Recently, ZrTe5 has received a lot of attention as it exhibits various topological phases, such as weak and strong topological insulators, a Dirac semimetal, a three-dimensional quantum Hall state, and a quantum spin ...Recently, ZrTe5 has received a lot of attention as it exhibits various topological phases, such as weak and strong topological insulators, a Dirac semimetal, a three-dimensional quantum Hall state, and a quantum spin Hall insulator in the monolayer limit. While most of studies have been focused on the three-dimensional bulk material, it is highly desired to obtain nanostructured materials due to their advantages in device applications. We report the synthesis and characterizations of ZrTe5 nanoribbons. Via a silicon-assisted chemical vapor transport method, long nanoribbons with thickness as thin as 20 nm can be grown. The growth rate is over an order of magnitude faster than the previous method for the bulk crystals.Moreover, transport studies show that the nanoribbons are of low unintentional doping and high carrier mobility, over30000 cm2/V·s, which enable reliable determination of the Berry phase of π in the ac plane from quantum oscillations. Our method holds great potential in growth of high quality ultra-thin nanostructures of ZrTe5.展开更多
Waterborne coatings often delaminate and settle during long-term storage,requiring the addition of thickeners.The effects of nanofibrillated cellulose(NFC)and the commonly used thickener,hydroxyethyl cellulose(HEC),on...Waterborne coatings often delaminate and settle during long-term storage,requiring the addition of thickeners.The effects of nanofibrillated cellulose(NFC)and the commonly used thickener,hydroxyethyl cellulose(HEC),on the storage stability of waterborne coatings were compared in this study.The morphology of NFC was characterized using infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The rotational viscosity and rheological properties of the waterborne coatings with NFC and HEC were tested.Stationary settling experiments were also conducted at different temperatures to compare the difference of NFC and HEC on improving the storage stability of the waterborne coatings.The results showed that the waterborne coating with NFC exhibited pseudoplastic fluid characteristics;a small addition of NFC can achieve the same improvement effect on the storage stability of waterborne coatings as HEC.Further,the improvement effect of NFC was not affected by temperature.The waterborne coating with NFC still exhibited good storage stability at high temperatures,which was significantly superior to that of HEC.Therefore,NFC is a feasible agent for improving the prolonged storage stability and warming-induced delamination of waterborne coatings.展开更多
To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-co...To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.展开更多
Flexible transparent electrodes(FTEs) with robust mechanical stability are crucial for the industrial application of flexible organic solar cells(OSCs). However, their production remains challenging owing to the diffi...Flexible transparent electrodes(FTEs) with robust mechanical stability are crucial for the industrial application of flexible organic solar cells(OSCs). However, their production remains challenging owing to the difficulty in balancing the conductivity,transmittance, and adhesion of FTEs to substrates. Herein, we present the so-called “reinforced concrete” strategy which finetunes the structure of silver nanowires(Ag NWs)-based FTEs with polydopamine(PDA) possessing good adhesion properties and moderate reducibility. The PDA reduces Ag+to form silver nanoparticles(Ag NPs) which grow like “rivets” at the Ag NW junction sites;PDA stabilizes the Ag NW skeleton and improves the adhesion between the Ag NWs and polyethylene terephthalate(PET) substrate and interface layer. The obtained Ag NW:PDA:Ag NP FTE exhibits excellent optoelectronic properties and high mechanical stability. The resulting flexible OSCs exhibit 17.07% efficiency, high flexibility during 10,000 bending test cycles, and robust peeling stability. In addition, this “reinforced concrete”-like FTE provides great advantages for the production of large-area flexible OSCs, thereby paving a new way toward their commercial application.展开更多
Perovskite solar cells(pero-SCs)performance is essentially limited by severe non-radiative losses and ion migration.Although numerous strategies have been proposed,challenges remain in the basic understanding of their...Perovskite solar cells(pero-SCs)performance is essentially limited by severe non-radiative losses and ion migration.Although numerous strategies have been proposed,challenges remain in the basic understanding of their origins.Here,we report a dielectric-screening-enhancement effect for perovskite defects by using organic semiconductors with finely tuned molecular structures from the atoms level.Our method produced various perovskite films with high dielectric constant values,reduced charge capture regions,suppressed ion migration,and it provides an efficient charge transport pathway for suppressing non-radiative recombination beyond the passivation effect.The resulting pero-SCs showed a promising power conversion efficiency(PCE)of 23.35%with a high open-circuit voltage(1.22 V);and the 1-cm^(2) pero-SCs maintained an excellent PCE(21.93%),showing feasibility for scalable fabrication.The robust operational and thermal stabilities revealed that this method paved a new way to understand the degradation mechanism of pero-SCs,promoting the efficiency,stability and scaled fabrication of the pero-SCs.展开更多
基金National Key Research and Development Program of China(Grant Nos.2016YFA0300600,2016YFA0300802,2013CB932904,and 2016YFA0202500)the National Natural Science Foundation of China(Grant Nos.11574005,11774009,and 11234001).
文摘Recently, ZrTe5 has received a lot of attention as it exhibits various topological phases, such as weak and strong topological insulators, a Dirac semimetal, a three-dimensional quantum Hall state, and a quantum spin Hall insulator in the monolayer limit. While most of studies have been focused on the three-dimensional bulk material, it is highly desired to obtain nanostructured materials due to their advantages in device applications. We report the synthesis and characterizations of ZrTe5 nanoribbons. Via a silicon-assisted chemical vapor transport method, long nanoribbons with thickness as thin as 20 nm can be grown. The growth rate is over an order of magnitude faster than the previous method for the bulk crystals.Moreover, transport studies show that the nanoribbons are of low unintentional doping and high carrier mobility, over30000 cm2/V·s, which enable reliable determination of the Berry phase of π in the ac plane from quantum oscillations. Our method holds great potential in growth of high quality ultra-thin nanostructures of ZrTe5.
文摘Waterborne coatings often delaminate and settle during long-term storage,requiring the addition of thickeners.The effects of nanofibrillated cellulose(NFC)and the commonly used thickener,hydroxyethyl cellulose(HEC),on the storage stability of waterborne coatings were compared in this study.The morphology of NFC was characterized using infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The rotational viscosity and rheological properties of the waterborne coatings with NFC and HEC were tested.Stationary settling experiments were also conducted at different temperatures to compare the difference of NFC and HEC on improving the storage stability of the waterborne coatings.The results showed that the waterborne coating with NFC exhibited pseudoplastic fluid characteristics;a small addition of NFC can achieve the same improvement effect on the storage stability of waterborne coatings as HEC.Further,the improvement effect of NFC was not affected by temperature.The waterborne coating with NFC still exhibited good storage stability at high temperatures,which was significantly superior to that of HEC.Therefore,NFC is a feasible agent for improving the prolonged storage stability and warming-induced delamination of waterborne coatings.
文摘To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.
基金supported by the National Natural Science Foundation of China (51922074, 22075194, 51820105003)the National Key Research and Development Program of China(2020YFB1506400)+3 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (20KJA430010)the Tang Scholarthe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)Collaborative Innovation Center of Suzhou Nano Science and Technology。
文摘Flexible transparent electrodes(FTEs) with robust mechanical stability are crucial for the industrial application of flexible organic solar cells(OSCs). However, their production remains challenging owing to the difficulty in balancing the conductivity,transmittance, and adhesion of FTEs to substrates. Herein, we present the so-called “reinforced concrete” strategy which finetunes the structure of silver nanowires(Ag NWs)-based FTEs with polydopamine(PDA) possessing good adhesion properties and moderate reducibility. The PDA reduces Ag+to form silver nanoparticles(Ag NPs) which grow like “rivets” at the Ag NW junction sites;PDA stabilizes the Ag NW skeleton and improves the adhesion between the Ag NWs and polyethylene terephthalate(PET) substrate and interface layer. The obtained Ag NW:PDA:Ag NP FTE exhibits excellent optoelectronic properties and high mechanical stability. The resulting flexible OSCs exhibit 17.07% efficiency, high flexibility during 10,000 bending test cycles, and robust peeling stability. In addition, this “reinforced concrete”-like FTE provides great advantages for the production of large-area flexible OSCs, thereby paving a new way toward their commercial application.
基金supported by the National Key Research and Development Program of China(2020YFB1506400)the National Natural Science Foundation of China(51922074,22075194,and 51820105003)+3 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(20KJA430010)the Tang Scholarthe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Collaborative Innovation Center of Suzhou Nano Science and Technology。
文摘Perovskite solar cells(pero-SCs)performance is essentially limited by severe non-radiative losses and ion migration.Although numerous strategies have been proposed,challenges remain in the basic understanding of their origins.Here,we report a dielectric-screening-enhancement effect for perovskite defects by using organic semiconductors with finely tuned molecular structures from the atoms level.Our method produced various perovskite films with high dielectric constant values,reduced charge capture regions,suppressed ion migration,and it provides an efficient charge transport pathway for suppressing non-radiative recombination beyond the passivation effect.The resulting pero-SCs showed a promising power conversion efficiency(PCE)of 23.35%with a high open-circuit voltage(1.22 V);and the 1-cm^(2) pero-SCs maintained an excellent PCE(21.93%),showing feasibility for scalable fabrication.The robust operational and thermal stabilities revealed that this method paved a new way to understand the degradation mechanism of pero-SCs,promoting the efficiency,stability and scaled fabrication of the pero-SCs.
