Circularly polarized luminescence(CPL)and two-photon absorption(TPA)materials have garnered considerable attentions due to their minimal energy loss and superior optical penetration[1,2].However,the current challenge ...Circularly polarized luminescence(CPL)and two-photon absorption(TPA)materials have garnered considerable attentions due to their minimal energy loss and superior optical penetration[1,2].However,the current challenge lies in the absence of well-developed strategies for designing materials that combine these two exceptional optical properties.展开更多
The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the ...The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the framework of the polarization continuum model. Particular emphasis was put on the characterization of solvent effects on the molecular geometrical structures and geometric distortion, which were measured by the bond-length-alternation parameter. The π centres in the compounds are seen to play a decisive role in increasing the TPA cross section and nonlinear optical properties. All studied molecules have relatively strong TPA characteristics, while the alkyne π-bridging ones yield larger TPA cross sections.展开更多
We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse ...We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse with a plasma and one or multiple photon beams supplied by intense lasers.Owing to nonlinear effects,two-or multiphoton absorption dominates over the conventional multistep one-photon process for an optimized γ flash.Moreover,this nonlinear effect can be greatly enhanced with the help of externally supplied low-energy photons coming from another laser.These low-energy photons act such that the effective cross-section experienced by the γ photons becomes tunable,growing with the intensity I_(0) of the beam.Assuming I_(0)~10^(18) W·cm^(-2) for the photon beam,an effective cross-section as large as 10^(-21)-10^(-28) cm^(2) for the γ photons can be achieved.Thus,with state-of-the-art 10 PW laser facilities,the yields from two-photon absorption can reach 10^(6)-10^(9) isomers per shot for selected states that are separated from their ground state by E2 transitions.Similar yields for transitions with higher multipolarities can be accommodated by multiphoton absorption with additional photons provided.展开更多
Since the 1990s,femtosecond laser two-photon absorption(TPA),which enables point-by-point photopolymerization,has been a tool for making threedimensional(3D)microstructures.Approximately 10 years later,Kawata et al.im...Since the 1990s,femtosecond laser two-photon absorption(TPA),which enables point-by-point photopolymerization,has been a tool for making threedimensional(3D)microstructures.Approximately 10 years later,Kawata et al.improved the spatial resolution of TPA fabrication to120 nm,far beyond the diffraction limit of the 780 nm laser source.1 The essential mechanism of this nanoscale fabrication lies in the nonlinear effect,in which TPA-induced photopolymerization occurs only in the vicinity of the focal spot.展开更多
CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the perfo...CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the performance of solar cells.For conventional singlejunction cells,the theoretical maximum power conversion efficiency is capped at 33%,a constraint known as the detailed balance limit.Realizing the full potential of PVs requires developing novel strategies to overcome this fundamental obstacle.This Account describes the photon-management capabilities of acenes and addresses these fundamental losses enroute toward enhancing PV performances.For high-energy photons that exceed the semiconductor’s bandgap energy,singlet fission(SF)is a down-conversion pathway to mitigate thermalization losses.SF is a process in organic materials,in which a singlet excited state is split into two independent triplet excited states,effectively doubling the number of charge carriers.Pentacenes stand out among acenes due to their exergonic nature of SF.Numerous molecular pentacene dimers have been synthesized to elucidate the relationship between structure and enhancing SF efficiency.A broader light-harvesting range of SF materials is realized by covalently attaching complementary absorbing energy donors to set up energy donor−acceptor conjugates.Förster resonance energy transfer(FRET)is operative in these energy donor-acceptor conjugates,effectively extending the absorption of SF materials,as the energy donor efficiently transfers its absorbed excitation energy to the energy acceptor.Our studies on various binding motifs show that FRET efficiency depends not only on parameters like the energy donor−acceptor distance and spectral overlap but also on subtle factors such as the alignment of transition dipoles,which significantly affect the energy transfer dynamics and efficiency.Turning to low-energy photons,triplet−triplet annihilation up-conversion(TTA-UC)provides a means of light up-conversion and,thereby,the reduction of sub-bandgap losses.In TTA-UC,a singlet excited state that is potent enough to generate charge carriers is formed by combining two triplet excitons.It is effectively the reverse process of SF.The higher triplet energy of tetracene and an endergonic SF renders them highly effective for TTA-UC.We focus on various tetracene-based systems that maximize TTA-UC efficiency.Besides TTA-UC,two-photon absorption(TPA)is yet another mechanism to leverage below-bandgap photons.It is a nonlinear optical(NLO)process,and acenes reveal NLO properties that are essential for extending light absorption into the near-infrared and still powering SF.We demonstrate in our proof-of-concept studies how TPA further broadens the application potential of acenes for PV systems.The strategies outlined in this Account illustrate that acenes are valuable for addressing mechanistic losses in conventional solar cells.In the final section,we examine light storage following SF by means of interfacial electron transfer.Efficient charge-injection powered by SF materials still requires more research before being implemented in large-scale PV designs.Overall,the advances discussed in this Account not only highlight the pivotal role of acenes as model systems to investigate photon down-and up-conversion processes but also paint a promising picture that more efficient solar energy conversion schemes exceeding the detailed-balance limit can be realized by implementing these materials.展开更多
基金supported by NSFC(22271282)the Self-deployment Project Research Program of Haixi Institutes,Chinese Academy of Sciences with the grant number of CXZX-2022-JQ04.
文摘Circularly polarized luminescence(CPL)and two-photon absorption(TPA)materials have garnered considerable attentions due to their minimal energy loss and superior optical penetration[1,2].However,the current challenge lies in the absence of well-developed strategies for designing materials that combine these two exceptional optical properties.
文摘The present work concerns the study of solvent effects on the geometrical structures, as well as one- and two-photon absorption （TPA） processes, for two series of alkyne and alkene π-bridging molecules, within the framework of the polarization continuum model. Particular emphasis was put on the characterization of solvent effects on the molecular geometrical structures and geometric distortion, which were measured by the bond-length-alternation parameter. The π centres in the compounds are seen to play a decisive role in increasing the TPA cross section and nonlinear optical properties. All studied molecules have relatively strong TPA characteristics, while the alkyne π-bridging ones yield larger TPA cross sections.
基金supported by the Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase Ⅱ,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund—the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)the Romanian Ministry of Research and Innovation:PN23210105(Phase 2,the Program Nucleu),ELI-RO grants Proiectul ELI-RO/RDI_2024_AMAP,ELI-RO_RDI_2024_LaLuThe,ELIRO_RDI_2024_SPARC+4 种基金ELI10/01.10.2020 of the Romanian Governmentthe European Union,the Romanian Governmentthe Health Program,within the project“Medical Applications of High-Power Lasers—Dr.LASER”SMIS Code:326475the IOSIN funds for research infrastructures of national interest.
文摘We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse with a plasma and one or multiple photon beams supplied by intense lasers.Owing to nonlinear effects,two-or multiphoton absorption dominates over the conventional multistep one-photon process for an optimized γ flash.Moreover,this nonlinear effect can be greatly enhanced with the help of externally supplied low-energy photons coming from another laser.These low-energy photons act such that the effective cross-section experienced by the γ photons becomes tunable,growing with the intensity I_(0) of the beam.Assuming I_(0)~10^(18) W·cm^(-2) for the photon beam,an effective cross-section as large as 10^(-21)-10^(-28) cm^(2) for the γ photons can be achieved.Thus,with state-of-the-art 10 PW laser facilities,the yields from two-photon absorption can reach 10^(6)-10^(9) isomers per shot for selected states that are separated from their ground state by E2 transitions.Similar yields for transitions with higher multipolarities can be accommodated by multiphoton absorption with additional photons provided.
基金supported by the National Key R&D Program of China(no.2022YFB4600400)the National Natural Science Foundation of China(nos.T2325014,62205174,and 623B2042).
文摘Since the 1990s,femtosecond laser two-photon absorption(TPA),which enables point-by-point photopolymerization,has been a tool for making threedimensional(3D)microstructures.Approximately 10 years later,Kawata et al.improved the spatial resolution of TPA fabrication to120 nm,far beyond the diffraction limit of the 780 nm laser source.1 The essential mechanism of this nanoscale fabrication lies in the nonlinear effect,in which TPA-induced photopolymerization occurs only in the vicinity of the focal spot.
文摘CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the performance of solar cells.For conventional singlejunction cells,the theoretical maximum power conversion efficiency is capped at 33%,a constraint known as the detailed balance limit.Realizing the full potential of PVs requires developing novel strategies to overcome this fundamental obstacle.This Account describes the photon-management capabilities of acenes and addresses these fundamental losses enroute toward enhancing PV performances.For high-energy photons that exceed the semiconductor’s bandgap energy,singlet fission(SF)is a down-conversion pathway to mitigate thermalization losses.SF is a process in organic materials,in which a singlet excited state is split into two independent triplet excited states,effectively doubling the number of charge carriers.Pentacenes stand out among acenes due to their exergonic nature of SF.Numerous molecular pentacene dimers have been synthesized to elucidate the relationship between structure and enhancing SF efficiency.A broader light-harvesting range of SF materials is realized by covalently attaching complementary absorbing energy donors to set up energy donor−acceptor conjugates.Förster resonance energy transfer(FRET)is operative in these energy donor-acceptor conjugates,effectively extending the absorption of SF materials,as the energy donor efficiently transfers its absorbed excitation energy to the energy acceptor.Our studies on various binding motifs show that FRET efficiency depends not only on parameters like the energy donor−acceptor distance and spectral overlap but also on subtle factors such as the alignment of transition dipoles,which significantly affect the energy transfer dynamics and efficiency.Turning to low-energy photons,triplet−triplet annihilation up-conversion(TTA-UC)provides a means of light up-conversion and,thereby,the reduction of sub-bandgap losses.In TTA-UC,a singlet excited state that is potent enough to generate charge carriers is formed by combining two triplet excitons.It is effectively the reverse process of SF.The higher triplet energy of tetracene and an endergonic SF renders them highly effective for TTA-UC.We focus on various tetracene-based systems that maximize TTA-UC efficiency.Besides TTA-UC,two-photon absorption(TPA)is yet another mechanism to leverage below-bandgap photons.It is a nonlinear optical(NLO)process,and acenes reveal NLO properties that are essential for extending light absorption into the near-infrared and still powering SF.We demonstrate in our proof-of-concept studies how TPA further broadens the application potential of acenes for PV systems.The strategies outlined in this Account illustrate that acenes are valuable for addressing mechanistic losses in conventional solar cells.In the final section,we examine light storage following SF by means of interfacial electron transfer.Efficient charge-injection powered by SF materials still requires more research before being implemented in large-scale PV designs.Overall,the advances discussed in this Account not only highlight the pivotal role of acenes as model systems to investigate photon down-and up-conversion processes but also paint a promising picture that more efficient solar energy conversion schemes exceeding the detailed-balance limit can be realized by implementing these materials.
