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2015 Volume 74 Issue 3
2015, 74(3): 251-258
doi: 10.6023/A15090606
Abstract:
Designing and synthesizing novel polymer electron-donor materials of polymer-based solar cells (PSCs) with the high photovoltaic performance is an important and hot research field of organic electronics. In the current work, taking the 4,8-di(thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (DBDT) as the electron-rich unit and the 3,6-di(thiophen-2-yl)pyrrolo[3, 4-c]pyrrole-1,4(2H,5H)-dione (DPP) as the electron-deficient one, a new donor material (PDBDTDPP) of PSCs has been designed. Then, with the [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an electron acceptor, the geometries, electronic properties, optical absorption properties, intramolecular and intermolecular reorganization energies, exciton binding energies, charge transfer integrals, and the rates of exciton dissociation and charge recombination for PC61BM-DBDTDPPn=1,2,3,∞ systems have been theoretically investigated by means of density functional theory (DFT) calculations coupled with the incoherent Marcus-Hush charge transfer model and some extensive multidimensional visualization techniques. In addition, the linear regression analysis has been done to explore the relationship between the above properties and the repeating unit. Calculated results show that the designed donor polymer possesses a good planar geometry, the low-lying the highest occupied molecular orbital (HOMO) level, strong and wide optical absorption in ultraviolet-visible band, large exciton binding energy (1.365 eV), and the relatively small intramolecular reorganization energies companying with the exciton dissociation (0.152 eV) and charge recombination (0.314 eV) processes. Furthermore, our theoretical study also reveals that in the donor-acceptor surface, the exciton dissociation rate is as high as 1.073×1014 s-1, while the charge recombination rate is only 1.797×108 s-1. The former is as six orders of magnitude large as the latter, which denotes that there is quite high exciton dissociation efficiency in the studied donor-acceptor surface. In brief, our theoretical results clearly indicate that PDBDTDPP should be a very promising electron-donating material, and is worth of making further device research by experiments. In addition, this study also shows that theoretical investigations not only can promote a deeper understanding for the connection between the chemical structures and the optical/electronic properties of organic compounds, but also can provide some valuable references for the rational design of novel donor-acceptor systems.
Designing and synthesizing novel polymer electron-donor materials of polymer-based solar cells (PSCs) with the high photovoltaic performance is an important and hot research field of organic electronics. In the current work, taking the 4,8-di(thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (DBDT) as the electron-rich unit and the 3,6-di(thiophen-2-yl)pyrrolo[3, 4-c]pyrrole-1,4(2H,5H)-dione (DPP) as the electron-deficient one, a new donor material (PDBDTDPP) of PSCs has been designed. Then, with the [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an electron acceptor, the geometries, electronic properties, optical absorption properties, intramolecular and intermolecular reorganization energies, exciton binding energies, charge transfer integrals, and the rates of exciton dissociation and charge recombination for PC61BM-DBDTDPPn=1,2,3,∞ systems have been theoretically investigated by means of density functional theory (DFT) calculations coupled with the incoherent Marcus-Hush charge transfer model and some extensive multidimensional visualization techniques. In addition, the linear regression analysis has been done to explore the relationship between the above properties and the repeating unit. Calculated results show that the designed donor polymer possesses a good planar geometry, the low-lying the highest occupied molecular orbital (HOMO) level, strong and wide optical absorption in ultraviolet-visible band, large exciton binding energy (1.365 eV), and the relatively small intramolecular reorganization energies companying with the exciton dissociation (0.152 eV) and charge recombination (0.314 eV) processes. Furthermore, our theoretical study also reveals that in the donor-acceptor surface, the exciton dissociation rate is as high as 1.073×1014 s-1, while the charge recombination rate is only 1.797×108 s-1. The former is as six orders of magnitude large as the latter, which denotes that there is quite high exciton dissociation efficiency in the studied donor-acceptor surface. In brief, our theoretical results clearly indicate that PDBDTDPP should be a very promising electron-donating material, and is worth of making further device research by experiments. In addition, this study also shows that theoretical investigations not only can promote a deeper understanding for the connection between the chemical structures and the optical/electronic properties of organic compounds, but also can provide some valuable references for the rational design of novel donor-acceptor systems.
2015, 74(3): 259-264
doi: 10.6023/A15100655
Abstract:
Hollow nano-material is one of the hot researches in recent years because of special optical, electrical, magnetic and catalytic properties. Polymer nanotube (PNT) is a polymer nano-material with tubular structure. Template method is an effective preparation method for tubular polymer nano-materials. In this study, we have developed a simple technique for the fabrication of polymer nanotubes by using self-assembled metal organic nanotube (MONT) as a template and multiple amine and acid as precursor molecules. An amphiphilic molecule (N-tetradecanoic glycylglycine, 1) was firstly synthesized by the coupling reaction of N-tetradecanoic acid and glycylglycine ethyl ester under the function of 1-ethyl-3-(3-dimethylamin-opropyl)carbodiimide hydrochloride (EDC·HCl), followed by a hydration process. The amphiphilic molecule 1 was successfully obtained in high yields. MONT was then prepared by the self-assembly of 1 with copper(Ⅱ) nitrate in methanol. A solution of copper(Ⅱ) nitrate in water was slowly added into a solution of 1 in methanol. The mixed solution was stirred for 24 h at room temperature and MONT was obtained by filtration, washing with water and freeze-dry. And finally, template reactions were carried out as follows: a certain amount of MONT was dispersed in tetrahydrofuran (THF), and then the multiple amine was added to complex with copper ions on the surface of MONT. The mixed solution was stirred for 3 h at room temperature and a coated layer formed on the surface of MONT. The coated layer on the nanotube surface was further cross-linked by an activated ester of citric acid. Finally, the self-assembled template was removed by hot filtration and the PNTs with good dispersibility in water were obtained. The surface topography, composition and structure of PNTs were characterized by scanning electron microscope (SEM), scanning transmission electron microscopy (STEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that up to 80% cross-linked products form PNTs when the amount of multiple amines is 0.4 molar equivalent of MONT. The lengths of PNTs are about 500 nm~3 μm, inner diameters are 60~100 nm and outer diameters are 80~120 nm.
Hollow nano-material is one of the hot researches in recent years because of special optical, electrical, magnetic and catalytic properties. Polymer nanotube (PNT) is a polymer nano-material with tubular structure. Template method is an effective preparation method for tubular polymer nano-materials. In this study, we have developed a simple technique for the fabrication of polymer nanotubes by using self-assembled metal organic nanotube (MONT) as a template and multiple amine and acid as precursor molecules. An amphiphilic molecule (N-tetradecanoic glycylglycine, 1) was firstly synthesized by the coupling reaction of N-tetradecanoic acid and glycylglycine ethyl ester under the function of 1-ethyl-3-(3-dimethylamin-opropyl)carbodiimide hydrochloride (EDC·HCl), followed by a hydration process. The amphiphilic molecule 1 was successfully obtained in high yields. MONT was then prepared by the self-assembly of 1 with copper(Ⅱ) nitrate in methanol. A solution of copper(Ⅱ) nitrate in water was slowly added into a solution of 1 in methanol. The mixed solution was stirred for 24 h at room temperature and MONT was obtained by filtration, washing with water and freeze-dry. And finally, template reactions were carried out as follows: a certain amount of MONT was dispersed in tetrahydrofuran (THF), and then the multiple amine was added to complex with copper ions on the surface of MONT. The mixed solution was stirred for 3 h at room temperature and a coated layer formed on the surface of MONT. The coated layer on the nanotube surface was further cross-linked by an activated ester of citric acid. Finally, the self-assembled template was removed by hot filtration and the PNTs with good dispersibility in water were obtained. The surface topography, composition and structure of PNTs were characterized by scanning electron microscope (SEM), scanning transmission electron microscopy (STEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that up to 80% cross-linked products form PNTs when the amount of multiple amines is 0.4 molar equivalent of MONT. The lengths of PNTs are about 500 nm~3 μm, inner diameters are 60~100 nm and outer diameters are 80~120 nm.
2015, 74(3): 285-292
doi: 10.6023/A15100641
Abstract:
Geometries of complexes HXeBr…C6H5X (X=H, CH3, NH2, N(CH3)2, NHCH3, OH, OCH3, CN, F, Cl, Br, I, COOH, SO3H, CF3) and its monomers are optimized with MP2/aug-cc-pVDZ (aug-cc-pVDZ-PP for Xe and I). The aug-cc-pVDZ-PP is a small core pseudopotential basis set. It ignores 28 electrons for Xe and I atoms. Two types of weak interactions, π…H bond and bifurcated hydrogen bonds, are analyzed in detail. The effects of substituting group of the benzene ring on the weak interaction energies are investigated. Their effects on π…H bond are different from that on bifurcated hydrogen bonds. As for the complexes with π…H bond, electron withdrawing groups reduce the interaction energies while electron donating groups increase the interaction energies. However, for the complexes with bifurcated hydrogen bonds, electron withdrawing groups increase the interaction energies while electron-donating groups decrease the interaction energies. The effects of substituting groups on geometrical parameters of HXeBr are also analyzed. As for 14 complexes of HXeBr…C6H5X with bifurcated hydrogen bonds, it is found that their weak interaction energies have very good linear relationships with dipole moments of C6H5X, bond length changes of Xe—Br and H—Xe bonds, vibrational frequency changes of H—Xe bonds, and the sum of two interpenetration distances of Van der Waals surfaces of bromine and two hydrogen atoms which are connected to the bromine atom by hydrogen bonds. It is also found that the weak interaction energies of 14 complexes above have very good linear relationships with the sum of electron densities (ρ), the sum of ∇2ρ and the sum of electrostatic potentials at two critical points of bifurcated hydrogen bonds, and with the electron density, ∇2ρ and the electrostatic potential at the ring critical point which is inside a ring formed by the bifurcated hydrogen bonds and two carbon atoms of the benzene ring. As for the complexes with bifurcated hydrogen bonds, the weak interaction energies between the monomers can be understood approximately as dipole-dipole interaction.
Geometries of complexes HXeBr…C6H5X (X=H, CH3, NH2, N(CH3)2, NHCH3, OH, OCH3, CN, F, Cl, Br, I, COOH, SO3H, CF3) and its monomers are optimized with MP2/aug-cc-pVDZ (aug-cc-pVDZ-PP for Xe and I). The aug-cc-pVDZ-PP is a small core pseudopotential basis set. It ignores 28 electrons for Xe and I atoms. Two types of weak interactions, π…H bond and bifurcated hydrogen bonds, are analyzed in detail. The effects of substituting group of the benzene ring on the weak interaction energies are investigated. Their effects on π…H bond are different from that on bifurcated hydrogen bonds. As for the complexes with π…H bond, electron withdrawing groups reduce the interaction energies while electron donating groups increase the interaction energies. However, for the complexes with bifurcated hydrogen bonds, electron withdrawing groups increase the interaction energies while electron-donating groups decrease the interaction energies. The effects of substituting groups on geometrical parameters of HXeBr are also analyzed. As for 14 complexes of HXeBr…C6H5X with bifurcated hydrogen bonds, it is found that their weak interaction energies have very good linear relationships with dipole moments of C6H5X, bond length changes of Xe—Br and H—Xe bonds, vibrational frequency changes of H—Xe bonds, and the sum of two interpenetration distances of Van der Waals surfaces of bromine and two hydrogen atoms which are connected to the bromine atom by hydrogen bonds. It is also found that the weak interaction energies of 14 complexes above have very good linear relationships with the sum of electron densities (ρ), the sum of ∇2ρ and the sum of electrostatic potentials at two critical points of bifurcated hydrogen bonds, and with the electron density, ∇2ρ and the electrostatic potential at the ring critical point which is inside a ring formed by the bifurcated hydrogen bonds and two carbon atoms of the benzene ring. As for the complexes with bifurcated hydrogen bonds, the weak interaction energies between the monomers can be understood approximately as dipole-dipole interaction.
