为了研究红荧烯（5,6,11,12-tetraphenylnaphthacene,Rubrene）器件中三重态激子与电荷相互作用的微观过程,制备了基于Rubrene的有机发光二极管,并测量了室温下器件的磁电导（magneto-conductance,MC）.实验发现,器件MC曲线的幅值非常...为了研究红荧烯（5,6,11,12-tetraphenylnaphthacene,Rubrene）器件中三重态激子与电荷相互作用的微观过程,制备了基于Rubrene的有机发光二极管,并测量了室温下器件的磁电导（magneto-conductance,MC）.实验发现,器件MC曲线的幅值非常小且表现出了奇特的变化：即在0-8 m T的磁场范围内,MC随磁场快速增大;当磁场处于8-100 m T时,MC则表现为下降;但当磁场大于100 m T时,MC则表现为缓慢增加.分析发现,Rubrene器件中除了超精细相互作用外,还有空穴对三重态激子的解离作用和三重态激子对电子的散射作用的共存,且它们都受单重态激子分裂（singlet fission）的影响.利用Lorentzian和non-Lorentzian经验函数可以对MC进行较好拟合,进一步证实了上述观点.三重态激子解离和电子散射共存这一发现不仅有助于对Rubrene器件中电荷与激发态间相互作用机制的认识,在优化器件性能方面也有一定的指导意义.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)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
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)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
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
The cooperative interaction distance measure has been proposed as a novel law pertaining to dialectics of nature, and has been extensively carried out in the design of functional nanomaterials. However, the temporal a...The cooperative interaction distance measure has been proposed as a novel law pertaining to dialectics of nature, and has been extensively carried out in the design of functional nanomaterials. However, the temporal and spatial dimensions are akin to yin and yang, and thus temporal regulation needs to be accounted for when implementing the above-mentioned principle. Here, we summarize recent advances in temporally and spatially regulated materials and devices. We showcase the temporal regulation of organic semiconductors for organic photovoltaics （OPVs） using the example of exciton lifetime manipulation. As an example of spatial regulation, we consider the distribution of charge carriers in core-shell quantum dot （QD） nanocrystals for modulating their optical properties. Long exciton lifetime can in principle increase the exciton diffussion length, which is desiable for high-efficiency large-area OPV devices. Spatially regulated QDs are highly valuable emitters for light-emitting applications. We aim to show that cooperative spatio-temporal regulation of nanomaterils is of vital importance to the development of functional devices.展开更多
The β-carotene（β-Car） aggregate was prepared by self-assembly in cetyltrimethylammoniuln bromide （CTAB） micelle. The ground state absorption measurement showed that the aggregate has J-type characteristics and r...The β-carotene（β-Car） aggregate was prepared by self-assembly in cetyltrimethylammoniuln bromide （CTAB） micelle. The ground state absorption measurement showed that the aggregate has J-type characteristics and resonance Raman spectra gave the intrinsic explanation of molecular interaction in aggregate. Upon excitation at the optical allowed S2 state of aggregate, direct generation of triplet state via singlet fission（SF）mechanism was observed. Excitation dynamics was elucidated by fs-transient absorption spectroscopy and ns-flash photolysis, respectively. The triplet state life time of aggregate was found to be independent of the ambient oxygen molecules.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 structure and excited state properties of the H- and J-aggregates of the marine carbonyl carotenoid, fucoxanthin(Fx), were studied by various spectroscopic methods, and compared with those of Fx monomers in polar ...The structure and excited state properties of the H- and J-aggregates of the marine carbonyl carotenoid, fucoxanthin(Fx), were studied by various spectroscopic methods, and compared with those of Fx monomers in polar organic solvents. The fluorescent analysis indicated tliat the higher vibronic states of S2 contribute more to populating the S1 state, from which fluorescent emission mainly originates. Resonance Raman and density functional theory calculations confirmed the ‘card-packed' and chead-to-taiF structures of the H- and J-aggregates of Fx, respectively. An fs time-resolved absorption study proved the coexistence of Si and intramolecular charge transfer relaxation pathways upon excitation to the S2 state for both tlie monomers and aggregates.展开更多
文摘为了研究红荧烯（5,6,11,12-tetraphenylnaphthacene,Rubrene）器件中三重态激子与电荷相互作用的微观过程,制备了基于Rubrene的有机发光二极管,并测量了室温下器件的磁电导（magneto-conductance,MC）.实验发现,器件MC曲线的幅值非常小且表现出了奇特的变化：即在0-8 m T的磁场范围内,MC随磁场快速增大;当磁场处于8-100 m T时,MC则表现为下降;但当磁场大于100 m T时,MC则表现为缓慢增加.分析发现,Rubrene器件中除了超精细相互作用外,还有空穴对三重态激子的解离作用和三重态激子对电子的散射作用的共存,且它们都受单重态激子分裂（singlet fission）的影响.利用Lorentzian和non-Lorentzian经验函数可以对MC进行较好拟合,进一步证实了上述观点.三重态激子解离和电子散射共存这一发现不仅有助于对Rubrene器件中电荷与激发态间相互作用机制的认识,在优化器件性能方面也有一定的指导意义.
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.
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(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Acknowledgements J. X. acknowledges financial support from the National Natural Science Foundation of China （No. 21502147 （J. X.）, No. 21421061 （J. L.）） and the generous start-up funds from Wuhan University of Technology （No. 40122004）.
文摘The cooperative interaction distance measure has been proposed as a novel law pertaining to dialectics of nature, and has been extensively carried out in the design of functional nanomaterials. However, the temporal and spatial dimensions are akin to yin and yang, and thus temporal regulation needs to be accounted for when implementing the above-mentioned principle. Here, we summarize recent advances in temporally and spatially regulated materials and devices. We showcase the temporal regulation of organic semiconductors for organic photovoltaics （OPVs） using the example of exciton lifetime manipulation. As an example of spatial regulation, we consider the distribution of charge carriers in core-shell quantum dot （QD） nanocrystals for modulating their optical properties. Long exciton lifetime can in principle increase the exciton diffussion length, which is desiable for high-efficiency large-area OPV devices. Spatially regulated QDs are highly valuable emitters for light-emitting applications. We aim to show that cooperative spatio-temporal regulation of nanomaterils is of vital importance to the development of functional devices.
基金Supported by the National Natural Science Foundation of China（Nos.21673289, 21273282, 21673288）.
文摘The β-carotene（β-Car） aggregate was prepared by self-assembly in cetyltrimethylammoniuln bromide （CTAB） micelle. The ground state absorption measurement showed that the aggregate has J-type characteristics and resonance Raman spectra gave the intrinsic explanation of molecular interaction in aggregate. Upon excitation at the optical allowed S2 state of aggregate, direct generation of triplet state via singlet fission（SF）mechanism was observed. Excitation dynamics was elucidated by fs-transient absorption spectroscopy and ns-flash photolysis, respectively. The triplet state life time of aggregate was found to be independent of the ambient oxygen molecules.
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.
基金Supported by the National Natural Science Foundation of China(Nos.21273282,21673289,21673288,21173265)the International Cooperation Project Between China and Russia(NSFC-RFBR)(No.21411130185).
文摘The structure and excited state properties of the H- and J-aggregates of the marine carbonyl carotenoid, fucoxanthin(Fx), were studied by various spectroscopic methods, and compared with those of Fx monomers in polar organic solvents. The fluorescent analysis indicated tliat the higher vibronic states of S2 contribute more to populating the S1 state, from which fluorescent emission mainly originates. Resonance Raman and density functional theory calculations confirmed the ‘card-packed' and chead-to-taiF structures of the H- and J-aggregates of Fx, respectively. An fs time-resolved absorption study proved the coexistence of Si and intramolecular charge transfer relaxation pathways upon excitation to the S2 state for both tlie monomers and aggregates.
