Singlet fission(SF)is a spin-conserving process converting 1 singlet exciton into 2 triplet excitons.This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction ...Singlet fission(SF)is a spin-conserving process converting 1 singlet exciton into 2 triplet excitons.This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley–Queisser limit.However,it remains unclear how intermolecular coupling,which is subject to the aggregation extent in thin-film morphology,controls SF pathways and dynamics.The prototype molecule 6,13-bis(triisopropylsilylethynyl)-pentacene(TIPS-pentacene)has been extensively studied to investigate SF mechanisms.However,previous literature reports have presented divergent SF mechanisms and pathways in TIPS-pentacene films.In this study,solvent vapor annealing treatment is used to deliberately adjust the aggregation extent in TIPS-pentacene films.This enables us to reproduce various SF pathways reported in the literature under the same experimental conditions,with the only variation being the level of aggregation.These results shed light on the crucial role that molecular aggregation plays in modulating both the SF mechanism and pathway and reconciles the previously contentious SF mechanisms and pathways reported in TIPS-pentacene films.Our study offers substantial insights into the understanding of the SF mechanism and provides a potential avenue for future control of SF pathways in accordance with specific application requirements.展开更多
The instability of perovskite materials under continuous ultraviolet(UV)light irradiation and high sensitivity in humid environments remain obstacles to future commercialization.Especially,the photovoltaic performance...The instability of perovskite materials under continuous ultraviolet(UV)light irradiation and high sensitivity in humid environments remain obstacles to future commercialization.Especially,the photovoltaic performance of perovskite solar cells(PVSCs)is prone to decline under UV light exposure for sustained periods of time.However,in conventional methods,preventing UV light from entering PVSCs usually comes at the expense of reducing short circuit photocurrent(Jsc).Herein,the UV stability of PVSCs is modified by in-troducing a singlet fission down-conversion layer 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-PEN)via one-step anti-solvent method without sacrificing device efficiency.The introduction of down conversion layer can not only improve the Jsc by converting UV light into multiple excitons,but also enhance the open-circuit voltage(Voc)owing to a better matched energy level alignment at the perovskite/spiro-OMeTAD interface.Consequently,the TIPS-PEN incorporated PVSCs attain the champion power conversion effi-ciency(PCE)up to 22.92%accompanied with dramatically increased UV photostability which can retain 80%of its primitive PCE un-der continuous UV light soaking for 150 h.Moreover,the unencapsulated PVSCs with TIPS-PEN exhibit remarkable moisture stability which can sustain over 80%of the initial value under air conditions(50%relative humidity,25℃)after 1000 h.展开更多
Singlet fission(SF)has potential applications in high-efficiency photo-energy harvesting applications,but its practical application is hindered by the limited number of materials.In this work,we explored the bay aroma...Singlet fission(SF)has potential applications in high-efficiency photo-energy harvesting applications,but its practical application is hindered by the limited number of materials.In this work,we explored the bay aromatic substitution strategy for the design of new perylenediimide(PDI)based SF materials.A series of PDI derivatives with biphenyl or naphthalene units substituted at the bay posi-tions were designed and synthesized to investigate the effects of aromatic substitutes on their photodynamic behaviours.The bay substitutions do not shift the energy level of the PDI core significantly but give rise to different intermolecular coupling strengths in the thin films and affect the intermolecular SF efficiency.Femtosecond transient absorption(fsTA)spectroscopy reveals that appro-priate spacing configuration from the bay aromatic substitution groups enhances the SF yields by promoting the interaction of neighbouring PDI cores.Triplet exciton yields of up to 183%have been obtained from these new PDI derivatives,making them po-tential candidates in future SF-based optoelectronics.展开更多
The practical efficiency of singlet fission(SF)-based photovoltaic devices is still far from satisfactory due to the limited scope of SF materials suitable for device application and the scarcity of schemes available ...The practical efficiency of singlet fission(SF)-based photovoltaic devices is still far from satisfactory due to the limited scope of SF materials suitable for device application and the scarcity of schemes available for triplet utilization.Most SF materials identi-fied to date are typically electron donors while acceptor-type SF materials remain largely unexplored.Basically,the combination of a conventional electron donor and SF-active electron acceptor could circumvent the competitive energy transfer channel and better play the unique advantages of the SF process,which might be an adequate alternative for practical application.In this work,we presented a new acceptor-type SF material based on a tetracyanothienoquinoid skeleton.Such a quinoid skeleton exhibited strong absorption,ultrafast SF process,and excellent stability.Using transient spectroscopy and multireference calculations(XDWCASPT2),the SF dynamics were examined featuring the rapid generation and subsequent annihilation and/or partial dissociation of multiexciton states.Therefore,our results not only provide a robust acceptor-type SF material but also suggest an adequate donor–acceptor alternative for SF-based solar cells,which could pave the way for the practical application of such a potential process.展开更多
Singlet fission(SF)has attracted much attention on account of its great potential for applications in high efficiency solar energy conversion.The major roadblock to realize this potential is rooted in the limited avai...Singlet fission(SF)has attracted much attention on account of its great potential for applications in high efficiency solar energy conversion.The major roadblock to realize this potential is rooted in the limited availability of practical SF material with strong absorption,suitable triplet energy level,an efficient SF process,and good chemical stability.Quinoidal structures feature an innate diradical character,which endows these skeletons with SF potential yet results in some structural instability.展开更多
The synthesis and characterization of platinum(II)and palladium(II)complexes bearing two(dimers Pt(L_(pc))_(2)Cl_(2)and Pd(L_(pc))_(2)Cl_(2)),one(monomers Pt(L_(pc))(L_(ref))Cl_(2)and Pd(L_(pc))(L_(ref))-Cl_(2)),or no...The synthesis and characterization of platinum(II)and palladium(II)complexes bearing two(dimers Pt(L_(pc))_(2)Cl_(2)and Pd(L_(pc))_(2)Cl_(2)),one(monomers Pt(L_(pc))(L_(ref))Cl_(2)and Pd(L_(pc))(L_(ref))-Cl_(2)),or no(reference compounds Pt(L_(ref))_(2)Cl_(2)and Pd(L_(ref))_(2)Cl_(2))pentacene-based pyridyl ligands are presented.Photophysical properties of the dimers are probed by means of steady-state and time-resolved transient absorption measurements in compar-ison to the monomer and model compounds.Our results document that despite enhanced spin−orbit coupling from the presence of heavy atoms,intramolecular singlet fission(iSF)is not challenged by intersystem crossing.iSF thus yields correlated triplet pairs and even uncorrelated triplet excited states upon decoherence.Importantly,significant separation of the two pentacenyl groups facilitates decoupling of the two chromophores.Furthermore,the mechanism of iSF is altered depending on the respective metal center,that is,Pt(II)versus Pd(II).The dimer based on Pt(II),Pt(L_(pc))2Cl_(2),exhibits a direct pathway for the iSF and forms a correlated triplet pair with singlet−quintet spin-mixing within 10 ns in variable solvents.On the other hand,the dimer based on Pd(II),Pd(L_(pc))_(2)Cl_(2),leads to charge transfer mixing during the population of the correlated triplet pair that is dependent on solvent polarity.Moreover,Pd(L_(pc))_(2)Cl_(2)gives rise to a stable equilibrium between singlet and quintet correlated triplet pairs with lifetimes of up to 170 ns.Inherent differences in the size and polarizability,when contrasting platinum(II)with palladium(II),are the most likely rationale for the underlying trends.展开更多
Singlet fission(SF)is an appealing process where one photoexcited singlet transforms to two triplets,which can overcome thermalization energy loss and improve solar cell efficiency.However,it remains unclear how inter...Singlet fission(SF)is an appealing process where one photoexcited singlet transforms to two triplets,which can overcome thermalization energy loss and improve solar cell efficiency.However,it remains unclear how intermolecular coupling,which is subject to molecular stacking,controls SF pathways and dynamics.Here,we prepared polymorph rubrene single crystals with different stacking geometries,including orthorhombic(Orth.),triclinic(Tri.),and monoclinic(Mono.)phases.By micro-area ultrafast spectroscopy,we find that Orth.and Tri.phases with closerπ-πstacking exhibit co-existing coherent and incoherent SF channels while loosely stacked Mono.phase shows only incoherent SF.Furthermore,incoherent SF is thermally activated in Orth.but barrierless in Mono.and Tri.phases.Quantum mechanical calculation reveals that different electronic coupling strength in different phases leads to different SF dynamics.This study demonstrates that molecular stacking governs SF dynamics through electronic coupling,providing guidance for designing efficient SF materials via crystal structural engineering.展开更多
In intramolecular SF(iSF), the strong coupling nature and confinement of diffusional separation of ^1(TT) limits the extraction and harnessing of triplet energy. In order to investigate the possible ^1(TT) separation ...In intramolecular SF(iSF), the strong coupling nature and confinement of diffusional separation of ^1(TT) limits the extraction and harnessing of triplet energy. In order to investigate the possible ^1(TT) separation and the role of molecular parameters on it, a series of iSF-capable dibenzopentalene derivatives(DBPs) have been synthesized and their photoinduced dynamics are monitored. iSF takes place in DBPs, accompanied by consecutive ^1(TT) separation in polycrystalline film with almost ^100% yield. It is suggested the strong intermolecular coupling provided by the closely packing configuration in the film facilitates the disentanglement of correlated ^1(TT). Highly efficient triplet pair separation to yield free triplets makes one step forward for utilizing triplet energy from iSF materials for further optoelectronic applications.展开更多
Singlet fission has attracted extensive attention from experimentalists and theoreticians due to its ability to improve the photovoltaic conversion efficiency.Still,designing singlet fission materials remains challeng...Singlet fission has attracted extensive attention from experimentalists and theoreticians due to its ability to improve the photovoltaic conversion efficiency.Still,designing singlet fission materials remains challenging.In this work,we explored the relationship between adaptive aromaticity and singlet fission potentials by computationally screening the adaptive aromatic species reported by our group.Adaptive aromaticity refers to species with aromaticity in the lowest singlet and the lowest triplet states,and density functional theory calculations reveal that species with adaptive aromaticity usually generate an intermediate E(T_(1))a value(singlet-triplet gaps).In most cases,species with adaptive aromaticity satisfy the thermodynamic requirements of the singlet fission process(2E(T_(1))<E(S_(1))and 2E(T_(1))<E(T_(2))).Thus,our findings demonstrate that adaptive aromaticity could provide an alternative strategy for experimentalists and theoreticians to design singlet fission materials.展开更多
Organic semiconductor lasers are attractive for low thresholds and cost,but triplet accumulation hampers their electrically pumped development.Compared to existing organic lasing materials,triplet-triplet annihilation...Organic semiconductor lasers are attractive for low thresholds and cost,but triplet accumulation hampers their electrically pumped development.Compared to existing organic lasing materials,triplet-triplet annihilation(TTA)systems are capable of tolerating high triplet concentrations and may facilitate stable laser emission under electrical pumping.To avoid energy losses in doped multicomponent TTA systems,herein,we report an organic semiconductor lasing material BH001 with TTA properties,which combines concurrent triplet harvesting and lasing within a single molecular framework.Dislocations betweenπ-conjugated planes reduceπ-πstacking-induced fluorescence quenching,yielding high photoluminescence quantum yield(PLQY)in the crystal.The TTA process in BH001 can be observed through a color change from red to blue by the sensitization of PtOEP.Given that nanosecond/femtosecond transient absorption(ns-TA and fs-TA)spectroscopy has demonstrated the appreciable ability of BH001 to generate triplet states,TTA-delayed fluorescence of pure BH001 crystal was directly detected using a streak camera.A laser constructed from this TTA crystal achieved low-threshold blue emission at 440 nm(P_(th)=15.4μJ/cm^(2)),which is increased in an oxygen atmosphere,suggesting the involvement of triplets.Upon excitation with nanosecond laser pulses that are more prone to cause triplet stacking,the BH001 crystal exhibits stimulated emission behavior.This study demonstrates a lasing molecule with TTA properties,highlighting its potential in continuous wave(CW)pumped and ultimately electrically pumped systems.展开更多
Afterglow materials have drawn considerable attention for a long time due to their unique luminescence properties,among which lanthanide-doped persistent phosphors have been extensively investigated and even commercia...Afterglow materials have drawn considerable attention for a long time due to their unique luminescence properties,among which lanthanide-doped persistent phosphors have been extensively investigated and even commercialized.However,afterglow luminescence from lanthanides has been sporadically achieved in non-crystalline materials.Herein,ultrabright red afterglow in organic solution is observed to share an identical emission profile of an f-f transition Eu-complex.In this well-designed afterglow system,a sensitizer with singlet fission ability and zero-overlapped wavefunction between the lanthanide emitter was introduced,to implement effective photochemical reactions and energy transfer processes.The photochemical afterglow solution is applicable to wet-chemical procedure for the ondemand fabrication of functional nanoparticles with uniform size.Homogeneous immunoassay conformed to photochemical afterglow regime was performed with a detection limit of 0.5 pg/mL for interleukin-6.These results not only advance photochemical afterglow for optimal performance,but also pave the way for rational design of lanthanide luminescence materials with ultralong lifetime.展开更多
Singlet fission(SF)holds great promise for advancing optoelectron-ics,with ultrafast timescales and high exciton yield per absorbed photon.Despite extensive experimental and theoretical investigations,under-standing t...Singlet fission(SF)holds great promise for advancing optoelectron-ics,with ultrafast timescales and high exciton yield per absorbed photon.Despite extensive experimental and theoretical investigations,under-standing the nature of charge-trans-fer and triplet-pair states remains challenging.Our previous study on cyclopentadithiophene-based quinoidal-biradical resonance structures[Phys.Chem.Chem.Phys.25,29698(2023)]revealed their excellent tunability in chemical structure for SF.While the ultrafast dynamics in the excited state have not been fully explored,experimental data in-dicate a singlet excited state lifetime of approximately 2.1 ps.In our current study,we em-ploy excited-state dynamics simulations to theoretically investigate the formation of charge-transfer(CT)configuration during the SF process.Our simulations reveal correlated rotation-al angles of fluorenes,ranging from−40°to 60°,and detect primary charge transfer from the two fluorene moieties to the dithiophene fragment.Interestingly,the direction of charge transfer may alter within the simulation timeframe of hundreds of femtoseconds.Our theoret-ical simulations provide an informative reference for future design in SF.展开更多
Organic optoelectronics have received tremendous attentions in the past few decades,which are benefitting from the rapid development of organic semiconductors and their unique merits such as flexible design,low-cost p...Organic optoelectronics have received tremendous attentions in the past few decades,which are benefitting from the rapid development of organic semiconductors and their unique merits such as flexible design,low-cost production,and rich optoelectronic properties.Triplet excitons with two parallel electronic spins generated in the organic optoelectronic devices have significant effects on the device performance.In this review,a timely summary and brief discussion of the management and utilization of the triplet excitons in organic optoelectronic devices are given.We firstly summarized the studies and applications of triplet excitons in optical-to-electrical and electrical-to-optical devices,including solar cells,organic light-emitting diodes(OLEDs)and organic light-emitting transistors(OLETs).Particularly,the pioneering advances of triplet management in OLETs are reviewed for the first time.Additionally,two possible strategies for breaking the theoretical limit of internal quantum efficiency(IQE)in electroluminescent devices by fully taking the advantages of triplet excitons are proposed.Finally,the challenges and perspective of existing issues in this field for further improving the performance of optoelectronic devices and other related research directions are also provided.展开更多
基金supported by the National Natural Science Foundation of China(62375056 and 11874125)the Guangdong Basic and Applied Basic Research Foundation(2022A1515011951).
文摘Singlet fission(SF)is a spin-conserving process converting 1 singlet exciton into 2 triplet excitons.This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley–Queisser limit.However,it remains unclear how intermolecular coupling,which is subject to the aggregation extent in thin-film morphology,controls SF pathways and dynamics.The prototype molecule 6,13-bis(triisopropylsilylethynyl)-pentacene(TIPS-pentacene)has been extensively studied to investigate SF mechanisms.However,previous literature reports have presented divergent SF mechanisms and pathways in TIPS-pentacene films.In this study,solvent vapor annealing treatment is used to deliberately adjust the aggregation extent in TIPS-pentacene films.This enables us to reproduce various SF pathways reported in the literature under the same experimental conditions,with the only variation being the level of aggregation.These results shed light on the crucial role that molecular aggregation plays in modulating both the SF mechanism and pathway and reconciles the previously contentious SF mechanisms and pathways reported in TIPS-pentacene films.Our study offers substantial insights into the understanding of the SF mechanism and provides a potential avenue for future control of SF pathways in accordance with specific application requirements.
基金financially supported by the National Natural Science Foundation of China(NSFC)(52063019,51973088,51963016,51833004,U20A20128,U1801256)"Key Project of Jiangxi Provincial Natural Science Foundation(20224ACB203007)".
文摘The instability of perovskite materials under continuous ultraviolet(UV)light irradiation and high sensitivity in humid environments remain obstacles to future commercialization.Especially,the photovoltaic performance of perovskite solar cells(PVSCs)is prone to decline under UV light exposure for sustained periods of time.However,in conventional methods,preventing UV light from entering PVSCs usually comes at the expense of reducing short circuit photocurrent(Jsc).Herein,the UV stability of PVSCs is modified by in-troducing a singlet fission down-conversion layer 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-PEN)via one-step anti-solvent method without sacrificing device efficiency.The introduction of down conversion layer can not only improve the Jsc by converting UV light into multiple excitons,but also enhance the open-circuit voltage(Voc)owing to a better matched energy level alignment at the perovskite/spiro-OMeTAD interface.Consequently,the TIPS-PEN incorporated PVSCs attain the champion power conversion effi-ciency(PCE)up to 22.92%accompanied with dramatically increased UV photostability which can retain 80%of its primitive PCE un-der continuous UV light soaking for 150 h.Moreover,the unencapsulated PVSCs with TIPS-PEN exhibit remarkable moisture stability which can sustain over 80%of the initial value under air conditions(50%relative humidity,25℃)after 1000 h.
基金supported by the National Natural Science Foundation of China(NSFC 51733004,51525303,21702085,21602093,21572086,22075117,92256202,U22A20399)the Fundamental Research Funds for the Central Universities(lzujbky-2022-kb01,Izujbky-2021-sp33,Izujbky-2021-27),and Supercomputing Center of Lanzhou University.
文摘Singlet fission(SF)has potential applications in high-efficiency photo-energy harvesting applications,but its practical application is hindered by the limited number of materials.In this work,we explored the bay aromatic substitution strategy for the design of new perylenediimide(PDI)based SF materials.A series of PDI derivatives with biphenyl or naphthalene units substituted at the bay posi-tions were designed and synthesized to investigate the effects of aromatic substitutes on their photodynamic behaviours.The bay substitutions do not shift the energy level of the PDI core significantly but give rise to different intermolecular coupling strengths in the thin films and affect the intermolecular SF efficiency.Femtosecond transient absorption(fsTA)spectroscopy reveals that appro-priate spacing configuration from the bay aromatic substitution groups enhances the SF yields by promoting the interaction of neighbouring PDI cores.Triplet exciton yields of up to 183%have been obtained from these new PDI derivatives,making them po-tential candidates in future SF-based optoelectronics.
基金supported by the National Natural Science Foundation of China(NSFC,grant no.22005210)by the Fundamental Research Program of Shanxi Province,China(grant nos.202203021224004 and 20210302124469).
文摘The practical efficiency of singlet fission(SF)-based photovoltaic devices is still far from satisfactory due to the limited scope of SF materials suitable for device application and the scarcity of schemes available for triplet utilization.Most SF materials identi-fied to date are typically electron donors while acceptor-type SF materials remain largely unexplored.Basically,the combination of a conventional electron donor and SF-active electron acceptor could circumvent the competitive energy transfer channel and better play the unique advantages of the SF process,which might be an adequate alternative for practical application.In this work,we presented a new acceptor-type SF material based on a tetracyanothienoquinoid skeleton.Such a quinoid skeleton exhibited strong absorption,ultrafast SF process,and excellent stability.Using transient spectroscopy and multireference calculations(XDWCASPT2),the SF dynamics were examined featuring the rapid generation and subsequent annihilation and/or partial dissociation of multiexciton states.Therefore,our results not only provide a robust acceptor-type SF material but also suggest an adequate donor–acceptor alternative for SF-based solar cells,which could pave the way for the practical application of such a potential process.
基金supported by the National Natural Science Foundation of China(nos.22005210,21833005,and 21833006).
文摘Singlet fission(SF)has attracted much attention on account of its great potential for applications in high efficiency solar energy conversion.The major roadblock to realize this potential is rooted in the limited availability of practical SF material with strong absorption,suitable triplet energy level,an efficient SF process,and good chemical stability.Quinoidal structures feature an innate diradical character,which endows these skeletons with SF potential yet results in some structural instability.
文摘The synthesis and characterization of platinum(II)and palladium(II)complexes bearing two(dimers Pt(L_(pc))_(2)Cl_(2)and Pd(L_(pc))_(2)Cl_(2)),one(monomers Pt(L_(pc))(L_(ref))Cl_(2)and Pd(L_(pc))(L_(ref))-Cl_(2)),or no(reference compounds Pt(L_(ref))_(2)Cl_(2)and Pd(L_(ref))_(2)Cl_(2))pentacene-based pyridyl ligands are presented.Photophysical properties of the dimers are probed by means of steady-state and time-resolved transient absorption measurements in compar-ison to the monomer and model compounds.Our results document that despite enhanced spin−orbit coupling from the presence of heavy atoms,intramolecular singlet fission(iSF)is not challenged by intersystem crossing.iSF thus yields correlated triplet pairs and even uncorrelated triplet excited states upon decoherence.Importantly,significant separation of the two pentacenyl groups facilitates decoupling of the two chromophores.Furthermore,the mechanism of iSF is altered depending on the respective metal center,that is,Pt(II)versus Pd(II).The dimer based on Pt(II),Pt(L_(pc))2Cl_(2),exhibits a direct pathway for the iSF and forms a correlated triplet pair with singlet−quintet spin-mixing within 10 ns in variable solvents.On the other hand,the dimer based on Pd(II),Pd(L_(pc))_(2)Cl_(2),leads to charge transfer mixing during the population of the correlated triplet pair that is dependent on solvent polarity.Moreover,Pd(L_(pc))_(2)Cl_(2)gives rise to a stable equilibrium between singlet and quintet correlated triplet pairs with lifetimes of up to 170 ns.Inherent differences in the size and polarizability,when contrasting platinum(II)with palladium(II),are the most likely rationale for the underlying trends.
基金National Natural Science Foundation of China,Grant/Award Numbers:22273084,22073045。
文摘Singlet fission(SF)is an appealing process where one photoexcited singlet transforms to two triplets,which can overcome thermalization energy loss and improve solar cell efficiency.However,it remains unclear how intermolecular coupling,which is subject to molecular stacking,controls SF pathways and dynamics.Here,we prepared polymorph rubrene single crystals with different stacking geometries,including orthorhombic(Orth.),triclinic(Tri.),and monoclinic(Mono.)phases.By micro-area ultrafast spectroscopy,we find that Orth.and Tri.phases with closerπ-πstacking exhibit co-existing coherent and incoherent SF channels while loosely stacked Mono.phase shows only incoherent SF.Furthermore,incoherent SF is thermally activated in Orth.but barrierless in Mono.and Tri.phases.Quantum mechanical calculation reveals that different electronic coupling strength in different phases leads to different SF dynamics.This study demonstrates that molecular stacking governs SF dynamics through electronic coupling,providing guidance for designing efficient SF materials via crystal structural engineering.
基金supported by the National Natural Science Foundation of China (21573251, 21833005)the National Basic Research Program of China (2017YFA0204503)+1 种基金the Beijing Natural Science Foundation of China (2162011)Project of State Key Laboratory on Integrated Optoelectronics of Jilin University (IOSKL2014KF16)
文摘In intramolecular SF(iSF), the strong coupling nature and confinement of diffusional separation of ^1(TT) limits the extraction and harnessing of triplet energy. In order to investigate the possible ^1(TT) separation and the role of molecular parameters on it, a series of iSF-capable dibenzopentalene derivatives(DBPs) have been synthesized and their photoinduced dynamics are monitored. iSF takes place in DBPs, accompanied by consecutive ^1(TT) separation in polycrystalline film with almost ^100% yield. It is suggested the strong intermolecular coupling provided by the closely packing configuration in the film facilitates the disentanglement of correlated ^1(TT). Highly efficient triplet pair separation to yield free triplets makes one step forward for utilizing triplet energy from iSF materials for further optoelectronic applications.
基金project was supported by the National Natural Science Foundation of China(21172184)the Top-Notch Young Talents Program of China is gratefully acknowledged.
文摘Singlet fission has attracted extensive attention from experimentalists and theoreticians due to its ability to improve the photovoltaic conversion efficiency.Still,designing singlet fission materials remains challenging.In this work,we explored the relationship between adaptive aromaticity and singlet fission potentials by computationally screening the adaptive aromatic species reported by our group.Adaptive aromaticity refers to species with aromaticity in the lowest singlet and the lowest triplet states,and density functional theory calculations reveal that species with adaptive aromaticity usually generate an intermediate E(T_(1))a value(singlet-triplet gaps).In most cases,species with adaptive aromaticity satisfy the thermodynamic requirements of the singlet fission process(2E(T_(1))<E(S_(1))and 2E(T_(1))<E(T_(2))).Thus,our findings demonstrate that adaptive aromaticity could provide an alternative strategy for experimentalists and theoreticians to design singlet fission materials.
基金the NSFC(22303056,22173062,22150005,22433005,22090022,and 22275125)the National Key Research and Development Program of China(2022YFA1204402,2018YFA0704805,and 2018YFA0704802)+3 种基金the Natural Science Foundation of Beijing,China(KZ202110028043)R&D Program of Beijing Municipal Education Commission(KM202410028016,BPHR202203119)the Science and Technology Innovation Program of Hunan Province(2022RC4039)State Key Laboratory of Fine Chemicals,Dalian University of Technology(KF2313)for financial support.
文摘Organic semiconductor lasers are attractive for low thresholds and cost,but triplet accumulation hampers their electrically pumped development.Compared to existing organic lasing materials,triplet-triplet annihilation(TTA)systems are capable of tolerating high triplet concentrations and may facilitate stable laser emission under electrical pumping.To avoid energy losses in doped multicomponent TTA systems,herein,we report an organic semiconductor lasing material BH001 with TTA properties,which combines concurrent triplet harvesting and lasing within a single molecular framework.Dislocations betweenπ-conjugated planes reduceπ-πstacking-induced fluorescence quenching,yielding high photoluminescence quantum yield(PLQY)in the crystal.The TTA process in BH001 can be observed through a color change from red to blue by the sensitization of PtOEP.Given that nanosecond/femtosecond transient absorption(ns-TA and fs-TA)spectroscopy has demonstrated the appreciable ability of BH001 to generate triplet states,TTA-delayed fluorescence of pure BH001 crystal was directly detected using a streak camera.A laser constructed from this TTA crystal achieved low-threshold blue emission at 440 nm(P_(th)=15.4μJ/cm^(2)),which is increased in an oxygen atmosphere,suggesting the involvement of triplets.Upon excitation with nanosecond laser pulses that are more prone to cause triplet stacking,the BH001 crystal exhibits stimulated emission behavior.This study demonstrates a lasing molecule with TTA properties,highlighting its potential in continuous wave(CW)pumped and ultimately electrically pumped systems.
基金Project supported by the National Key R&D Program of China(2023YFC3605700)。
文摘Afterglow materials have drawn considerable attention for a long time due to their unique luminescence properties,among which lanthanide-doped persistent phosphors have been extensively investigated and even commercialized.However,afterglow luminescence from lanthanides has been sporadically achieved in non-crystalline materials.Herein,ultrabright red afterglow in organic solution is observed to share an identical emission profile of an f-f transition Eu-complex.In this well-designed afterglow system,a sensitizer with singlet fission ability and zero-overlapped wavefunction between the lanthanide emitter was introduced,to implement effective photochemical reactions and energy transfer processes.The photochemical afterglow solution is applicable to wet-chemical procedure for the ondemand fabrication of functional nanoparticles with uniform size.Homogeneous immunoassay conformed to photochemical afterglow regime was performed with a detection limit of 0.5 pg/mL for interleukin-6.These results not only advance photochemical afterglow for optimal performance,but also pave the way for rational design of lanthanide luminescence materials with ultralong lifetime.
基金supported by the National Natural Science Foundation of China(No.22173017)the Shanghai Municipal Science and Technology Commission(No.22511103900)the Fundamental Research Funds for the Central Universities(No.2232023A-02)。
文摘Singlet fission(SF)holds great promise for advancing optoelectron-ics,with ultrafast timescales and high exciton yield per absorbed photon.Despite extensive experimental and theoretical investigations,under-standing the nature of charge-trans-fer and triplet-pair states remains challenging.Our previous study on cyclopentadithiophene-based quinoidal-biradical resonance structures[Phys.Chem.Chem.Phys.25,29698(2023)]revealed their excellent tunability in chemical structure for SF.While the ultrafast dynamics in the excited state have not been fully explored,experimental data in-dicate a singlet excited state lifetime of approximately 2.1 ps.In our current study,we em-ploy excited-state dynamics simulations to theoretically investigate the formation of charge-transfer(CT)configuration during the SF process.Our simulations reveal correlated rotation-al angles of fluorenes,ranging from−40°to 60°,and detect primary charge transfer from the two fluorene moieties to the dithiophene fragment.Interestingly,the direction of charge transfer may alter within the simulation timeframe of hundreds of femtoseconds.Our theoret-ical simulations provide an informative reference for future design in SF.
基金support from the Ministry of Science and Technology of China(2022YFB3603800,2023YFB3609000)the Natural Science Foundation of China(52233010,52103245,and 22021002)+3 种基金the CAS Project for Young Scientists in Basic Research(YSBR-053)the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202012)the Australian Research Council(ARC DP200103036)support from the Australian Research Council through the ARC centre of Excellence in Exciton Science(CE170100026).
文摘Organic optoelectronics have received tremendous attentions in the past few decades,which are benefitting from the rapid development of organic semiconductors and their unique merits such as flexible design,low-cost production,and rich optoelectronic properties.Triplet excitons with two parallel electronic spins generated in the organic optoelectronic devices have significant effects on the device performance.In this review,a timely summary and brief discussion of the management and utilization of the triplet excitons in organic optoelectronic devices are given.We firstly summarized the studies and applications of triplet excitons in optical-to-electrical and electrical-to-optical devices,including solar cells,organic light-emitting diodes(OLEDs)and organic light-emitting transistors(OLETs).Particularly,the pioneering advances of triplet management in OLETs are reviewed for the first time.Additionally,two possible strategies for breaking the theoretical limit of internal quantum efficiency(IQE)in electroluminescent devices by fully taking the advantages of triplet excitons are proposed.Finally,the challenges and perspective of existing issues in this field for further improving the performance of optoelectronic devices and other related research directions are also provided.
