Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was c...Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.展开更多
Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model. With the interchain coupling enhancing,it takes longer time for the electron added to the syst...Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model. With the interchain coupling enhancing,it takes longer time for the electron added to the system to induce a localized polaron state. Beyond a certain strength of the interchain coupling,the electron evolves into a two-dimensional delocalized polaron state. Dynamical simulations suggest that the well-ordered organic molecule systems with two-dimensional polarons exhibit higher mobilities than the systems with intrachain localized polarons,as also suggested by earlier experiments.展开更多
The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratio...The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratios of solid-state O - PPV/ PEO (polyethylene oxide ) blends, as well as by comparing PL spectra for dilute solution and solid state pristine O - PPV. The solid film of O - PPV/PEO is prepared to investigate the interaction between polymers. The O - PPV molecules are dispersed into PEO which is used as a inert material in order to change the interaction between O - PPV. In the O -PPV/PEO blends, it is found that the PL spectra excited by 300nm for different concentration ratios are different. There are three peaks in the PL spectra of 1: 100 and 1: 200 (O - PPV/PEO) blends, and the relative intensities of peaks at 500nm and 460nm gradually decrease with lowering the concentrations of O - PPV. There leaves one peak at 416nm when the ratio of O - PPV to PEO is below 1: 300, and PL shape does not change any longer. The results show that the solid-state O - PPV emission arises from interchain charge-transfer states due to interchain effects.According to the absorption and photoluminescence spectra of the solid films, it is also believed that there are types of localized and delocalized states in conjugated polymers. The two types of states have different effects on charge-transfer state in different concentrations of solid films.展开更多
采用拓展紧束缚Su-Schrieffer-Heeger(SSH)模型,研究了链间耦合对反式聚乙炔多链体系中电子极化子再激发态的晶格位形、净电荷密度、局域能级波函数和态密度的影响.结果发现:对于两条链体系,当链间耦合很小(t⊥≤0.01 e V)时,注入到系...采用拓展紧束缚Su-Schrieffer-Heeger(SSH)模型,研究了链间耦合对反式聚乙炔多链体系中电子极化子再激发态的晶格位形、净电荷密度、局域能级波函数和态密度的影响.结果发现:对于两条链体系,当链间耦合很小(t⊥≤0.01 e V)时,注入到系统中的电子只会在第一条链上诱发产生一个晶格缺陷,形成电子极化子再激发态,这和单链体系是一致,而第二条链仍是二聚化基态.随着链间耦合的增大,第一条链上缺陷的局域度减少而第二条链上的缺陷局域度相应增加,直至两条链上的位形相同;对于多条链(5条链和6条链)体系,当耦合很小(t⊥≤0.05 e V)时,电子极化子再激发态也只会存在于一条链上,当链间耦合较强时,极化子再激发态会在链间层次性地扩展开来,并不会出现多条链位形相同;从两条链的能级图上可以看到随着链间耦合t⊥的增大,体系的带隙不断的增大和电子态密度显示的是完全吻合的,体系的导电性减弱.通过分析两条链体系在t⊥=0 e V和t⊥=0.1 e V的能级态密度,发现链间耦合越强,则中间局域能级的态密度越小,最后没有中间局域态.展开更多
Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. Th...Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. The preparation process was analyzed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. A reducing agent, 2-mercaptoethanol, was used to remove disulfide bonds and analyze the structure of the bonds involved between α chains in some types of collagens. The use of delayed reducing methods resulted in the difference between α1 （Ⅲ） and α1 （ Ⅰ ） chains in a mixture containing type Ⅰ and Ⅲ collagens. The structure of disulfide bonds among α chains exists potentially in type V collagen prepared from the pepsin-treatment extraction at 4 ℃, which differs from type Ⅲ collagen in relation to the locations of disulfide bonds. Compared with pepsin-treated collagen at 4 ℃, the relative molecular weights of α1 （V） and α2 （V） chains treated at room temperature decrease by 4.6% and 6.0%, respectively. It is concluded that type Ⅰ Ⅲ and Ⅴ collagens can be prepared from bovine dermis and cornea by the use of pepsin treatment, salt precipitation and dialysis. The interchain disulfide bonds lie potentially near the edges of termini of type V collagen molecules in extracellular matrix, and a small number of interchain crosslinks exist in type V collagen.展开更多
The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are...The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are taken into account simultaneously. One is similar of that of deformation potential and the other is of polaron type. For simplicity, the 2D crystal model is considered. The renormalized phonon spectrum and the phonon polarization operator are calculated in the random phase approximation for different temperatures. The effects of interchain interaction on renormalized acoustic phonons and on the Peierls critical temperature are analyzed.展开更多
We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most ...We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most important hole-phonon interaction mechanisms. One is similar to that of deformation potential and the other is of polaron type. The scattering on defects is also considered and it is crucial for the explanation of the transition. The phonon polarization operator and the renormalized phonon spectrum are calculated in the random phase approximation for different temperatures applying the method of Green functions. We show that the transition is of Peierls type. The effect of lattice distortion on the dispersion of renormalized acoustic phonons is analyzed.展开更多
The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crysta...The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crystal physical model is applied that considers two of the most important hole-phonon interactions. The first interaction describes the deformation potential and the second one is of polaron type. In the presented physical model, the interaction of carriers with the structural defects is taken into account. This is crucial for the explanation of the transition. The renormalized phonon spectrum is calculated in the random phase approximation for different temperatures applying the method of Green functions. The renormalized phonon frequencies for different temperatures are presented in two cases. In the first case the interaction between TTT chains is neglected. In the second one, this interaction is taken into account. Computer simulations for the 3D physical model of the TTT<sub>2</sub>I<sub>3</sub> crystal are performed for different values of dimensionless Fermi momentum <em>k</em><sub>F</sub>, that is determined by variation of carrier concentration. It is shown that the transition is of Peierls type and strongly depends on iodine concentration. Finally, the Peierls critical temperature was determined.展开更多
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(2022R1F1A1065586,2019R1A6A1A11053838)the GIST Research Institute(GRI)APRI grant funded by the GIST in 2022.
文摘Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.
文摘Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model. With the interchain coupling enhancing,it takes longer time for the electron added to the system to induce a localized polaron state. Beyond a certain strength of the interchain coupling,the electron evolves into a two-dimensional delocalized polaron state. Dynamical simulations suggest that the well-ordered organic molecule systems with two-dimensional polarons exhibit higher mobilities than the systems with intrachain localized polarons,as also suggested by earlier experiments.
文摘The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratios of solid-state O - PPV/ PEO (polyethylene oxide ) blends, as well as by comparing PL spectra for dilute solution and solid state pristine O - PPV. The solid film of O - PPV/PEO is prepared to investigate the interaction between polymers. The O - PPV molecules are dispersed into PEO which is used as a inert material in order to change the interaction between O - PPV. In the O -PPV/PEO blends, it is found that the PL spectra excited by 300nm for different concentration ratios are different. There are three peaks in the PL spectra of 1: 100 and 1: 200 (O - PPV/PEO) blends, and the relative intensities of peaks at 500nm and 460nm gradually decrease with lowering the concentrations of O - PPV. There leaves one peak at 416nm when the ratio of O - PPV to PEO is below 1: 300, and PL shape does not change any longer. The results show that the solid-state O - PPV emission arises from interchain charge-transfer states due to interchain effects.According to the absorption and photoluminescence spectra of the solid films, it is also believed that there are types of localized and delocalized states in conjugated polymers. The two types of states have different effects on charge-transfer state in different concentrations of solid films.
文摘采用拓展紧束缚Su-Schrieffer-Heeger(SSH)模型,研究了链间耦合对反式聚乙炔多链体系中电子极化子再激发态的晶格位形、净电荷密度、局域能级波函数和态密度的影响.结果发现:对于两条链体系,当链间耦合很小(t⊥≤0.01 e V)时,注入到系统中的电子只会在第一条链上诱发产生一个晶格缺陷,形成电子极化子再激发态,这和单链体系是一致,而第二条链仍是二聚化基态.随着链间耦合的增大,第一条链上缺陷的局域度减少而第二条链上的缺陷局域度相应增加,直至两条链上的位形相同;对于多条链(5条链和6条链)体系,当耦合很小(t⊥≤0.05 e V)时,电子极化子再激发态也只会存在于一条链上,当链间耦合较强时,极化子再激发态会在链间层次性地扩展开来,并不会出现多条链位形相同;从两条链的能级图上可以看到随着链间耦合t⊥的增大,体系的带隙不断的增大和电子态密度显示的是完全吻合的,体系的导电性减弱.通过分析两条链体系在t⊥=0 e V和t⊥=0.1 e V的能级态密度,发现链间耦合越强,则中间局域能级的态密度越小,最后没有中间局域态.
基金Supported by National Natural Science Foundation of China (No.30970724)Natural Science Foundation of Tianjin (No.08JCYBJC03400)
文摘Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. The preparation process was analyzed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. A reducing agent, 2-mercaptoethanol, was used to remove disulfide bonds and analyze the structure of the bonds involved between α chains in some types of collagens. The use of delayed reducing methods resulted in the difference between α1 （Ⅲ） and α1 （ Ⅰ ） chains in a mixture containing type Ⅰ and Ⅲ collagens. The structure of disulfide bonds among α chains exists potentially in type V collagen prepared from the pepsin-treatment extraction at 4 ℃, which differs from type Ⅲ collagen in relation to the locations of disulfide bonds. Compared with pepsin-treated collagen at 4 ℃, the relative molecular weights of α1 （V） and α2 （V） chains treated at room temperature decrease by 4.6% and 6.0%, respectively. It is concluded that type Ⅰ Ⅲ and Ⅴ collagens can be prepared from bovine dermis and cornea by the use of pepsin treatment, salt precipitation and dialysis. The interchain disulfide bonds lie potentially near the edges of termini of type V collagen molecules in extracellular matrix, and a small number of interchain crosslinks exist in type V collagen.
文摘The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are taken into account simultaneously. One is similar of that of deformation potential and the other is of polaron type. For simplicity, the 2D crystal model is considered. The renormalized phonon spectrum and the phonon polarization operator are calculated in the random phase approximation for different temperatures. The effects of interchain interaction on renormalized acoustic phonons and on the Peierls critical temperature are analyzed.
文摘We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most important hole-phonon interaction mechanisms. One is similar to that of deformation potential and the other is of polaron type. The scattering on defects is also considered and it is crucial for the explanation of the transition. The phonon polarization operator and the renormalized phonon spectrum are calculated in the random phase approximation for different temperatures applying the method of Green functions. We show that the transition is of Peierls type. The effect of lattice distortion on the dispersion of renormalized acoustic phonons is analyzed.
文摘The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crystal physical model is applied that considers two of the most important hole-phonon interactions. The first interaction describes the deformation potential and the second one is of polaron type. In the presented physical model, the interaction of carriers with the structural defects is taken into account. This is crucial for the explanation of the transition. The renormalized phonon spectrum is calculated in the random phase approximation for different temperatures applying the method of Green functions. The renormalized phonon frequencies for different temperatures are presented in two cases. In the first case the interaction between TTT chains is neglected. In the second one, this interaction is taken into account. Computer simulations for the 3D physical model of the TTT<sub>2</sub>I<sub>3</sub> crystal are performed for different values of dimensionless Fermi momentum <em>k</em><sub>F</sub>, that is determined by variation of carrier concentration. It is shown that the transition is of Peierls type and strongly depends on iodine concentration. Finally, the Peierls critical temperature was determined.
