Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the sol...Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide（NDTI） based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering（GIWAXS） measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10-3 cm2 V/-1 s-1 for NDTI-1 to 4.70×10-2 cm2 V/-1 s-1 for NDTI-2 and 9.27×10-2 cm2 V/-1 s-1 for NDTI-3,which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited redshifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies（PCEs） than the other two polymers（beside the comparable result of PTB7-Th:NDTI-3 combination） as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.展开更多
The influences of the anthesis date and the fruiting branch positions on parameters of cotton fiber quality and super-molecular structure were studied. Fiber quality parameters, such as cotton fiber length, micronair,...The influences of the anthesis date and the fruiting branch positions on parameters of cotton fiber quality and super-molecular structure were studied. Fiber quality parameters, such as cotton fiber length, micronair, maturity and fiber strength deteriorated with postponing the anthesis date and decreasing temperature. When anthesis happened on the same date, the fruiting branch positions affected the fiber quality parameters, and the fiber quality parameters of the lower portion turned out to be higher than that of the upper portion, although the difference was insignificant. The super-molecular structure of the lower portion turned out to be superior to that of the upper portion at the early anthesis date and high temperature, which is in accordance with what was mentioned above, but the fruiting branch positions did not affect the impact of the anthesis date on the super-molecular structure.展开更多
Different objects in Chinese paintings contain rich cultural connotations. Segmenting and extracting different objects in Chinese paintings through technical methods is an effective way to enhance cultural added value...Different objects in Chinese paintings contain rich cultural connotations. Segmenting and extracting different objects in Chinese paintings through technical methods is an effective way to enhance cultural added value and activate cultural resources.Although the existing deep learning methods can extract multi-level features for instance segmentation, the location relationship features of instances are not fully utilized, resulting in poor segmentation results for the traditional Chinese painting(TCP) instance segmentation. In this paper, a novel TCP image instance segmentation algorithm based on the integration of spatial structure characteristics(SSC) was proposed, and is called SSC-Net. Firstly, considering the characteristics of TCP images, such as the gradual color blending and discontinuous contour lines, an instance information entropy composed of color entropy, formed by regional variance, and contour entropy, formed by contour point regression is proposed. Then, aiming at the problem that the existing network structure is difficult to fully consider the location relationship features of instances in TCP images, based on the residual neural network(ResNet) structure, a Chinese painting instance segmentation network framework composed of mask branch and position branch that can integrate spatial structure features is proposed. Finally, the color entropy and contour entropy are input into the mask branch and position branch of the SSC-Net structure respectively, so as to realize the instance segmentation of TCP. The quantitative and qualitative experiments on the challenging TCP database show that, compared with the state-of-the-art algorithms in the same category, the SSC-Net achieves good experimental results with average precision(AP) of 53.89% and 25.8 frame per second(FPS). The segmentation results meet the practical application requirements.展开更多
基金supported by the National Key Research and Development Program of China (2017YFA0206600)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (QYZDB-SSW-SLH033)the National Natural Science Foundation of China (51673048, 21875052)
文摘Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide（NDTI） based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering（GIWAXS） measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10-3 cm2 V/-1 s-1 for NDTI-1 to 4.70×10-2 cm2 V/-1 s-1 for NDTI-2 and 9.27×10-2 cm2 V/-1 s-1 for NDTI-3,which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited redshifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies（PCEs） than the other two polymers（beside the comparable result of PTB7-Th:NDTI-3 combination） as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.
文摘The influences of the anthesis date and the fruiting branch positions on parameters of cotton fiber quality and super-molecular structure were studied. Fiber quality parameters, such as cotton fiber length, micronair, maturity and fiber strength deteriorated with postponing the anthesis date and decreasing temperature. When anthesis happened on the same date, the fruiting branch positions affected the fiber quality parameters, and the fiber quality parameters of the lower portion turned out to be higher than that of the upper portion, although the difference was insignificant. The super-molecular structure of the lower portion turned out to be superior to that of the upper portion at the early anthesis date and high temperature, which is in accordance with what was mentioned above, but the fruiting branch positions did not affect the impact of the anthesis date on the super-molecular structure.
基金supported by the National Key Research and Development Program of China (2021YFF0901700)。
文摘Different objects in Chinese paintings contain rich cultural connotations. Segmenting and extracting different objects in Chinese paintings through technical methods is an effective way to enhance cultural added value and activate cultural resources.Although the existing deep learning methods can extract multi-level features for instance segmentation, the location relationship features of instances are not fully utilized, resulting in poor segmentation results for the traditional Chinese painting(TCP) instance segmentation. In this paper, a novel TCP image instance segmentation algorithm based on the integration of spatial structure characteristics(SSC) was proposed, and is called SSC-Net. Firstly, considering the characteristics of TCP images, such as the gradual color blending and discontinuous contour lines, an instance information entropy composed of color entropy, formed by regional variance, and contour entropy, formed by contour point regression is proposed. Then, aiming at the problem that the existing network structure is difficult to fully consider the location relationship features of instances in TCP images, based on the residual neural network(ResNet) structure, a Chinese painting instance segmentation network framework composed of mask branch and position branch that can integrate spatial structure features is proposed. Finally, the color entropy and contour entropy are input into the mask branch and position branch of the SSC-Net structure respectively, so as to realize the instance segmentation of TCP. The quantitative and qualitative experiments on the challenging TCP database show that, compared with the state-of-the-art algorithms in the same category, the SSC-Net achieves good experimental results with average precision(AP) of 53.89% and 25.8 frame per second(FPS). The segmentation results meet the practical application requirements.
