihydroacridine (AcrH 2) under irradiation ( λ >320 nm) to give couping products. In order t...9-Fluorenylidenemalononitrile (FDCN) or 1,1 diphenyl 2,2 dicyanoethylene (DPCN) reacted with 10 methyl 9,10 dihydroacridine (AcrH 2) under irradiation ( λ >320 nm) to give couping products. In order to gain further insight into the mechanism of the photo induced reaction, the photophysics of the reactions of FDCN or DPCN with AcrH 2 have been investigated by using UV vis spectroscopy, fluorescence spectroscopy, excitation spectroscopy and time resolved fluorescence spectroscopy, respectively. The results show that FDCN or DPCN interacts with AcrH 2 in the ground states to form a charge transfer complex, which further reacts to give the coupling product upon irradiation.展开更多
The quenching processes of the excited singlet state of pyrene by triphenylamine,diphenyl- amine and N,N-dibenzylaniline in various solvents at room and lower temperature have been stu- died with both static state flu...The quenching processes of the excited singlet state of pyrene by triphenylamine,diphenyl- amine and N,N-dibenzylaniline in various solvents at room and lower temperature have been stu- died with both static state fluorescence spectroscopy and fluorescence lifetime techniques.On the basis of experimental data,a preliminary quenching mechanism has been discussed.The geome- trical configuration models of the exciplexes formed between the excited pyrene and aromatic ami- nes in nonpolar solvents were proposed.展开更多
Azulene-fused acenes demonstrate enhanced stability,unique aromaticity,and distinctive photophysical properties,rendering them significant in organic electronics.In the present study,we report a new type of nonalterna...Azulene-fused acenes demonstrate enhanced stability,unique aromaticity,and distinctive photophysical properties,rendering them significant in organic electronics.In the present study,we report a new type of nonalternant analogue of pentacene incorporating a non-terminal azulene unit.Aromaticity analyses reveal that the five-membered rings in this analogue exhibit antiaromatic.The extensive conjugated aryl substituents on the acene’s side shift the HOMO distributions from the naphthyl ring and metallacycle to the aryl groups,thereby narrowing the HOMO-LUMO energy gap and enhancing absorptions in the low-energy regions.Furthermore,these fused acenes readily react with base rather than acid,resulting in reversible base/acid stimuli responsiveness.展开更多
Green-emitting iridium(Ⅲ)complexes were synthesised using chlorobridged dimer(ppy)_(2)Ir_(2)Cl_(2)(ppy)_(2),3-hydroxy-2-methyl-γ-pyranone,2-ethyl-3-hydroxy-4-pyranone,and 5-hydroxy-2-(hydroxymethyl)-1,4-pyranone as ...Green-emitting iridium(Ⅲ)complexes were synthesised using chlorobridged dimer(ppy)_(2)Ir_(2)Cl_(2)(ppy)_(2),3-hydroxy-2-methyl-γ-pyranone,2-ethyl-3-hydroxy-4-pyranone,and 5-hydroxy-2-(hydroxymethyl)-1,4-pyranone as the auxiliary ligand.The structure of the target product was characterised by nuclear magnetic resonance spectroscopy(~1H-NMR),infrared spectroscopy(IR)and mass spectrometry(MS),and its thermal stability,photophysical properties and electrochemical properties were investigated.The results show that the decomposition temperatures of Ir1,Ir2 and Ir3 are 349,292 and 200℃,respectively.The maximum emission wavelength of Ir1,Ir2 and Ir3 dissolved in dichloromethane is 491 nm.The HOMO energy level of Ir1,Ir2 and Ir3 are 5.39,-5.38,and-5.30 eV.The LUMO energy levels are-2.86,-2.85,and-2.80 eV,respectively.展开更多
A series of poly（aryleneethynylene）s containing dibenzosilole unit has been synthesized by palladium-catalyzed Sonogashira cross-coupling reactions with 2,7-diethynyl-9,9-dihexyl-3,6-dimethoxy-9H-dibenzosilole （4）...A series of poly（aryleneethynylene）s containing dibenzosilole unit has been synthesized by palladium-catalyzed Sonogashira cross-coupling reactions with 2,7-diethynyl-9,9-dihexyl-3,6-dimethoxy-9H-dibenzosilole （4） as the key monomer. Their photophysical properties in solution were investigated. All of the polymers showed intense fluorescence with high quantum efficiencies.展开更多
Organic color-tunable phosphorescent materials depend upon multiple emission centers to achieve colortunable phosphorescence with changes in excitation wavelength,temperature,time,and other external factors.Organic co...Organic color-tunable phosphorescent materials depend upon multiple emission centers to achieve colortunable phosphorescence with changes in excitation wavelength,temperature,time,and other external factors.Organic color-tunable phosphorescent materials are becoming increasingly popular due to their potential applications in anticounterfeiting,encryption and sensing.This brief review focuses on the formation of multiple emission centers in organic color-tunable phosphorescent materials and how to ensure that these multiple emission centers can simultaneously emit.In the future,materials with a large color tunable ranges,increased efficiency,and relatively long lives will be developed.展开更多
A novel Ru（Ⅱ） complex [（bpy）2Ru（PBC）]（PF6）2 （PBC = N-[4-（9-carbazole）butyl]-2-（2-pyridyl）benzimidazole） has been synthesized and verified by 1↑H NMR, elemental analysis and X-ray crystallography. The c...A novel Ru（Ⅱ） complex [（bpy）2Ru（PBC）]（PF6）2 （PBC = N-[4-（9-carbazole）butyl]-2-（2-pyridyl）benzimidazole） has been synthesized and verified by 1↑H NMR, elemental analysis and X-ray crystallography. The crystal （C48H40F12N8P2Ru, Mr = 1119.89） belongs to the triclinic system, space group P1, with a = 13.128（4）, b = 13.814（4）, c = 14.184（4） A, α = 84.112（6）, β = 88.473（6）, γ = 78.196（6）°, Z = 2, V = 2504.6（13）A^3, Dc = 1.485 g/cm^3, F（000） = 1132, R = 0.0750 and wR = 0.1896. The Ru atom adopts a distorted-octahedral coordination geometry with the bond distances and bond angles falling in normal ranges. The complex shows an intense metal-to-ligand charge transfer （1MLCT） （dπ（Ru） →π＊（L）） transition （ε ~1.2×10^4 dm^3mol^-1cm^-1） at 457 nm in the UV-Vis absorption spectrum and a strong red phosphorescence at 632 nm in the CH3CN solution at ambient temperature. An efficient intramolecular energy transfer process from the carbazole unit to the [（bpy）2Ru（PB）]^2＋ emissive center exists by selective optical-simulation. Its electrochemical behavior shows multiplicate redox processes based on the metal center, the grafting carbazole moiety and the 2-（2-pyridyl）benzimidazole unit.展开更多
Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to ...Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to the unclear relationship between the non-conjugated structure and TSI properties.Herein,the TSI in diphenylmethane is manipulated by breaking its symmetric structures and changing the isolated subunits.Finally,the CL wavelength and efficiency of diphenylmethane are successfully regulated at the aggregate state.展开更多
Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on ...Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on the DPP moiety. The polymers were found to have designed chemical structures via structural characterizations in comparison with three monomers. The molecular weight measurement further demonstrated the formation of polymers with polydispersity index around 2, consistent with the polycondensation nature of the polymerization based on Sonogashira coupling. Both polymers could dissolve in many organic solvents, and the one with long alkyl side group on DPP moiety had better solubility. Photophysical investigation showed that both polymers had typical absorption/emission of conjugated polymers, and varying the solvent did not have large influence. Compared with other polar solvents, toluene reduced the quantum yield of fluorescence of the polymers, especially for the one with long alkyl pedant group, accompanying with slight red-shift in absorption/emission. The difference in the absorption/emission wavelengths between the polymers was similar to that between the corresponding monomers. Adding water into the THF solution of polymers reduced the emission intensity but no redshift was observed. Discussion about the structure-property relationships was carried out in detail.展开更多
Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar cells.Copper phthalocyanine(CuPc)is a typical electron acceptor.In this work,the triplet exciton...Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar cells.Copper phthalocyanine(CuPc)is a typical electron acceptor.In this work,the triplet exciton lifetime is prolonged by altering the molecular stacking pattern of the CuPc film.For CuPc thin films,the excited state decays are mainly determined by the triplet-triplet annihilation process.The ultrafast transient absorption measurements indicate that the primary annihilation mechanism is one-dimensional exciton diffusion collision destruction.The decay kinetics show a clearly time-dependent annihilation rate constant withγ∝t^(-1/2).Annihilation rate constants are determined to beγ0=(2.87±0.02)×10^(-20)cm^(3)·s^(-1/2)and(1.42±0.02)×10^(-20)cm^(3)·s^(-1/2)for upright and lyingdown configurations,respectively.Compared to the CuPc thin film with an upright configuration,the thin film with a lying-down configuration shows longer exciton lifetime and higher absorbance,which are beneficial to organic solar cells.The results in this work have important implications on the design and mechanistic understanding of organic optoelectronic devices.展开更多
基金Project supported by the Science Challenge Project(Grant No.TZ2018001)the National Natural Science Foundation of China(Grant Nos.11872058 and 21802036)the Project of State Key Laboratory of Environment-friendly Energy Materials,and Southwest University of Science and Technology(Grant No.21fksy07)。
文摘Metal-organic frameworks(MOFs),which are self-assembled porous coordination materials,have garnered considerable attention in the fields of optoelectronics,photovoltaic,photochemistry,and photocatalysis due to their diverse structures and excellent tunability.However,the performance of MOF-based optoelectronic applications currently falls short of the industry benchmark.To enhance the performance of MOF materials,it is imperative to undertake comprehensive investigations aimed at gaining a deeper understanding of photophysics and sequentially optimizing properties related to photocarrier transport,recombination,interaction,and transfer.By utilizing femtosecond laser pulses to excite MOFs,time-resolved optical spectroscopy offers a means to observe and characterize these ultrafast microscopic processes.This approach adds the time coordinate as a novel dimension for comprehending the interaction between light and MOFs.Accordingly,this review provides a comprehensive overview of the recent advancements in the photophysics of MOFs and additionally outlines potential avenues for exploring the time domain in the investigation of MOFs.
基金supported by the National Natural Science Foundation of China(Nos.50673094 and 20774102)
文摘A series of new silicon-containing poly（p-arylene vinylene）s （PAVs） with anthracene units in the main chain were synthesized by hydrosilylation reaction. The introduction of organosilicon units improved the solubility of the polymers, and the π-π conjugation of polymeric chains was interrupted. These polymers behaved as blue-green light emitters with their fluorescence maximum at 447-499 nm and quantum yields in the range of 0.28-0.30 in solution.
基金financial support from the National Natural Science Foundation of China(22171109 and 22001097)the Natural Science Foundation of Jiangsu Province of China(BK20201003)+1 种基金the Postdoctoral Research Foundation of China(2021M701657)the Shenzhen Science and Technology Program(KQTD20170330110107046).
文摘We have designed and synthesized a new B-and N-embedded asymmetric heteroleptic phosphorescent iridium(Ⅲ)complex IrBNacac with ambipolar characteristics.The X-ray diffraction technique shows that the two B-and N-embeddedπ-conjugation units in the complex exhibit good planarity and induce richπ-πinteractions in the crystal state.More importantly,it exhibits an effective red emission(623 nm)in the thin film state with a very narrow full width at half maximum(FWHM=50 nm,0.158 eV),even narrower than that of model complexes(53 nm,0.162 eV for IrBBacac and 62 nm,0.224 eV for IrNNacac).DFT calculation shows that the lowest excited triplet state(T_(1))of the complex IrBNacac exhibits richer excited state characteristics than those of the model complexes,including a charge transfer transition from the N-embedded ligand to the B-embedded ligand(^(3)LLCT)and a metal-to-ligand charge transfer transition(^(3)MLCT),along with an intraligand charge transfer(^(3)ILCT).Considering the good photophysical properties and solubility,the red-emitting complex IrBNacac was used as the emitting layer of a solution-processed OLED device and showed good maximum external quantum efficiency(EQE)(4.9%)peaking at 625 nm with the CIE coordinates(0.64,0.35),accompanied by a low turn-on voltage.This research provides an important strategy for the design of narrowband red-emitting phosphorescent iridium complexes and their optoelectronic applications.
基金supported by the National Research Foundation of Korea(NRF)grant(2019R1A2C1009969 for M.H.Park,2020R1I1A1A01073381 for J.H.LeeNRF-2020R1A2C1006400 and NRF-2016M3A7B4909246 for K.M.Lee)funded by the Ministry of Science and ICT,and the Ministry of Education.
文摘Three closo-o-carborane-functionalised pyrene compounds(1CB,2CB,and 4CB)were synthesised and fully characterised.The molecular structures of all compounds exhibited perpendicularity between the C-C bond of the o-carborane and the pyrene groups.The three compounds displayed major absorption bands assignable to π-π*transitions within the pyrene group,as well as weak intramolecular chargetransfer(ICT)transitions between the o-carborane units and the pyrene moieties.While 1CB and 4CB displayed strong ICT-based emissions involving the o-carborane moiety(λ_(em)=500-700 nm)in THF at 298 K,2CB showed less intense LE-based emissions centred at λ_(em)=407 nm.Although the PL spectra of all compounds demonstrated enhanced ICT-based emission via inhibition of C-C bond variance within the o-carborane in rigid states(THF at 77 K and films),the quantum efficiency of 2CB in films(Φ_(em)=5%)did not significantly increase compared to that in THF at 298 K,while the values for 1CB and 4CB in films were dramatically enhanced to 75%and 62%,respectively.The radiative decay constants of each ICTbased emission showed that non-radiative decay processes were significantly larger for 2CB than in 1CB and 4CB.The relative energies of the various S0 conformations as the dihedral angle between the o-carborane cage and pyrene unit was changed indicated that the o-carborane cages in 2CB could rotate more easily than those in 1CB and 4CB.Furthermore,the involvement of the o-carborane moiety in the LUMO level of 2CB was significantly affected by this dihedral angle.These results suggest that the free rotation of the o-carborane cage of 2CB interrupted its ICT transitions,with experimental and theoretical findings confirming that large structural variations around the o-carborane cage for 2CB also induced ICT-based non-radiative decay processes associated with the o-carborane,further blocking the ICT transition itself.
基金supported by the National Research Foundation of Korea(2019R1F1A1058578).
文摘The main difficulties hindering development of a deep-blue phosphorescent cyclometalated Ir(III)complex are insufficient colour purity,i.e.,failure to achieve ideal Commission Internationale de L’Eclairage(CIE)coordinates of(0.14,0.09),and insufficient emission efficiency and stability.The latter problem is due to the highly energetic and hot excited states of these complexes,which yield faster decomposition.Therefore,control of the excited-state properties of cyclometalated Ir(III)complexes through systematic chemical modification of the ligands is being extensively investigated,with the aim of developing efficient and stable blue phosphorescent materials.The most common strategies towards achievement of a blue phosphorescent cyclometalated Ir(III)complex involve(1)substitution of electronwithdrawing F atoms at the cyclometalating ligands that stabilise the HOMO orbitals and(2)use of a heteroleptic system with electron-rich ancillary ligands bearing a 5-membered ring heterocycle to increase the LUMO energy level.However,the C-F bonds on the cyclometalating ligands have been found to be inherently unstable during device operation;thus,other types of electron-withdrawing groups(e.g.,the cyano,trifluoromethyl,and sulfonyl groups)have been applied.Along with phosphorescence colour tuning to blue,the influence of the ligand structure on the photoluminescence quantum yield(PLQY)is also being intensively investigated.Two major PLQY lowering mechanisms for blue emissive Ir(III)complexes have been identified:(1)the vibronic-coupled non-radiative decay process and(2)crossing from the emissive state to an upper non-emissive ^(3)MC excited state.To enhance the PLQY,mechanism(1)can be suppressed by employing rigid ligand frameworks to restrict intramolecular motion,whereas mechanism(2)can be prevented by destabilising the ^(3)MC state using strongσdonor ligands such as N-heterocyclic carbenes.This review summarises the fundamental photophysics of cyclometalated Ir(III)complexes and surveys design strategies for efficient blue phosphorescent Ir(III)complexes,to provide a guide for future research in this field.
文摘In this work,we explore the excited states of three different[Ru(4,4’-BTFMB)_(2)(L)]^(2+)complexes(C1:L=bpy(2,2’-bipyridine);C2:L=phen(1,10-phenantroline);and C3:L=TAP(1,4,5,8-tetraazaphenanthrene)),aiming to investigate the ligand effects on their photophysical and photochemical properties and also to evaluate their suitability as photosensitizers(PS)for photodynamic therapy(PDT).Compound C3 is a new theoretical proposition for which we have observed a significant lowering in the HOMO and LUMO energies,which can be interpreted as an extra stabilization of the complex,a highly desirable feature for a PS candidate.Also,the low-lying excited states showed a shift in the MLCT transition nature from dRu!π*btfmb to dRu!π*tap,confirming that the presence of a more electronegative atom in the third ligand lowers the energy of the orbitals due to a more effectiveπ-backbonding.Furthermore,the investigation of the excited state reactions has shown a dual character possibility for the three complexes,being thermodynamically favorable for photosensitizing molecular oxygen through energy transfer and oxidizing guanosine-monophosphate through electron transfer.Complex C3 presented the best reaction freeenergy profile,indicating that this new compound is most suitable for use as a photosensitizer in PDT.
文摘Hypocrellins are novel photosensitizers from China, which are demonstrated to have significant anti-tumor and anti-virus activity and to be potential photo-dynamic therapy (PDT) agents. As compared with hemato-porphyrin, the only approved photosensitizer, hypocrellins have several advantages, such as easy preparation and easy purification, high triplet quantum yield, high singlet-oxygen quantum yield, high phototoxicity but low dark toxicity, and rapid clearance from normal issues. This article reviews briefly the photophysics, photochemistry and photobiology of hypocrellins on the basis of the domestic and international research results.
基金supported by the National Natural Science Foundation of China(grant nos.22005210,21833005,and 22231009).
文摘Understanding the structure-property relationships in polycyclic conjugated hydrocarbons(PCHs)is crucial in controlling their electronic properties and developing new optically functional materials.Aromaticity is a fundamentally important and intriguing property of numerous organic chemical structures and has stimulated a myriad of experimental and theoretical investigations.Exploiting aromaticity rules for the rational design of optoelectronic materials with the desired photophysical characteristics is a challenging yet fascinating task.Herein we present an in-depth computational and spectroscopic study on the structure-property relationships of dinaphthopentalenes(DNPs).Results highlight that the different fusion patterns between 4nπand 4n+2πunits endow these PCHs with the tunable aromaticity in the ground state/excited state,which leads to the diverse electronic structures and consequently the distinctive excited state photophysics.Accordingly,we propose a combined aromaticity design strategy for rationally modulating and tailoring electronic and optical properties of PCH skeletons.These outcomes not only present a full picture of the excited state dynamics of the DNP system and afford a new class of efficient singlet fission-active materials but also provide some basic guidelines for exploiting aromaticity rules to design and develop new optical function materials.
基金Project suplorted b＇y the National Natural Science Foundation of China （Nos. 50773049, 20974075） and the Program of Innovative Research Team of Soochow University and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘A series of poly（p-phenylenevinylene）s （PPVs） with good solubility were synthesized from thermal elimination of precursor poly（2,5-didodecyloxy-p-phenylenevinylene） at different temperature via Wessling method. The polymer photophysics were influenced by the thermal elimination condition, which was consistent with NMR and IR characterizations. The additional absorption peak at longer wavelength and the red-shifted emission maximum both in solution and in film, for PPVs obtained at high elimination temperature, indicated the existence of longer conjugated blocks in these systems. The emission maximum for drop-cast film （436 nm） for PPV obtained under 200 ℃ （PPV200） was 16 nm blue shifted to the spin-coated films （452 nm） or 29 nm to the solution （465 nm）. The SEM study showed drop-cast film had the morphology of isolated conjugated particles in the matrix while blurry linear structure was found for spin-coated film, which was consistent with the photophysics. The discussion about this difference was carried out based on the consideration of the flexibility of the polymer chains and different conjugated length of PPV in different states.
基金Project supported by the National Natural Science Foundation of China.
文摘The fluorescence spectra of N--salicylidene-p-(N,N--dimethylamino)aniline have beeninvestigated in various solvents. Three kinds of fluorescence have been found in the solutionsof various concentrations. They are the excited intermediate (EI) which is formed when theproton transfer has occurred but essentially retains the geometry of the enol tautomer, theexciplex (EX) which consists of a ground monomer and an excited state intermediate and theexcited dimer (ED) which is caused by ground state aggregate. The fluorescence lifetimesof the fluorophores have been measured in tetrahydrofuran (THF). Luminescent mechanismhas been discussed based on the fluorescence spectra and the kinetic data of the compound.
文摘9-Fluorenylidenemalononitrile (FDCN) or 1,1 diphenyl 2,2 dicyanoethylene (DPCN) reacted with 10 methyl 9,10 dihydroacridine (AcrH 2) under irradiation ( λ >320 nm) to give couping products. In order to gain further insight into the mechanism of the photo induced reaction, the photophysics of the reactions of FDCN or DPCN with AcrH 2 have been investigated by using UV vis spectroscopy, fluorescence spectroscopy, excitation spectroscopy and time resolved fluorescence spectroscopy, respectively. The results show that FDCN or DPCN interacts with AcrH 2 in the ground states to form a charge transfer complex, which further reacts to give the coupling product upon irradiation.
基金The project was supported by the National Natural Science Foundation of Chinathe Applied Organic Laboratory,Lanzhou University.
文摘The quenching processes of the excited singlet state of pyrene by triphenylamine,diphenyl- amine and N,N-dibenzylaniline in various solvents at room and lower temperature have been stu- died with both static state fluorescence spectroscopy and fluorescence lifetime techniques.On the basis of experimental data,a preliminary quenching mechanism has been discussed.The geome- trical configuration models of the exciplexes formed between the excited pyrene and aromatic ami- nes in nonpolar solvents were proposed.
基金supported by the National Natural Science Foundation of China(Nos.92156021,22350009,and 22101115)Financial Support for Outstanding Talents Training Fund in Shenzhen,the Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)+2 种基金high level of special funds(No.G03050K003)Introduction of Major Talent Projects in Guangdong Province(No.2019CX01C079)supported by the Center for Computational Science and Engineering at SUSTech.
文摘Azulene-fused acenes demonstrate enhanced stability,unique aromaticity,and distinctive photophysical properties,rendering them significant in organic electronics.In the present study,we report a new type of nonalternant analogue of pentacene incorporating a non-terminal azulene unit.Aromaticity analyses reveal that the five-membered rings in this analogue exhibit antiaromatic.The extensive conjugated aryl substituents on the acene’s side shift the HOMO distributions from the naphthyl ring and metallacycle to the aryl groups,thereby narrowing the HOMO-LUMO energy gap and enhancing absorptions in the low-energy regions.Furthermore,these fused acenes readily react with base rather than acid,resulting in reversible base/acid stimuli responsiveness.
文摘Green-emitting iridium(Ⅲ)complexes were synthesised using chlorobridged dimer(ppy)_(2)Ir_(2)Cl_(2)(ppy)_(2),3-hydroxy-2-methyl-γ-pyranone,2-ethyl-3-hydroxy-4-pyranone,and 5-hydroxy-2-(hydroxymethyl)-1,4-pyranone as the auxiliary ligand.The structure of the target product was characterised by nuclear magnetic resonance spectroscopy(~1H-NMR),infrared spectroscopy(IR)and mass spectrometry(MS),and its thermal stability,photophysical properties and electrochemical properties were investigated.The results show that the decomposition temperatures of Ir1,Ir2 and Ir3 are 349,292 and 200℃,respectively.The maximum emission wavelength of Ir1,Ir2 and Ir3 dissolved in dichloromethane is 491 nm.The HOMO energy level of Ir1,Ir2 and Ir3 are 5.39,-5.38,and-5.30 eV.The LUMO energy levels are-2.86,-2.85,and-2.80 eV,respectively.
基金the National Natural Science Foundation of China(NSFC,Nos.50673094 and 20774102) for financial support
文摘A series of poly（aryleneethynylene）s containing dibenzosilole unit has been synthesized by palladium-catalyzed Sonogashira cross-coupling reactions with 2,7-diethynyl-9,9-dihexyl-3,6-dimethoxy-9H-dibenzosilole （4） as the key monomer. Their photophysical properties in solution were investigated. All of the polymers showed intense fluorescence with high quantum efficiencies.
基金financially supported by the Shandong Provincial Natural Science Foundation(Nos.ZR2019YQ19 and ZR2019BEM018)the Project of Shandong Province Higher Educational Science and Technology Program(No.2019KJA026)the National Natural Science Foundation of China(Nos.51403113 and 52072193)。
文摘Organic color-tunable phosphorescent materials depend upon multiple emission centers to achieve colortunable phosphorescence with changes in excitation wavelength,temperature,time,and other external factors.Organic color-tunable phosphorescent materials are becoming increasingly popular due to their potential applications in anticounterfeiting,encryption and sensing.This brief review focuses on the formation of multiple emission centers in organic color-tunable phosphorescent materials and how to ensure that these multiple emission centers can simultaneously emit.In the future,materials with a large color tunable ranges,increased efficiency,and relatively long lives will be developed.
基金Supported by the Natural Science Foundation of Henan Province (No. 102100410221)the Natural Science Foundation of Nanyang Normal University (No. ZX2010012)the Young Core Instructor from the Education Commission of Henan Province
文摘A novel Ru（Ⅱ） complex [（bpy）2Ru（PBC）]（PF6）2 （PBC = N-[4-（9-carbazole）butyl]-2-（2-pyridyl）benzimidazole） has been synthesized and verified by 1↑H NMR, elemental analysis and X-ray crystallography. The crystal （C48H40F12N8P2Ru, Mr = 1119.89） belongs to the triclinic system, space group P1, with a = 13.128（4）, b = 13.814（4）, c = 14.184（4） A, α = 84.112（6）, β = 88.473（6）, γ = 78.196（6）°, Z = 2, V = 2504.6（13）A^3, Dc = 1.485 g/cm^3, F（000） = 1132, R = 0.0750 and wR = 0.1896. The Ru atom adopts a distorted-octahedral coordination geometry with the bond distances and bond angles falling in normal ranges. The complex shows an intense metal-to-ligand charge transfer （1MLCT） （dπ（Ru） →π＊（L）） transition （ε ~1.2×10^4 dm^3mol^-1cm^-1） at 457 nm in the UV-Vis absorption spectrum and a strong red phosphorescence at 632 nm in the CH3CN solution at ambient temperature. An efficient intramolecular energy transfer process from the carbazole unit to the [（bpy）2Ru（PB）]^2＋ emissive center exists by selective optical-simulation. Its electrochemical behavior shows multiplicate redox processes based on the metal center, the grafting carbazole moiety and the 2-（2-pyridyl）benzimidazole unit.
基金the National Science Foundation of China(22205197)the project funded by China Postdoctoral Science Foundation(2022M712721)the Youth Talent Excellence Program of ZJU-Hangzhou Global Scientific and Technological Innovation Center.
文摘Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to the unclear relationship between the non-conjugated structure and TSI properties.Herein,the TSI in diphenylmethane is manipulated by breaking its symmetric structures and changing the isolated subunits.Finally,the CL wavelength and efficiency of diphenylmethane are successfully regulated at the aggregate state.
基金financially supported by the Natural Science Foundation of Jiangsu Higher Education Institutions (No. 18KJA430014)the Natural Science Foundation of Jiangsu Province (No. BK20181441)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on the DPP moiety. The polymers were found to have designed chemical structures via structural characterizations in comparison with three monomers. The molecular weight measurement further demonstrated the formation of polymers with polydispersity index around 2, consistent with the polycondensation nature of the polymerization based on Sonogashira coupling. Both polymers could dissolve in many organic solvents, and the one with long alkyl side group on DPP moiety had better solubility. Photophysical investigation showed that both polymers had typical absorption/emission of conjugated polymers, and varying the solvent did not have large influence. Compared with other polar solvents, toluene reduced the quantum yield of fluorescence of the polymers, especially for the one with long alkyl pedant group, accompanying with slight red-shift in absorption/emission. The difference in the absorption/emission wavelengths between the polymers was similar to that between the corresponding monomers. Adding water into the THF solution of polymers reduced the emission intensity but no redshift was observed. Discussion about the structure-property relationships was carried out in detail.
基金supported by the Open Fund of the State Key Laboratory of Molecular Reaction Dynamics at Dalian Institute of Chemical Physics,Chinese Academy of Sciences(No.SKLMRD-K202108)。
文摘Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar cells.Copper phthalocyanine(CuPc)is a typical electron acceptor.In this work,the triplet exciton lifetime is prolonged by altering the molecular stacking pattern of the CuPc film.For CuPc thin films,the excited state decays are mainly determined by the triplet-triplet annihilation process.The ultrafast transient absorption measurements indicate that the primary annihilation mechanism is one-dimensional exciton diffusion collision destruction.The decay kinetics show a clearly time-dependent annihilation rate constant withγ∝t^(-1/2).Annihilation rate constants are determined to beγ0=(2.87±0.02)×10^(-20)cm^(3)·s^(-1/2)and(1.42±0.02)×10^(-20)cm^(3)·s^(-1/2)for upright and lyingdown configurations,respectively.Compared to the CuPc thin film with an upright configuration,the thin film with a lying-down configuration shows longer exciton lifetime and higher absorbance,which are beneficial to organic solar cells.The results in this work have important implications on the design and mechanistic understanding of organic optoelectronic devices.
