Competition between Exceptionally Long‐Range Alkyl Sidechain Ordering and Backbone Ordering in Semiconducting Polymers and Its Impact on Electronic and Optoelectronic Properties

Intra‐ and intermolecular ordering greatly impacts the electronic and optoelectronic properties of semiconducting polymers. The interrelationship between ordering of alkyl sidechains and conjugated backbones has yet to be fully detailed, despite much prior effort. Here, the discovery of a highly ordered alkyl sidechain phase in six representative semiconducting polymers, determined from distinct spectroscopic and diffraction signatures, is reported. The sidechain ordering exhibits unusually large coherence lengths (≥70 nm), induces torsional/twisting backbone disorder, and results in a vertically multilayered nanostructure with ordered sidechain layers alternating with disordered backbone layers. Calorimetry and in situ variable temperature scattering measurements in a model system poly{4‐(5‐(4,8‐bis(3‐butylnonyl)‐6‐methylbenzo[1,2‐b:4,5‐b′]dithiophen‐2‐yl)thiophen‐2‐yl)‐2‐(2‐butyloctyl)‐5,6‐difluoro‐7‐(5‐methylthiophen‐2‐yl)‐2H‐benzo[d][1,2,3]triazole} (PBnDT‐FTAZ) clearly delineate this competition of ordering that prevents simultaneous long‐range order of both moieties. The long‐range sidechain ordering can be exploited as a transient state to fabricate PBnDT‐FTAZ films with an atypical edge‐on texture and 2.5× improved field‐effect transistor mobility. The observed influence of ordering between the moieties implies that improved molecular design can produce synergistic rather than destructive ordering effects. Given the large sidechain coherence lengths observed, such synergistic ordering should greatly improve the coherence length of backbone ordering and thereby improve electronic and optoelectronic properties such as charge transport and exciton diffusion lengths.     

Tacky Elastomers to Enable Tear‐Resistant and Autonomous Self‐Healing Semiconductor Composites

Mechanical failure of π‐conjugated polymer thin films is unavoidable under cyclic loading conditions, due to intrinsic defects and poor resistance to crack propagation. Here, the first tear‐resistant and room‐temperature self‐healable semiconducting composite is presented, consisting of conjugated polymers and butyl rubber elastomers. This new composite displays both a record‐low elastic modulus (<1 MPa) and ultrahigh deformability with fracture strain above 800%. More importantly, failure behavior is not sensitive to precut notches under deformation. Autonomous self‐healing at room temperature, both mechanical and electronic, is demonstrated through the physical contact of two separate films. The composite film also shows device stability in the ambient environment over 5 months due to much‐improved barrier property to both oxygen and water. Butyl rubber is broadly applicable to various p‐type and n‐type semiconducting polymers for fabricating self‐healable electronics to provide new resilient electronics that mimic the tear resistance and healable property of human skin.     

半导体碳纳米管的长度分选及其薄膜晶体管性能研究

半导体型碳纳米管薄膜的高质量制备及其优化对于碳纳米管基电子器件具有重要意义.其中半导体型碳纳米管的长度是影响薄膜质量的重要因素之一.文章通过聚[9-(1-辛酰基)-9H-咔唑-2,7-二基](PCz)成功制备了高纯度半导体型碳纳米管溶液,经过循环沉积工艺,高效地降低了分散液中的短碳管含量,有效地提升了半导体型碳纳米管的平均长度,在此基础上通过标准工艺成功制备了高性能碳纳米管薄膜晶体管.结果显示,优化后的长碳纳米管溶液制备的薄膜晶体管具有优异的电学性能,其开关比高达107,迁移率高达34 cm2·V-1·s-1,比相应的短管性能提升了 3倍.     

Application of photoelectrochemical methods for the characterization of Cu(I) oxide layers modified in the presence of corrosion inhibitors

The influence of azole-type corrosion inhibitors (benzotriazole, mercaptobenzothiazole or mercaptobenzoxazole) on the photoelectrochemical behaviour of copper electrodes under open-circuit potential was investigated in a 0.5 M NaCl solution. A correlation between the inhibition efficiency of an inhibitor, the oxide layer thickness, the polarization resistance and the semiconducting properties of the Cu₂O layer more or less stabilized by the inhibitor was proposed. It appeared that a protective oxide layer is characterized by simultaneous p and n-type conductivities, and by a decrease of the photocurrent in the cathodic range, with increasing immersion time.     

SrTiO3双功能陶瓷中CaTiO3掺杂的研究

研究了ＣａＴｉＯ３掺杂对ＳｒＴｉＯ３电容－压敏陶瓷材料微观结构和电性能的作用。ＸＲＤ和ＩＲ分析结果表明过量Ｃａ＾２＋掺杂使得晶格结构的对称性和分子规整度降低。电性能测试表明Ｃａ＾２＋掺杂利于降低烧结后的表观电阻率,压敏电压和表观介电常数随ＣａＴｉＯ３含量的增大分别表现出量小、最大值。     

Arrays of Ordered Pb Nanowires and Their Optical Properties for Laminated Polarizers

A laminated micropolarizer of Pb nanowire arrays was fabricated within an anodic alumina membrane (AAM) by anodization of the pure Al foil and subsequent electrodeposition of Pb. X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, selected‐area electron diffraction, and high‐resolution electron microscopy investigations reveal that the ordered Pb nanowires are essentially single crystal, and have an average diameter of 40 nm. Spectrophotometry measurements show that the Pb nanowire arrays embedded in AAM can only transmit polarized light vertical to the wires. An extinction ratio of 17 to 18 dB and an average insertion loss of 0.4 dB cm^–1 in the wavelength range of 1 to 2.2 μm were obtained, respectively. Therefore, these Pb nanowire/AAM composites can be used as a wire grid type micropolarizer.     

12 kV开关柜内部放电的分析与处理

分析了12kV开关柜内绝缘材料和铁板连接处发生放电的原因;提出了采用半导体堵泥封堵连接处空气间隙的方法来消除放电,通过试验和实践验证了该方法的有效性。     

不同射频溅射功率下直接制备Ca_2Si薄膜(英文)

磁控溅射系统在恒定Ar气压和Ar气流流量下,使用不同射频溅射功率在Si(100)衬底上分别沉积Ca薄膜;随后,800℃真空退火1 h.立方相的Ca2Si薄膜首次、单独、直接生长在Si(100)衬底上.实验结果指出,在多相共生的Ca-Si化合物中,沉积Ca薄膜时的射频溅射功率影响了立方相Ca2Si薄膜的质量;最优化的溅射功率是85 W.另外,退火温度为800℃时,有利于单一相Ca2Si的独立生长.并且,退火时间也是关键因素.     

Fabrication and characteristics of porous germanium films

Porous germanium films with good adhesion to the substrate were produced by annealing GeO₂ ceramic films in H₂ atmosphere. The reduction of GeO₂ started at the top of a film and resulted in a Ge layer with a highly porous surface. TEM and Raman measurements reveal small Ge crystallites at the top layer and a higher degree of crystallinity at the bottom part of the Ge film; visible photoluminescence was detected from the small crystallites. Porous Ge films exhibit high density of holes (10²⁰ cm⁻³) and a maximum of Hall mobility at ∼225 K. Their p-type conductivity is dominated by the defect scattering mechanism.