Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero...Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.展开更多
We calculate the electronic properties and carrier mobility of perovskite CH3NH3SnI3as a solar cell absorber by using the hybrid functional method. The calculated result shows that the electron and hole mobilities hav...We calculate the electronic properties and carrier mobility of perovskite CH3NH3SnI3as a solar cell absorber by using the hybrid functional method. The calculated result shows that the electron and hole mobilities have anisotropies with a large magnitude of 1.4 × 104cm2·V-1·s-1along the y direction. In view of the huge difference between hole and electron mobilities, the perovskite CH3NH3 Sn I3can be considered as a p-type semiconductor. We also discover a relationship between the effective mass anisotropy and electronic occupation anisotropy. The above results can provide reliable guidance for its experimental applications in electronics and optoelectronics.展开更多
Organolead halide perovskite solar cells have attracted extensive interests in recent years. Thanks to innovations in materials process and technology, the power conversion efficiency (PCE) of perovskites-based solar ...Organolead halide perovskite solar cells have attracted extensive interests in recent years. Thanks to innovations in materials process and technology, the power conversion efficiency (PCE) of perovskites-based solar cells increases from 3.8% to 25.2%[1–4].In evaluating the quality of perovskite materials, a few key photophysical properties such as the lifetime, mobility and diffusion length of photogenerated carriers are usually measured.展开更多
The structural, electronic, and elastic properties of cubic HC(NH2)2PbI3 perovskite are investigated by density functional theory using the Tkatchenko-Scheffler pairwise dispersion scheme. Our relaxed lattice parame...The structural, electronic, and elastic properties of cubic HC(NH2)2PbI3 perovskite are investigated by density functional theory using the Tkatchenko-Scheffler pairwise dispersion scheme. Our relaxed lattice parameters are in agreement with experimental data. The hydrogen bonding between NH2 and I ions is found to have a crucial role in FAPbI3 stability. The first calculated band structure shows that HC(NH2)2PbI3 has a direct bandgap (1.02 eV) at R-point, lower than the bandgap (1.53 eV) of CH3NH3PbI3. The calculated density of states reveals that the strong hybridization of s(Pb)-p(I) orbital in valence band maximum plays an important role in the structural stability. The photo-generated effective electron mass and hole mass at R-point along the R-Γ and R-M directions are estimated to be smaller:me^*=0.06m0 and mh^*=0.08m0 respectively, which are consistent with the values experimentally observed from long range photocarrier transport. The elastic properties are also investigated for the first time, which shows that HC(NH2)2PbI3 is mechanically stable and ductile and has weaker strength of the average chemical bond. This work sheds light on the understanding of applications of HC(NH2)2PbI3 as the perovskite in a planar-heterojunction solar cell light absorber fabricated on flexible polymer substrates.展开更多
The formation of cocrystallization in two various conjugated components may endow the newly formed conjugated cocrystals with multiple functionalities and improved charge transport properties.However,compared to conju...The formation of cocrystallization in two various conjugated components may endow the newly formed conjugated cocrystals with multiple functionalities and improved charge transport properties.However,compared to conjugated small molecules,this strategy is rather limitedly realized in conjugated polymers.Herein,a simple meniscus-assisted solution printing(MASP)strategy is utilized to achieve the cocrystallization in the blends of two conjugated polymers,i.e.,poly(3-hexylthiophene)(P3HT)and poly(3-octylthiophene)(P3OT),and the cocrystalline structures are correlated closely to their charge mobilities.The P3HT/P3OT blends phase separate and crystallize individually in their drop-cast thin films.When subjecting the P3HT/P3OT blended solution to MASP,the confined solvent evaporation between two nearly parallel plates triggers them to cocrystallize progressively when accelerating the moving lower plate.The cocrystallization kinetics and the changes in P3HT/P3OT molecular structures are elucidated.Finally,these different crystalline structures of P3HT/P3OT blends are applied in organic fieldeffect transistors,imparting the cocrystallization-enhanced charge transport than respective P3HT and P3OT crystal domains.Such MASP method can be extended to craft cocrystals of other conjugated polymer blends for their diverse optoelectronic applications.展开更多
Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor(IGBT)power modules.The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation ...Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor(IGBT)power modules.The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation characteristics.This paper focuses on the trap characteristics and electrical properties of the silicone gel,which were rarely studied before.The experiments are performed on the surface potential decay of silicone gel after the charge injection.Then,the energy distributions of electron or hole traps are determined by a double-trap energy level model,which can be fitted by the Gaussian distribution.In addition,the mobilities of positive and negative charges are determined,which are 1.38×10^(-12) m^(2)·V^(-1)·s^(-1) and 1.74×10^(12) m^(2)·V^(-1)·s^(-1),respectively.Furthermore,considering the heat as a byproduct resulting in thermal issues,the temperature-dependence of surface potential decay characteristics are also studied in this paper.When temperature rises,the decay rate of surface potential increases,especially when the temperature is higher than 80℃.Finally,the contrastive analysis illustrates that the trap characteristics of silicone gel are between the trap characteristics in liquid-state material and solid-state material,which supports the phenomenon that silicone gel is more resistive to the sharp edges in power modules.This work can provide a useful reference for the design of encapsulation in high-voltage IGBT power modules.展开更多
This paper reports the synthesis and characteristics of a series of alkyl-substituted planar polymers. The physical properties are carefully tuned to optimize their photovoltaic performance. Depending on the length of...This paper reports the synthesis and characteristics of a series of alkyl-substituted planar polymers. The physical properties are carefully tuned to optimize their photovoltaic performance. Depending on the length of soluble alkyl side chains which modify the structural order and orientation substantially in polymer backbones, the device performance can be improved significantly. The tuning of HOMO energy levels optimized polymers' spectral coverage of absorption and their hole mobility, as well as miscibility with fullerene; all these efforts enhanced polymer solar cell performances. The short- circuit current, Jsc for polymer solar cells was increased by adjusting polymer chain packing ability. It was found that films with well distributed polymer/fullerene interpenetrating network exhibit improved solar cell conversion efficiency. Enhanced efficiency up to 5.8% has been demonstrated. The results provide important insights about the roles of flexile chains in structure-property relationship for the design of new polymers to be used in high efficient solar cells.展开更多
Charge carrier mobility is one of the most significant properties for organic semiconductors. In this work, the electronic structures and charge transport properties of 9,10-bis((E)-2-(pyrid-n-yl)vinyl) (n=2, 3...Charge carrier mobility is one of the most significant properties for organic semiconductors. In this work, the electronic structures and charge transport properties of 9,10-bis((E)-2-(pyrid-n-yl)vinyl) (n=2, 3, 4) anthracene (BP2VA, BP3VA and BP4VA) were investigated via the analysis of the molecular geometry, the reorganization en- ergy, the frontier orbital and density of state, as well as the electronic coupling and the charge mobility. The results indicated that the linkage between 9,10-divinyl anthracene unit and pyridine (ortho-, meta- and para-) influenced not only the intra-molecular conformation (i.e., the reorganization energies), but also the intermolecular interaction (i.e., transfer integrals), and finally the charge mobility of the molecules. It is also found that: (1) The calculated charge mobilties of holes are dozens of times higher than those of electrons for the three molecules. (2) The charge mobilities of hole and electron of the three molecules display the trend: μBP4VA〉μBPZVA〉μBP3VA, and the hole mobility of BP4VA is as high as as-cm^2/(V·s).展开更多
The incorporation of heavy atoms into molecular backbone is an extremely straightforward strategy for fine-tuning the optoelectronic properties of organic semiconductors.However,it is rarely studied in n-type small mo...The incorporation of heavy atoms into molecular backbone is an extremely straightforward strategy for fine-tuning the optoelectronic properties of organic semiconductors.However,it is rarely studied in n-type small molecules.Herein,by selenium substitution of NDI3 HU-DTYM2,two Se-decorated core-expanded naphthalene diimides(NDI)derivatives DTYM-NDI3 HUDSYM(1)and NDI3 HU-DSYM2(2)were synthesized.In comparison with the reference S-containing compound NDI3 HUDTYM2,the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)energy levels of 1 and 2 were fine-tuned with?HOMO of about 0.2 e V,?LUMO of 0.1 e V and the narrowed HOMO-LUMO gaps.More surprisingly,the as-spun organic thin film transistors(OTFTs)based on 1 and 2 both showedμe,satvalues as high as1.0 cm2 V-1 s-1,which are 2-fold higher than that of NDI3 HU-DTYM2 with the same device structure and measurement conditions.In addition,the single crystal OFET devices based on Se-containing compound NDI2 BO-DSYM2 showed a highμe,satvalue of 1.30 cm2 V-1 s-1.The molecular packing of NDI2 BO-DSYM2 in single crystals(two-dimensional supramolecular structure formed by intermolecular Se···Se interactions)is quite different from that of a S-containing compound NDI-DTYM2(one dimensional supramolecular structure formed by intermolecularπ-πstacking).Therefore,the Se substitution can cause dramatic change about molecular stacking model,giving rise to high n-type OTFT performance.Our results demonstrated an effective strategy of the heavy atom effect for designing novel organic semiconductors.展开更多
Large π-conjugated pyrene-phenazine monoimide and bisimides were synthesized by imine condensation reaction. These imides form well ordered 1D nanotapes upon self-assembly in solution. Electrochemical and electric co...Large π-conjugated pyrene-phenazine monoimide and bisimides were synthesized by imine condensation reaction. These imides form well ordered 1D nanotapes upon self-assembly in solution. Electrochemical and electric conductivity measurement reveal it can be served as an n-channel semiconductor with large charge carrier mobility up to 4.1 cm^2 V^-1 s^-1. Both alkylated imides are highly luminescent, and can be quenched via protonization using trifluoroacetic acid, which could be served as potential colorimetric acid sensors.展开更多
基金funded by Australian Research Council discovery project DP140103041Future Fellowship FT160100205
文摘Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.51172067)the Hunan Provincial Natural Science Fund for Distinguished Young Scholars,China(Grant No.13JJ1013)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20130161110036)the New Century Excellent Talents in University,China(Grant No.NCET-12-0171.D)
文摘We calculate the electronic properties and carrier mobility of perovskite CH3NH3SnI3as a solar cell absorber by using the hybrid functional method. The calculated result shows that the electron and hole mobilities have anisotropies with a large magnitude of 1.4 × 104cm2·V-1·s-1along the y direction. In view of the huge difference between hole and electron mobilities, the perovskite CH3NH3 Sn I3can be considered as a p-type semiconductor. We also discover a relationship between the effective mass anisotropy and electronic occupation anisotropy. The above results can provide reliable guidance for its experimental applications in electronics and optoelectronics.
基金supported by the NSFC(21703241)the Youth Innovation Promotion Association CAS(2019188)the DICP I201913。
文摘Organolead halide perovskite solar cells have attracted extensive interests in recent years. Thanks to innovations in materials process and technology, the power conversion efficiency (PCE) of perovskites-based solar cells increases from 3.8% to 25.2%[1–4].In evaluating the quality of perovskite materials, a few key photophysical properties such as the lifetime, mobility and diffusion length of photogenerated carriers are usually measured.
基金supported by the National Natural Science Foundation of China(Grant No.51572219)the Natural Science Foundation of Shaanxi Province,China(Grant No.2015JM1018)+3 种基金the Graduate Innovation Fund of Northwest University of China(Grant No.YJG15007)the Henan Provincial Foundation and Frontier Technology Research Program,China(Grant Nos.2013JCYJ12 and 2013JCYJ13)the Fund from Henan University of Technology,China(Grant No.2014YWQN08)the Natural Science Fund from the Henan Provincial Education Department,China(Grant No.16A140027)
文摘The structural, electronic, and elastic properties of cubic HC(NH2)2PbI3 perovskite are investigated by density functional theory using the Tkatchenko-Scheffler pairwise dispersion scheme. Our relaxed lattice parameters are in agreement with experimental data. The hydrogen bonding between NH2 and I ions is found to have a crucial role in FAPbI3 stability. The first calculated band structure shows that HC(NH2)2PbI3 has a direct bandgap (1.02 eV) at R-point, lower than the bandgap (1.53 eV) of CH3NH3PbI3. The calculated density of states reveals that the strong hybridization of s(Pb)-p(I) orbital in valence band maximum plays an important role in the structural stability. The photo-generated effective electron mass and hole mass at R-point along the R-Γ and R-M directions are estimated to be smaller:me^*=0.06m0 and mh^*=0.08m0 respectively, which are consistent with the values experimentally observed from long range photocarrier transport. The elastic properties are also investigated for the first time, which shows that HC(NH2)2PbI3 is mechanically stable and ductile and has weaker strength of the average chemical bond. This work sheds light on the understanding of applications of HC(NH2)2PbI3 as the perovskite in a planar-heterojunction solar cell light absorber fabricated on flexible polymer substrates.
基金supported by the National Key R&D Program of China(2022YFA1203802 and 2021YFA1202903)the National Natural Science Foundation of China(92264202,61974060 and 61674080)the Innovation and Entrepreneurship Program of Jiangsu Province.
基金financially supported by the National Natural Science Foundation of China(Nos.21922503 and 22173023)Natural Science Foundation of Shanghai(No.21ZR1405800)。
文摘The formation of cocrystallization in two various conjugated components may endow the newly formed conjugated cocrystals with multiple functionalities and improved charge transport properties.However,compared to conjugated small molecules,this strategy is rather limitedly realized in conjugated polymers.Herein,a simple meniscus-assisted solution printing(MASP)strategy is utilized to achieve the cocrystallization in the blends of two conjugated polymers,i.e.,poly(3-hexylthiophene)(P3HT)and poly(3-octylthiophene)(P3OT),and the cocrystalline structures are correlated closely to their charge mobilities.The P3HT/P3OT blends phase separate and crystallize individually in their drop-cast thin films.When subjecting the P3HT/P3OT blended solution to MASP,the confined solvent evaporation between two nearly parallel plates triggers them to cocrystallize progressively when accelerating the moving lower plate.The cocrystallization kinetics and the changes in P3HT/P3OT molecular structures are elucidated.Finally,these different crystalline structures of P3HT/P3OT blends are applied in organic fieldeffect transistors,imparting the cocrystallization-enhanced charge transport than respective P3HT and P3OT crystal domains.Such MASP method can be extended to craft cocrystals of other conjugated polymer blends for their diverse optoelectronic applications.
基金This work was supported by the National Natural Science Foundation of China-the State Grid Corporation Joint Fund for Smart Grid(U1766219)the Fundamental Research Funds for the Central Universities(2019QN120).
文摘Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor(IGBT)power modules.The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation characteristics.This paper focuses on the trap characteristics and electrical properties of the silicone gel,which were rarely studied before.The experiments are performed on the surface potential decay of silicone gel after the charge injection.Then,the energy distributions of electron or hole traps are determined by a double-trap energy level model,which can be fitted by the Gaussian distribution.In addition,the mobilities of positive and negative charges are determined,which are 1.38×10^(-12) m^(2)·V^(-1)·s^(-1) and 1.74×10^(12) m^(2)·V^(-1)·s^(-1),respectively.Furthermore,considering the heat as a byproduct resulting in thermal issues,the temperature-dependence of surface potential decay characteristics are also studied in this paper.When temperature rises,the decay rate of surface potential increases,especially when the temperature is higher than 80℃.Finally,the contrastive analysis illustrates that the trap characteristics of silicone gel are between the trap characteristics in liquid-state material and solid-state material,which supports the phenomenon that silicone gel is more resistive to the sharp edges in power modules.This work can provide a useful reference for the design of encapsulation in high-voltage IGBT power modules.
基金supported by Beijing NOVA Programme(Z131101000413038)Beijing Local College Innovation Team Improve Plan(IDHT20140512)+2 种基金the National Natural Science Foundation of China(91433115,91222203,91233205 and 51222306)the Ministry of Science and Technology of China(2013CB933403 and 2013CB933504)the University of Copenhagen
基金financially supported by the Postdoctoral Starting Foundation of Henan Normal University(01026500105)Young Scientists Foundation of Henan Normal University(01026400061)Henan Province basic and frontier technology research projects(1323004100247)
文摘This paper reports the synthesis and characteristics of a series of alkyl-substituted planar polymers. The physical properties are carefully tuned to optimize their photovoltaic performance. Depending on the length of soluble alkyl side chains which modify the structural order and orientation substantially in polymer backbones, the device performance can be improved significantly. The tuning of HOMO energy levels optimized polymers' spectral coverage of absorption and their hole mobility, as well as miscibility with fullerene; all these efforts enhanced polymer solar cell performances. The short- circuit current, Jsc for polymer solar cells was increased by adjusting polymer chain packing ability. It was found that films with well distributed polymer/fullerene interpenetrating network exhibit improved solar cell conversion efficiency. Enhanced efficiency up to 5.8% has been demonstrated. The results provide important insights about the roles of flexile chains in structure-property relationship for the design of new polymers to be used in high efficient solar cells.
文摘Charge carrier mobility is one of the most significant properties for organic semiconductors. In this work, the electronic structures and charge transport properties of 9,10-bis((E)-2-(pyrid-n-yl)vinyl) (n=2, 3, 4) anthracene (BP2VA, BP3VA and BP4VA) were investigated via the analysis of the molecular geometry, the reorganization en- ergy, the frontier orbital and density of state, as well as the electronic coupling and the charge mobility. The results indicated that the linkage between 9,10-divinyl anthracene unit and pyridine (ortho-, meta- and para-) influenced not only the intra-molecular conformation (i.e., the reorganization energies), but also the intermolecular interaction (i.e., transfer integrals), and finally the charge mobility of the molecules. It is also found that: (1) The calculated charge mobilties of holes are dozens of times higher than those of electrons for the three molecules. (2) The charge mobilities of hole and electron of the three molecules display the trend: μBP4VA〉μBPZVA〉μBP3VA, and the hole mobility of BP4VA is as high as as-cm^2/(V·s).
基金the National Natural Science Foundation of China(21522209,21790362,21502218)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB12010100)the Science and Technology Commission of Shanghai Municipality(19XD1424700,18JC1410600)。
文摘The incorporation of heavy atoms into molecular backbone is an extremely straightforward strategy for fine-tuning the optoelectronic properties of organic semiconductors.However,it is rarely studied in n-type small molecules.Herein,by selenium substitution of NDI3 HU-DTYM2,two Se-decorated core-expanded naphthalene diimides(NDI)derivatives DTYM-NDI3 HUDSYM(1)and NDI3 HU-DSYM2(2)were synthesized.In comparison with the reference S-containing compound NDI3 HUDTYM2,the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)energy levels of 1 and 2 were fine-tuned with?HOMO of about 0.2 e V,?LUMO of 0.1 e V and the narrowed HOMO-LUMO gaps.More surprisingly,the as-spun organic thin film transistors(OTFTs)based on 1 and 2 both showedμe,satvalues as high as1.0 cm2 V-1 s-1,which are 2-fold higher than that of NDI3 HU-DTYM2 with the same device structure and measurement conditions.In addition,the single crystal OFET devices based on Se-containing compound NDI2 BO-DSYM2 showed a highμe,satvalue of 1.30 cm2 V-1 s-1.The molecular packing of NDI2 BO-DSYM2 in single crystals(two-dimensional supramolecular structure formed by intermolecular Se···Se interactions)is quite different from that of a S-containing compound NDI-DTYM2(one dimensional supramolecular structure formed by intermolecularπ-πstacking).Therefore,the Se substitution can cause dramatic change about molecular stacking model,giving rise to high n-type OTFT performance.Our results demonstrated an effective strategy of the heavy atom effect for designing novel organic semiconductors.
基金supported by the National Natural Science Foundation of China(Nos. 51522303, 21602154)National Key R&D Program of China (No. 2017YFA0207500)the Thousand Youth Talents Plan
文摘Large π-conjugated pyrene-phenazine monoimide and bisimides were synthesized by imine condensation reaction. These imides form well ordered 1D nanotapes upon self-assembly in solution. Electrochemical and electric conductivity measurement reveal it can be served as an n-channel semiconductor with large charge carrier mobility up to 4.1 cm^2 V^-1 s^-1. Both alkylated imides are highly luminescent, and can be quenched via protonization using trifluoroacetic acid, which could be served as potential colorimetric acid sensors.