分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: The cathode interlayer is essential to bulk heterojunction polymer solar cells (PSCs). As we all know, most of the organic interfacial materials are amino derivatives, including neutral amine derivatives and ammonium derivatives. Herein, a non-amino small molecule, TBT-a, with sulfonate anionic pendants was synthesized and interface modification was investigated. The PSC with TBT-a as the cathode interlayer exhibited a high power conversion efficiency of 8.68%. We found that the TBT-a interlayer simultaneously enhanced all the device parameters, probably by inducing an effective interface dipole, altering the optical distribution, and enhancing the electron mobility. These results indicated that sulfonate interfacial materials could play a similar role as amine-based interfacial materials in interface modification.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: We report a doping method to enhance the performance of solution processed planar heterojunction perovskite solar cells. By doping a small percentage (3 wt%) of polyethylenimine (PEI) as additive into the PCBM electron transport layer of an inverted perovskite solar cell, which led to significant enhancements of power conversion efficiency from (5.9 ` 0.2) % to (10.4 ` 0.2) %. The AFM images show that the PEI doped PCBM layer can help to form a high quality, homogeneous and compact electron transporting layer on the rough CH3NH3PbI3 layer, which results in enhanced hole blocking ability and reduced leakage current at the interfaces between the CH3NH3PbI3, PCBM films and the top Al electrode. Organic field-effect transistors (OFETs) measurements reveal that the addition of 1–3 wt% PEI into PCBM layer can improve device performance without any negative effect on the electron transport property of PCBM. Steady-state PL analysis shows that the electron-rich PEI may also act as an effective interfacial modifier to passivate the trap states at the perovskite surface or crystal boundaries and to avoid the undesired charge recombination often observed in perovskite solar cells. PEI will also improve performance as a cathode interfacial modifier because the PCE of the device with PEI deposited between PCBM and Al is superior to the device without PEI. This work demonstrated that amine- containing polymer materials can be used as an efficient dual functional additive in perovskite solar cells. This study provides an efficient way of developing highly efficient CH3NH3PbI3-based perovskite solar cells.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Highly flexible and transparent film heaters (TFHs) with superior mechanical and thermal stability were fabricated by embedding silver nanowires (AgNWs) into transparent polyimide (PI) films using a solution coating method. The fabricated AgNW/PI hybrid TFHs exhibited higher heating temperatures ($96 C) with lower input voltage ($6 V), shorter response time (T < 40 s), and lower power consumption (160.6 C cm2 W 1) than ITO/FTO heaters, as well as stability after repeated use. The AgNW/PI hybrid TFHs also showed excellent resistance to bending. After undergoing outer bending for a 1000 times, the change of sheet resistance was less than 18%. The effective embedment of the AgNW network in the surface of the transparent PI film not only decreased the surface roughness (Rrms < 1 nm) but also enhanced the resistance against oxidation and moisture. Potential applications of the AgNW/PI TFHs in window defogging and thermochromics are demonstrated.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: MoS2 nanoflowers consisting of nanosheets are synthesized by a one-step hydrothermal method. The interlayer distances of the MoS2 nanosheets, accompanied with the changes of crystallinity, defects, specific surface areas as well as the thickness of the MoS2 nanosheets, can be well controlled via simply altering hydrothermal reaction temperatures. The effect of interlayer distances on the lithium storage capability for lithium ion batteries is investigated. The results show that MoS2 synthesized under 200 C with an interlayer distance of 0.65 nm exhibit the highest lithium storage capacity and the best rate capability, showing a high discharge capacity of 814.2 mA h g 1 at 100 mA g 1 after 50 cycles and as highas652.2mAhg 1 and547.3mAhg 1 atcurrentdensitiesof1Ag 1 and2Ag 1 at25 C, respectively. The excellent lithium storage properties of the resultant MoS2 nanoflowers are attributed to its controllable optimized interplanar distance with good crystallinity, appropriate surface area and defects as well as thickness of the nanosheets.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Aluminum alloys with novel binary anti-corrosion structures on the surface showing superhydrophobic properties were fabricated via chemical etching, anodic oxidation and chemical modification. Surface morphologies and chemical elements of the as-prepared films were investigated by Fourier transform infrared spectrometer, scanning electron microscopy and confocal laser scanning microscope. Surface wettability was investigated by the contact angle meter. Manipulation of surface morphology by anodic oxidation current density and the influence of surface chemical modification on the wettability were investigated. The anti-corrosion properties of the as-prepared films were characterized using an electrochemistry workstation. The results showed that surface water contact angle could reach 156 after chemical modification when the current density of anodic oxidation was 5 A dm 2. The corrosion potential (Ecorr) was positively increased from 1189 mV for bare Al alloys to 304 mV for the samples anodized at 5 A dm 2. The synergetic effect between the protective properties of air trapped in a low adhesion superhydrophobic surface and good barrier properties of the barrier layer of anodic oxidation film was remarkably enhanced the corrosion resistance of aluminum alloys. Influences of the anodic oxidation current density and the self-assembled films on the anti-corrosion performance were discussed in detail.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Stretchable and flexible conductive polymers have aroused great interest recently because of their applications in the fields of novel electronics, such as smart textiles, artificial electronic skin, flexible electronic displays, etc. In this work, stretchable and flexible conductive thermoplastic polyurethane (TPU)/graphene composite foams have been developed by water vapour induced phase separation. The as-prepared TPU/graphene composite foams exhibited a lower modulus, larger elongation at break, and lower hysteresis during a cycle tensile test than a TPU/graphene composite did. It is expected that the improved elasticity of the TPU/graphene composite foams was caused by the deformation of cells, which partially offset the deformation of the TPU matrix. In addition, the cell walls divided the whole composites into many small parts, which could further restrain plastic deformation of hard segment domains under deformation.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Linear and hyperbranched poly(azomethine)s (PAMs)-based on tri- phenylamine moieties are synthesized and used as the functioning layers in the Ta/PAM/Pt resistive switching memory devices. Com- parably, the hyperbranched PAM with isotropic architecture and semi-crystalline nature shows enhanced memory behaviors with more uniform distribution of the HRS and LRS resistances.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Compared with the rapid progress on bio-based thermoplastics, research on bio-based thermosetting resins should have attracted much more attention, considering that they will have a bright future. In this paper, the current research progress on bio-based thermosetting resins is reviewed. We pay special attention to the synthesis and investigation of properties of epoxies and unsaturated polyesters derived from renewable plant oil, cardanol, rosin acid, lignin, glycerol, gallic acid, furan, isosorbide, itaconic acid, etc. This mini review gives an overall perspective for bio-based thermosets. © 2015 Society of Chemical Industry
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Tungsten substituted mesoporous FDU-12 (W-FDU-12) catalysts were synthesized by a one-pot hydrothermal process using F127 as the structure directing agent. The studies of TEM, SAXS and BET illustrated that the highly ordered mesoporous structure of FDU-12 was maintained in the doped W-FDU-12 samples. XPS studies revealed that a high concentration of W5+ species appeared in doped W-FDU-12 catalysts whereas supported WO3/FDU-12 and WO3/SiO2 catalysts only contained W6+ species. Tandem catalytic conversion of 1-butene and ethene to propene through isomerization of 1-butene to 2-butene and consecutive cross metathesis of 2-butene and ethene in a fixed-bed reactor at different temperatures and atmospheric pressure was used to evaluate the catalytic performance of the W-FDU-12 catalyst, combined with MgO. The catalytic results showed that the doped W-FDU-12 illustrated a superior catalytic performance relative to the supported WO3/FDU-12 and WO3/SiO2 catalysts. The higher metathesis activity of W-FDU-12 catalysts can be ascribed to the good dispersion of W species and the incorporation of W species into the framework of FDU-12, forming a substantial amount of W5+, which was beneficial for the cross metathesis of 2-butene and ethene to propene.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: The thermoelectric properties of two-dimensional graphyne sheets are investigated by using first- principles calculations and the Boltzmann transport equation method. The electronic structure indicates a semiconducting phase for graphyne, compared with the metallic phase of graphene. Consequently, the obtained Seebeck coefficient and the power factor of graphyne are much higher than those of graphene. The calculated phonon mean free path for graphene is 866 nm, which is in good agreement with the experimental value of 775 nm. Meanwhile the phonon mean free path of graphyne is only 60 nm, leading to two order lower thermal conductivity than graphene. We show that the low thermal conductivity of graphyne is due to its mixed sp/sp2 bonding. Our calculations show that the optimized ZT values of graphyne sheets can reach 5.3 at intermediate temperature by appropriate doping.