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921.
The effects of the surface energy of polymer gate dielectrics on pentacene morphology and the electrical properties of pentacene field‐effect transistors (FETs) are reported, using surface‐energy‐controllable poly(imide‐siloxane)s as gate‐dielectric layers. The surface energy of gate dielectrics strongly influences the pentacene film morphology and growth mode, producing Stranski–Krastanov growth with large and dendritic grains at high surface energy and three‐dimensional island growth with small grains at low surface energy. In spite of the small grain size (≈ 300 nm) and decreased ordering of pentacene molecules vertical to the gate dielectric with low surface energy, the mobility of FETs with a low‐surface‐energy gate dielectric is larger by a factor of about five, compared to their high‐surface‐energy counterparts. In pentacene growth on the low‐surface‐energy gate dielectric, interconnection between grains is observed and gradual lateral growth of grains causes the vacant space between grains to be filled. Hence, the higher mobility of the FETs with low‐surface‐energy gate dielectrics can be achieved by interconnection and tight packing between pentacene grains. On the other hand, the high‐surface‐energy dielectric forms the first pentacene layer with some voids and then successive, incomplete layers over the first, which can limit the transport of charge carriers and cause lower carrier mobility, in spite of the formation of large grains (≈ 1.3 μm) in a thicker pentacene film. 相似文献
922.
目标径向运动对步进频率雷达影响的分析与仿真 总被引:1,自引:0,他引:1
步进频率雷达具有较长的相干时间,因而对目标的运动较为敏感。文中分析了目标在匀速径向运动和匀加速运动情况下,运动对步进频率雷达回波相位的影响。详细分析了速度造成的耦合时延及二次相位干扰项、加速度造成的二次、三次相位干扰项对雷达成像以及分辨率的影响,分析由此造成的图像峰值降低,回波发散,甚至图像分裂,并用MATLAB语言对其进行了仿真。仿真结果也验证了分析的正确性。 相似文献
923.
924.
重庆特殊的地理环境导致因为针尖效应带来的掉话现象比较突出。介绍针尖效应,针对针尖效应引起掉话的几种情况提出3种解决方案,并对3种方案进行优劣比较。通过实际案例分析,得出在不同的情况下要用不同的方案解决掉话问题。 相似文献
925.
926.
Jaeyoung Jang Sooji Nam Kyuhyun Im Jaehyun Hur Seung Nam Cha Jineun Kim Hyung Bin Son Hwansoo Suh Marsha A. Loth John E. Anthony Jong‐Jin Park Chan Eon Park Jong Min Kim Kinam Kim 《Advanced functional materials》2012,22(5):1005-1014
The preparation of uniform large‐area highly crystalline organic semiconductor thin films that show outstanding carrier mobilities remains a challenge in the field of organic electronics, including organic field‐effect transistors. Quantitative control over the drying speed during dip‐coating permits optimization of the organic semiconductor film formation, although the kinetics of crystallization at the air–solution–substrate contact line are still not well understood. Here, we report the facile one‐step growth of self‐aligning, highly crystalline soluble acene crystal arrays that exhibit excellent field‐effect mobilities (up to 1.5 cm V?1 s?1) via an optimized dip‐coating process. We discover that optimized acene crystals grew at a particular substrate lifting‐rate in the presence of low boiling point solvents, such as dichloromethane (b.p. of 40.0 °C) or chloroform (b.p. of 60.4 °C). Variable‐temperature dip‐coating experiments using various solvents and lift rates are performed to elucidate the crystallization behavior. This bottom‐up study of soluble acene crystal growth during dip‐coating provides conditions under which one may obtain uniform organic semiconductor crystal arrays with high crystallinity and mobilities over large substrate areas, regardless of the substrate geometry (wafer substrates or cylinder‐shaped substrates). 相似文献
927.
职业院校毕业的学生其在未来工作中的表现如何在很大程度上取决于职业院校的教学质量如何.本文所提出的一些办法可以调动学生学习的积极性和主动性,实现自主学习,在提升PLC课程教学质量的同时也保障学生良好的学习效果,希望能为今后职业院校PLC课程教学的深入发展奠定良好的基础. 相似文献
928.
Triboelectric and Piezoelectric Effects in a Combined Tribo‐Piezoelectric Nanogenerator Based on an Interfacial ZnO Nanostructure 下载免费PDF全文
In this contribution, combined triboelectric and piezoelectric generators (TPEG) with a sandwich structure of aluminum‐polydimethylsiloxane/polyvinylidene fluoride composite‐carbon (Al‐PPCF‐Carbon) are fabricated for the purpose of mechanical energy harvesting. Improved by the surface modification of PPCF with zinc oxide (ZnO) nanorods through a hydrothermal method, the TPEG generates an open‐circuit voltage (Voc) of ≈40 V, a short‐circuit current (Isc) of 0.28 μA with maximum power density of ≈70 mWm?2, and maximum conversion efficiency of 34.56%. Subsequently, in order to understand the transduction mechanism of the triboelectric and piezoelectric effects, analyses focusing on the potential composition ratio in the final output and the impact of ZnO interfacial nanostructure are carried out. The observed potential ratio between triboelectric and piezoelectric effects is 12.75:1 and the highest potential improvement by ZnO nanorods of 21.8 V is achieved by the TPEG fabricated with spacer. Finally, the relationships between the voltage, power density, conversion efficiency, and the external load resistances are also discussed. Overall, the fabricated TPEG is proved to be a simple and effective nanogenerator in mechanical energy conversion with enhanced output potential and conversion efficiency. 相似文献
929.
930.