基于石墨烯透明导电薄膜的OLED研究进展

作为透明导电薄膜材料,石墨烯（Graphene）因具有十分优异的力学、光学和电学特性,在未来的柔性光电器件如触摸屏、有机发光二极管（OLED）和有机光伏电池（OPV）中表现出极大的发展潜力和广阔的应用前景。然而,受面电阻大、功函数不匹配以及表面粗糙度等关键因素的影响,基于本征石墨烯薄膜的光电器件的性能较低、稳定性较差,严重阻碍了石墨烯薄膜在柔性光电器件中的发展和应用。主要针对近年来石墨烯透明导电薄膜在OLED中应用的研究进展进行概述,并总结得出可以通过石墨烯薄膜掺杂、表面功函数修饰、清洁无损转移,以及器件结构优化等方法,进一步提高器件的性能。最后分析了石墨烯透明导电薄膜在OLED器件应用中的关键技术瓶颈,并对石墨烯透明导电薄膜在OLED中的应用前景进行了展望。     

Magnetic properties and microstructure of sputtered Co-Cr films

The magnetic properties of sputter-deposited Co-Cr films are discussed in relation to the microstructure observed using high resolution transmission electron microscopy. When the dispersion angle ΔΘ₅₀ of the c axis from the film normal decreases, a columnar structure becomes less clear. Detailed observation of a column in a poorly oriented film revealed the existence of a great number of slip bands associated with stacking faults. These faults are considered to be the cause of the decrease in the degree of the c axis orientation. Further, the column boundary was found to be sharp, implying that no significant precipitation of chromium occured thereabouts.     

Retardation of annealing embrittlement in iron-based glasses by microaddition of cerium

The effects of microadditions of cerium on the rate of annealing embrittlement, stress relief, and as-quenched magnetic domain structure in three iron-based metallic glasses have been investigated. Ribbons melt-spun from optimally doped castings of composition Fe₈₀B₁₆Si₂C₂ and Fe₈₀B₂₀ did not embrittle during annealing until the onset of crystallization, whereas Fe₇₈B₁₃Si₉ ribbons were unaffected by cerium additions. In the first two glasses optimal doping resulted in the disappearance of quenched-in stresses in the ribbons, as evidenced by an absence of maze domains, and, for the Fe₈₀B₂₀ alloy, a slight enhancement of stress relief rate for small times and temperatures. The effects of doping were qualitatively different in the Fe₇₈B₁₃Si₉ glass. We conclude that annealing embrittlement in the first two glasses is an impurity effect, and that the embrittling impurities are oxygen and/or sulfur, the dissolved concentrations of which are strongly reduced by cerium additions. That low concentrations (50–100 at. ppm) of these impurities are sufficient to cause annealing embrittlement suggests that impurity segregation may be involved in the embrittlement process.     

The influence of copper upon the atmospheric corrosion of iron

The atmospheric corrosion of pure iron and the binary alloy Fe-0.5Cu has been analyzed by a simultaneous measurement of the anodic current density of the metal dissolution and the cathodic current density of the O₂ reduction reaction during several wet/dry cycles using a magnetic and a gas volumetric technique, respectively. The results show three typical stages of the atmospheric corrosion: stage 1 (wetting of a dry surface): rapid corrosion with rust reduction as cathodic process; stage 2 (wet surface): slow corrosion with O₂ reduction as cathodic process; and stage 3 (drying out of the surface): very rapid corrosion with O₂ reduction as the cathodic process during critical wetting of the surface. The effect of copper is restricted to stage 3, where the corrosion rate is much smaller for the Fe-0.5Cu alloy than for pure iron. Two models are discussed to explain these results.     

The effect of borate buffer on ortho quinone electrochemistry

Although boric acid is known to complex with various polyalcohols, it is often used as a component of buffer mixtures. Electrochemical and spectrophotometric experiments have shown that borate buffers exhibit two types of interference with ortho quinone redox systems. Ortho quinones themselves exist in equilibrium with electroinactive complexes in borate solutions. The corresponding hydroquinones formed by reduction of the quinones complex even more strongly giving complexes which may be oxidized back to the quinone, but at a much higher potential than for the hydroquinone.     

Role of dual SiOx: H based buffer at the p/i interface on the performance of single junction microcrystalline solar cells

In p-i-n structure a-Si solar cell a buffer layer with proper characteristics plays important role in improving the p/i interface of the cell, reducing mismatch of band gaps and number of recombination centres. However for p-i-n structure microcrystalline ( µc-Si: H) cell which has much less light induced degradation than a-Si:H cell, not much work has been done on development of proper buffer layer and its application to µc-Si:H cell. In this paper we have reported the development of two intrinsic oxide based microcrystalline layer having different characteristics for use as buffer layers at the p/i interface of µc-Si:H cell. Previously SiO_x:H buffer layer has been used at the p/i interface which showed positive effects. To explore the possibility of improving the performance of p-i-n structure µc-Si:H cell further we have thought it interesting to use two buffer layers with different characteristics at the p/i interface. The two buffer layers have been characterized in detail and applied at the p/i interface of the µc-Si:H cell with positive effects on all the PV parameters mainly improves the open circuit voltage (V_oc) and enhances short circuit current (I_sc). The maximum initial efficiency obtained is 8.97% with dual buffer which is 6.7% higher than that obtained by using conventional single buffer layer at the p/i interface. Stabilized efficiency of the cell with dual buffer is found to be ~9.5% higher than that with single buffer after 600 h of light soakings.     

Crystal structures and mechanical properties of M (Mg,Sr, Ba,La)xCa1−xB6 solid solution: A first principles study

First-principles calculations are performed in this work to study the effects of M (M=Mg, Sr, Ba, La) substitution in CaB₆. Both electronic structure and mechanical properties are examined. The current results indicate that the substitution of Ca by M atoms causes the lattice constants to scale linearly with the variation of x. The shear moduli of M_xCa_1−xB₆ are found to be related to the valence d-electron Mulliken charges in the lattice. The hardnesses of M (M=Mg, Ca, Sr, Ba, La)B₆ and their solid solution are calculated by analyzing the overlap populations of the B–B bonds in the solid solution system.     

Galvanic corrosion of carbon steel coupled to antimony

Galvanic corrosion of carbon steel coupled to antimony was studied in aerated and N₂-purged electrolytes at ambient and 60 °C temperatures. Free corrosion potential of antimony and carbon steel shifts to more active values with increasing temperature and N₂ purging of the electrolyte. Under all experimental conditions, antimony remains less electronegative than carbon steels. Aeration and temperature affect potentiodynamic behaviour of both materials. As a consequence, the corrosion current for the antimony–carbon steel couple increases with increasing temperature and with aeration. There was a good agreement between the corrosion currents obtained through the Evans’ experiment and super-imposed potentiodynamic scans.