关键词： Majorana束缚态   三量子点   Andreev反射  

摘要： 正常金属/量子点/超导结构可以产生Andreev反射现象,如果在量子点上耦合Majorana束缚态(MBSs),其Andreev反射电导将发生特殊的变化,因而可用于探测MBSs.研究了MBSs对连接在正常金属和超导体之间的线型三量子点输运性质的影响,发现零费米能处的Andreev反射电导在不考虑MBSs之间的耦合时始终等于0.5G0(G0=2e2/h),不受量子点能级、量子点间耦合强度、量子点与电极之间耦合强度的影响,具有明显的鲁棒性.

关键词： 量子干涉   分子电子学   电化学调控   单分子电导测量   单分子电输运  

摘要： 量子干涉是单分子尺度电子输运中独特的尺度效应之一,有望解决分子器件在纳米尺度的高效调控问题,在单分子晶体管、高热电效率材料等领域具有重要作用,其相关的实验研究已成为近10年分子电子学研究领域的重要前沿.基于单分子电子学相关表征技术,对分子量子干涉效应进行直接的观测和外场调控,对于深入理解单分子尺度电子输运中的独特量子现象,并以此设计基于新奇物理化学效应的新型单分子器件具有重要意义.本文系统总结了近10年单分子尺度电子输运量子干涉效应的相关实验研究进展,对单分子尺度电子输运的独特量子干涉效应的理论基础进行了简要介绍,并对基于量子干涉效应的器件制备进行了展望.

关键词： 石墨烯量子点   敏感层P3HT∶PCBM   聚合物太阳能电池   表面粗糙度   UV-Vis吸收光谱  

摘要： 采用溶剂热法,以氧化石墨烯为前驱体制备了石墨烯量子点(GQDs),将不同制备条件和质量分数的GQDs掺杂到聚3-己基噻吩和[6,6]-苯基-C61-丁酸甲酯(PCBM∶P3HT)中作为敏感层制备了太阳能电池器件。实验结果表明,敏感层掺杂0.2%质量分数的GQDs时,太阳能电池光电转换效率较未掺杂器件提高了16.45%。敏感层掺杂反应时间4 h和温度220℃制备的GQDs,获得低粗糙度和高紫外可见光吸收强度的敏感层薄膜,制备的太阳能电池器件光电转换效率为1.34%,较未掺杂GQDs器件提高了12.60%。因此,GQDs适宜的制备条件和掺杂浓度可以提高太阳能电池器件的光电转换效率。

关键词： 石墨烯量子点   聚合物太阳能电池   掺杂材料  

摘要： 氮元素修饰的石墨烯量子点具有良好的水溶性和分散性,尺寸小,容易成膜,比表面积较大,导电性能优良,能促进天阳能电池的能量转换效率。本文主要研究聚合物太阳能电池中石墨烯量子点掺杂材料的优化问题,通过研究结果发现,石墨烯量子点适宜的制备条件和掺杂浓度,能显著提高太阳能电池器件的光电转换效率,值得在实践中推广应用。

关键词： Bi5O7I   N   P co-doped graphene quantum dots   Photocatalysis   Ionic liquid   Charge separation  

摘要： Nitrogen and phosphorus co-doped graphene quantum dot-modified Bi5O7 I(NPG/Bi5O7 I)nanorods were fabricated via a simple solvothermal *** morphology,structure,and optical properties of the as-prepared samples were investigated by X-ray diffraction,scanning electron microscopy,high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy(XPS),and diffused reflectance *** photocatalytic performance was estimated by degrading the broad-spectrum antibiotics tetracycline and enrofloxacin under visible light *** photodegradation activity of Bi5O7 I improved after its surface was modified with NPGs,which was attributed to an increase in the photogenerated charge transport rate and a decrease in the electron-hole pair recombination *** the electron spin resonance spectra,XPS valence band data,and free radical trapping experiment results,the main active substances involved in the photocatalytic degradation process were determined to be photogenerated holes and superoxide radicals.A possible photocatalytic degradation mechanism for NPG/Bi5O7 I nanorods was proposed.

关键词： 长波红外   量子阱   选择定则   光吸收   耦合效率  

摘要： 在长波红外探测领域中,GaAs/AlGaAs量子阱材料由于其均匀性和低成本,极具应用前景,然而,子带间跃迁选择定则的的限制导致量子阱不能吸收垂直入射光,通过引入微结构是增强光吸收的主要方法。本文在简述了量子阱原理及在长波红外波段的应用前景后,综述了近年来提高光耦合效率的一些新颖微结构,指出它们各自的优势以及存在的不足,分析了今后量子阱材料微结构的发展方向。

关键词： 隧穿磁电阻   自旋过滤   I-V曲线   自旋注入效率(SIE)  

摘要： 基于非平衡格林函数结合密度泛函理论的第一性原理量子输运方法,预言一种完全自旋极化的电子器件。该器件是由半金属TiCl3做电极,半导体RhCl3做中心区搭建的磁性隧道结。分别计算小偏压范围(0~20 mV)和大偏压范围(0~0.6 V)下的自旋极化电流曲线。发现在小偏压范围内,器件的隧穿磁电阻(tunneling magnetoresistance,TMR)高达100%,并在这一偏压范围内维持稳定;在电极极化方向平行构型(parallel configuration,PC)下的自旋注入效率也高达100%,具有很强的稳定性。在大偏压范围内,随着偏压的增加TMR逐渐减小,PC构型下的自旋注入效率一直保持100%不变。最后,通过对器件投影态密度图的分析,解释上述物理现象。

关键词： Magnons   Ferrimagnets  

摘要： We theoretically show that the coupling between magnons in an antiferromagnetically coupled ferrimagnet and microwave photons in a cavity is largely enhanced at the angular momentum compensation point (TA) when TA is distinct from the magnetization compensation point. The origin of the enhanced magnon-photon coupling at TA is identified as the antiferromagnetic spin dynamics combined with a finite magnetization. Moreover, we show that strong magnon-photon coupling can be achieved at high excitation frequency in a ferrimagnet, which is challenging to achieve for a ferromagnet due to low magnon frequency and for an antiferromagnet due to weak magnon-photon coupling. Our results will invigorate research on magnon-photon coupling by proposing ferrimagnets as a versatile platform that offers advantages of both ferromagnets and antiferromagnets.

关键词： band engineering   magnetism   quantum Hall effect   quantum transport   topological insulators  

摘要： A topological insulator (TI) is a kind of novel material hosting a topological band structure and plenty of exotic topological quantum effects. Achieving quantized electrical transport, including the quantum Hall effect (QHE) and the quantum anomalous Hall effect (QAHE), is an important aspect of realizing quantum devices based on TI materials. Intense efforts are made in this field, in which the most essential research is based on the optimization of realistic TI materials. Herein, the TI material development process is reviewed, focusing on the realization of quantized transport. Especially, for QHE, the strategies to increase the surface transport ratio and decrease the threshold magnetic field of QHE are examined. For QAHE, the evolution history of magnetic TIs is introduced, and the recently discovered magnetic TI candidates with intrinsic magnetizations are discussed in detail. Moreover, future research perspectives on these novel topological quantum effects are also evaluated.