The intermolecular interaction determines the photophysical properties of the organic aggregates,which are critical to the performance of organic photovoltaics.Here,excitonic coupling,an important intermolecular inter...The intermolecular interaction determines the photophysical properties of the organic aggregates,which are critical to the performance of organic photovoltaics.Here,excitonic coupling,an important intermolecular interaction in organic aggregates,between theπ-stacking graphene quantum dots is studied by using transient absorption spectroscopy.We find that the spectral evolution of the ground state bleach arises from the dynamic variation of the excitonic coupling in the excitedπ-stacks.According to the spectral simulations,we demonstrate that the kinetics of the vibronic peak can be exploited as a probe to measure the dynamics of excitonic coupling in the excitedπ-stacks.展开更多
We have investigated the self-assembly and light emission properties of organic α- sexithiophene （α-6T） molecules on Ag（100） under different coverage by scanning tunneling microscopy （STM）. At very low coverag...We have investigated the self-assembly and light emission properties of organic α- sexithiophene （α-6T） molecules on Ag（100） under different coverage by scanning tunneling microscopy （STM）. At very low coverage, the α-6T molecules form a unique enantiomer by grouping four molecules into a windmill supermolecular structure. As the coverage is increased,α-6T molecules tend to pack side by side into a denser stripe structure. Further increase of the coverage will lead to the layer-by-layer growth of molecules on Ag（100） with the lower-layer stripe pattern serving as a template. Molecular fluorescence for α-6T molecules on Ag（100） at a coverage of five monolayers has been detected by light excitations, which indicates a well decoupled electronic states for the top-layer α-6T molecules. However, the STM induced luminescent spectra for the same sample reveal only plasmonic-like emission. The absence of intramolecular fluorescence in this case suggests that the electronic decoupling is not a sufficient condition for generating photon emission from molecules. For intramolecular fluorescence to occur, the orientation of the dynamic dipole moment of molecules and the energy-level alignment at the molecule-metal interface are also important so that molecules can be effectively excited through efficient dipolar coupling with local plasmons and by injecting holes into the molecules.展开更多
基金supported by the National Natural Science Foundation of China (No.22175145 and No.21771155)
文摘The intermolecular interaction determines the photophysical properties of the organic aggregates,which are critical to the performance of organic photovoltaics.Here,excitonic coupling,an important intermolecular interaction in organic aggregates,between theπ-stacking graphene quantum dots is studied by using transient absorption spectroscopy.We find that the spectral evolution of the ground state bleach arises from the dynamic variation of the excitonic coupling in the excitedπ-stacks.According to the spectral simulations,we demonstrate that the kinetics of the vibronic peak can be exploited as a probe to measure the dynamics of excitonic coupling in the excitedπ-stacks.
基金supported by the Ministry of Science and Technology of China through the 973 program(Grants 2013CB834703,2015CB65502 and 2013CB933503)the National Natural Science Foundation of China(Grants 21473214,21290191 and 91233105)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant XDB12020200)~~
基金Author to whom correspondence should be addressed. E-mail： zcdong@ustc.edu.cn, FAX： ＋86-551-3600103 This work was supported by the National Basic Research Program of China （No.2006CB922003 and No.2011CB921402）, the Chinese Academy of Sciences （No.KJCX2.YW.H06）, and the National Natural Science Foundation of China （No.91021004, No.10574117, and No.10974186）.
文摘We have investigated the self-assembly and light emission properties of organic α- sexithiophene （α-6T） molecules on Ag（100） under different coverage by scanning tunneling microscopy （STM）. At very low coverage, the α-6T molecules form a unique enantiomer by grouping four molecules into a windmill supermolecular structure. As the coverage is increased,α-6T molecules tend to pack side by side into a denser stripe structure. Further increase of the coverage will lead to the layer-by-layer growth of molecules on Ag（100） with the lower-layer stripe pattern serving as a template. Molecular fluorescence for α-6T molecules on Ag（100） at a coverage of five monolayers has been detected by light excitations, which indicates a well decoupled electronic states for the top-layer α-6T molecules. However, the STM induced luminescent spectra for the same sample reveal only plasmonic-like emission. The absence of intramolecular fluorescence in this case suggests that the electronic decoupling is not a sufficient condition for generating photon emission from molecules. For intramolecular fluorescence to occur, the orientation of the dynamic dipole moment of molecules and the energy-level alignment at the molecule-metal interface are also important so that molecules can be effectively excited through efficient dipolar coupling with local plasmons and by injecting holes into the molecules.
