Two D-π-A dyes based on fused acenes（carbazole, cyclopenta[2,1-b：3,4-b＇]dithiophene（CPDT） and dithieno[3,2-b：2＇,3＇-d]pyrrole（DTP）） were synthesized, characterized using UV-vis absorption spectroscopy and e...Two D-π-A dyes based on fused acenes（carbazole, cyclopenta[2,1-b：3,4-b＇]dithiophene（CPDT） and dithieno[3,2-b：2＇,3＇-d]pyrrole（DTP）） were synthesized, characterized using UV-vis absorption spectroscopy and electrochemistry, density function theory（DFT） calculations, and used as sensitizers in dyesensitized solar cells（DSSCs）. The two sensitizers were compared thoroughly over physicochemical properties and DSSC performance. Although the DTP dye has slightly blue-shifted and weaker incident photon-to-collected electron（IPCE） conversion efficiency responses, the much increased open-circuit photovoltage values and improved charge-transfer kinetics relative to the CPDT systems result in superior power conversion efficiencies. This work reveals the potential of DTP as a bridge in the design of sensitizers.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
Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties.Nevertheless,the poor ambient stability of longer acenes has hampered the investigation ...Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties.Nevertheless,the poor ambient stability of longer acenes has hampered the investigation of their physicochemical properties and potential applications.The incorporation of main group elements into the acene backbones provides a viable strategy to enhance the stability,and meanwhile,generates a new family of heteroatom-doped acenes(namely heteroacenes)with modified properties and functions.In particular,boron-containing acenes represent an attractive class of heteroacenes owing to the existence of vacant p orbital of boron,which endows theπ-conjugated systems with appealing features,such as Lewis acidity,electron-accepting capability,stimuli-responsivity,and adjustable photophysical properties.During the past decade,significant progress has been achieved in the synthesis and applications of boron-containing acenes,but a focused review on this topic has been elusive.Here,we summarize the recent advances in the studies on boron-containing acenes,covering their synthesis,intriguing properties,and various applications in electroluminescence and electronic devices,as well as in biosensors,etc.We hope that this timely review will stimulate new research interest in this unique family of materials and promote their optoelectronic applications.展开更多
Manufacturing parts in nanoscale and investigating their properties has involved some limitations, and in some cases it is practically impossible;therefore, scholars have recently focused on micro-parts in natural sca...Manufacturing parts in nanoscale and investigating their properties has involved some limitations, and in some cases it is practically impossible;therefore, scholars have recently focused on micro-parts in natural scale, which has led to the advent of the field of nanostructures. Phenacenes with formula C4n+2H2n+4 are a family of organic molecules which have received a lot of attention in nanoscale. However, investigating the thermodynamic properties is highly expensive, especially when there are more than 6 loops. The present study was conducted in order to predict the thermodynamic properties of phenacenes family bu using Topological Indices Method (TIM). Topological index is a numeral molecular graph which is referred to as molecular graph. This number indicates some molecular properties. One of the topological indices is RRR which is investigated and measured in phenacenes family. Afterwards, by calculating Heat of Formation and Gibbs Energy for some members of this family and comparing them with data provided by valid articles, we could propose an appropriate model to predict some thermodynamic properties of this family.展开更多
文摘Two D-π-A dyes based on fused acenes（carbazole, cyclopenta[2,1-b：3,4-b＇]dithiophene（CPDT） and dithieno[3,2-b：2＇,3＇-d]pyrrole（DTP）） were synthesized, characterized using UV-vis absorption spectroscopy and electrochemistry, density function theory（DFT） calculations, and used as sensitizers in dyesensitized solar cells（DSSCs）. The two sensitizers were compared thoroughly over physicochemical properties and DSSC performance. Although the DTP dye has slightly blue-shifted and weaker incident photon-to-collected electron（IPCE） conversion efficiency responses, the much increased open-circuit photovoltage values and improved charge-transfer kinetics relative to the CPDT systems result in superior power conversion efficiencies. This work reveals the potential of DTP as a bridge in the design of sensitizers.
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.
基金financial support from the National Natural Science Foundation of China(Nos.92256304 and 22071120)the National Key R&D Program of China(2020YFA0711500)the Fundamental Research Funds for the Central Universities.
文摘Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties.Nevertheless,the poor ambient stability of longer acenes has hampered the investigation of their physicochemical properties and potential applications.The incorporation of main group elements into the acene backbones provides a viable strategy to enhance the stability,and meanwhile,generates a new family of heteroatom-doped acenes(namely heteroacenes)with modified properties and functions.In particular,boron-containing acenes represent an attractive class of heteroacenes owing to the existence of vacant p orbital of boron,which endows theπ-conjugated systems with appealing features,such as Lewis acidity,electron-accepting capability,stimuli-responsivity,and adjustable photophysical properties.During the past decade,significant progress has been achieved in the synthesis and applications of boron-containing acenes,but a focused review on this topic has been elusive.Here,we summarize the recent advances in the studies on boron-containing acenes,covering their synthesis,intriguing properties,and various applications in electroluminescence and electronic devices,as well as in biosensors,etc.We hope that this timely review will stimulate new research interest in this unique family of materials and promote their optoelectronic applications.
文摘Manufacturing parts in nanoscale and investigating their properties has involved some limitations, and in some cases it is practically impossible;therefore, scholars have recently focused on micro-parts in natural scale, which has led to the advent of the field of nanostructures. Phenacenes with formula C4n+2H2n+4 are a family of organic molecules which have received a lot of attention in nanoscale. However, investigating the thermodynamic properties is highly expensive, especially when there are more than 6 loops. The present study was conducted in order to predict the thermodynamic properties of phenacenes family bu using Topological Indices Method (TIM). Topological index is a numeral molecular graph which is referred to as molecular graph. This number indicates some molecular properties. One of the topological indices is RRR which is investigated and measured in phenacenes family. Afterwards, by calculating Heat of Formation and Gibbs Energy for some members of this family and comparing them with data provided by valid articles, we could propose an appropriate model to predict some thermodynamic properties of this family.
