金属纳米二聚体结构的局域表面等离子体激元共振特性研究

将金属纳米粒子二聚体结构作为光学谐振腔,采用 时域有限差分(FDTD)法仿真模拟了一种新型局域表面等离子体激光器(SPASER)。 使用洛伦兹复介电常数模型研究二聚体的增益介质特性,探讨了二聚体结构中 两个纳米局域表面等离子体激元共振(LSPR)以及相互作用机制,进一步研究了 LSPR相互作用对SPASER的局域场增强的影响。 模拟结果表明,相比较单纳米颗粒SPASER,LSPR的相互作用使得二聚体SPASER的局域电场显著 增强,增强因子最 大可以相差27倍。本文研究为纳米光学器件尤其是激光器件的设计提 供了依据。LSPR效应的 研究可以用于探索一些光与物质相互作用的极限效 应,从而为有源光子线路、生物传感以及量子信息处理等研究开辟道路。     

Ag纳米粒子等离子体共振增强太阳能电池吸收

针对薄膜太阳能电池硅薄膜层吸收效率较低的问题,提出了运用金属纳米粒子局域表面等离子体共振(LSPR)增强太阳能电池的吸收效率,采用时域有限差分(FDTD)法,模拟计算了太阳能电池中不同厚度的硅薄膜层吸收特性,分析了不同几何参数的矩形Ag纳米粒子与Ag背反射膜对增强太阳能电池吸收效率的影响作用。计算结果表明,硅薄膜层厚度为500nm的太阳能电池具有较高的吸收效率,通过调整Ag纳米粒子的相关参数,有效地降低了太阳电池硅薄膜表面的反射损耗,取得最大吸收增强因子为1.35。Ag背反射膜有效地降低了Ag纳米粒子硅薄膜结构的透射损耗,其最大的吸收增强因子达到1.42。     

纳米结构分子吸附引起的表面增强拉曼散射研究

利用模板印刷技术,制备了具有不同局域表面等离子体共振(LSPR)峰的Au纳米空心半球壳结构,并以4-巯基苯胺(4-ATP)为探针分子研究了纳米结构表面吸附分子对表面增强拉曼散射(SERS)强度的影响。结果表明,当纳米结构的LSPR峰位处于激发光波长的短波长或"马鞍型"位置时,SERS强度随吸附分子数的增加而增大;当处于长波长位置时,SERS强度呈现先增大后减小的趋势。利用分子吸附理论和纳米结构表面局域场强度变化,对此现象进行了解释。     

表面等离子体增强硅电池光吸收的研究进展

局域表面等离子体共振(LSPR)是光照射金属纳米粒子而引起金属内的自由电子发生集体共振使粒子周围的近场增强。将LSPR应用于太阳能电池,会使陷光效率大大增加,而同时降低表面复合损耗和电池基底的厚度要求。文章从粒子的大小、形状、阵列模式的周期及粒子周围的介电环境对太阳能电池的陷光的影响,介绍了基于LSPR性质的表面等离子体硅太阳能电池的陷光机理及其影响因素,对相应的研究做了系统的综述。     

局域耦合效应在GaInP太阳电池中的应用

近年来,局域耦合效应在光电转换器件中的应用受到广泛关注,在发光二极管以及硅基太阳电池中的基础与应用研究成为本领域的研究热点。然而局域耦合效应在宽禁带材料体系太阳电池中的应用仍未见系统报道。研究中利用溅射与热退火的手段在GaInP太阳电池表面成功制备了粒径与占空比可控的Au/半导体纳米异质结构,并对其退火前后的形貌进行了系统分析,后续对纳米异质结构的光学吸收现象及局域耦合效应的内在机制进行了探讨。最终,通过反射光谱的表征,在Au溅射时间为20 s和30 s样品中分别得到了2.2%和5.5%的光吸收增强。该研究提出的局域耦合效应在GaInP太阳电池中的应用,为改善GaInP太阳电池的表面吸收效率提供了一种新的思路。     

金纳米颗粒增强富硅氮化硅发光特性的研究

采用时域有限差分(FDTD)方法,对Au纳米颗粒的尺寸和形貌对于其光学特性的影响进行了系统的理论研究。通过采用等离子体增强化学气相沉积(PECVD)、晶化处理、电子束蒸发和高温退火等工艺,制备基于局域表面等离子共振(LSPR)效应的富硅氮化硅发光芯片。利用拉曼光谱仪、扫描电子显微镜(SEM)、奥林巴斯显微镜等对不同结构Au纳米颗粒富硅氮化硅发光器件的特性进行了表征。研究表明,通过对Au纳米颗粒的大小、形状和分布合理优化,富硅氮化硅芯片的发光强度在570nm波长附近提升了7倍,增强峰的位置红移了10nm。     

表面等离子体受激辐射放大领结型纳米天线的SERS单分子探测(英文)

基于表面等离激子受激辐射放大原理,提出了一种应用于表面增强拉曼散射(SERS)单分子探测的领结型纳米天线结构。采用有限元方法(FEM)研究其局域表面等离子体共振(LSPR)和SERS特性。结果表明,该领结型纳米天线的局域表面等离子体共振强度和局域电场强度得到明显的增强,其散射截面为非表面等离激子受激辐射放大领结型纳米天线的1.1×104倍,局域电场强度为1×102倍。同时,该领结型纳米天线的表面增强拉曼散射增强因子最大达到1016,足以进行精确的单分子探测;整个纳米天线表面的增强因子也可达到1012,足以应用于单个生物分子的探测。     

金属表面等离激元增强聚合物太阳电池

研究了Au纳米颗粒表面等离激元增强聚噻吩(P3HT)与富勒烯衍生物(PCBM)共混体系聚合物太阳电池的光电转换效率。Au纳米颗粒表面由双十烷基二甲基溴化铵(DDAB)修饰,能够均匀分散在活性层中。研究了Au纳米颗粒的质量分数对电池性能的影响,发现质量分数为1.2%时,电池性能最佳,转换效率高达3.76%,较未掺杂的参比电池相对提高约20%。掺入Au纳米颗粒后P3HT和PCBM共混膜光吸收显著增强,从而使电池外量子效率大大增加。电池效率的提升主要归结于Au纳米颗粒表面等离激元激发所引起的近场增强。     

PERC结构多晶硅太阳电池的研究

高效、低成本是目前硅太阳电池追求的主要目标。多晶硅太阳电池成本低,但其电性能较差。背面钝化及局部背接触是提高多晶硅太阳电池电性能的主要技术。通过采用SiO2/SiNx叠层膜作为背钝化介质层,依次经过背面开槽、丝网印刷、烧结形成背面局部接触,制备钝化发射极和背表面电池(PERC)结构多晶硅太阳电池。采用恒光源I-V特性测试系统测试其电性能,结果表明:较之常规铝背场多晶硅太阳电池,PERC结构电池在开路电压Voc、短路电流密度Jsc、转换效率η方面分别提高了13 mV、1.8 mA/cm2和0.67%(绝对值),其转换效率达到17.27%。PERC结构多晶硅电池采用了常规丝网印刷工艺,有利于实现高效多晶硅电池的产业化生产,具有很高的实际意义。     

不同金颗粒尺寸的Au@SiO_2纳米粒子拉曼增强研究

制备壳厚为2~3 nm,核尺寸为15、25、50 nm的Au@Si O_2纳米粒子代替Au纳米粒子,用来研究电磁场耦合强度与粒子尺寸和间距之间的关系。实验结果表明处在硅衬底上核尺寸为50 nm的Au@Si O_2纳米粒子增强效果更佳。为了进一步提高Au@Si O_2纳米粒子的拉曼活性,将核尺寸为50 nm的Au@Si O_2纳米粒子置于光滑的金表面,结果表明罗丹明6G的信号获得了更大的增强。利用时域有限差分法分别计算了不同粒径、间距和处在不同基底材料上的Au纳米粒子二聚体的表面增强拉曼散射(SERS)活性,结果表明粒子尺寸越大,间距越小,处在金衬底上的Au纳米粒子二聚体电磁场耦合强度越高,这与实验结果完全相符。另外,粒子间的耦合方式从粒子间隙转移到粒子与衬底之间,克服了粒子间距不可控的问题。这为获得灵敏度和稳定性更高的拉曼活性基底提供了新的思路。     

Localized Surface Plasmon Resonance Enhanced Photocatalytic Hydrogen Evolution via Pt@Au NRs/C3N4 Nanotubes under Visible‐Light Irradiation

Au nanorods (NRs) decorated carbon nitride nanotubes (Au NRs/CNNTs) photocatalysts have been designed and prepared by impregnation–annealing approach. Localized surface plasmon resonance (LSPR) peaks of Au NRs can be adjusted by changing the aspect ratios, and the light absorption range of Au NRs/CNNTs is extended to longer wavelength even near‐infrared light. Optimal composition of Pt@Au NR₇₆₉/CNNT₆₅₀ has been achieved by adjusting the LSPR peaks of Au NRs and further depositing Pt nanoparticles (NPs), and the photocatalytic H₂ evolution rate is 207.0 µmol h^?1 (20 mg catalyst). Preliminary LSPR enhancement photocatalytic mechanism is suggested. On one hand, LSPR of Au NRs is beneficial for visible‐light utilization. On the other hand, Pt NPs and Au NRs have a synergetic enhancement effect on photocatalytic H₂ evolution of CNNTs, in which the local electromagnetic field can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally Pt as co‐catalyst can boost H⁺ reduction rate. This work provides a new way to develop efficient photocatalysts for splitting water, which can simultaneously extend light absorption range and facilitate carrier generation, transportation and reduce carrier recombination.     

Au/TiO2复合纳米结构增强热电子光电探测器宽谱响应性能

宽谱响应光电探测器在图像传感和光通信等领域应用前景广阔。金属微纳结构通过激发表面等离激元共振效应可高效产生热载流子,将它们与宽带隙半导体构成异质结构,便可利用热载流子开发出低成本宽谱响应光电探测器。研究设计了一种基于Au/TiO₂复合纳米结构的热电子光电探测器。其中TiO₂层经退火后形成尺度约为百纳米的凹凸结构,Au纳米颗粒层与用作电极的保形Au膜共同组成了激发表面等离激元共振的纳米结构。由于Au/TiO₂复合纳米结构的协同作用,该器件在400～900 nm范围内具有宽谱光吸收性能,器件的平均光吸收效率为33.84%。在此基础上,该器件能够探测TiO₂本征吸收波段以外的入射光子。例如,在600 nm波长处,器件的响应率为9.67μA/W,线性动态范围为60 dB,器件的上升/下降响应速度分别为1.6 ms和1.5 ms。此外,利用有限元法进行了仿真计算,通过电场分布图验证了Au/TiO₂复合纳米结构中所激发的丰富表面等离激元共振效应是其实现宽谱高效探测的原因所在。     

Enhancement of the power conversion efficiency due to the plasmonic resonant effect of Au nanoparticles in ZnO nanoripples

Au-ZnO nanoripples (NRs) were synthesized by using a sol-gel method for utilization as an electron transport layer (ETL) in inverted organic photovoltaic (OPV) cells. Absorption spectra showed that the plasmonic broadband light absorption of the ZnO NRs was increased due to the embedded Au nanoparticles (NPs). In particular, as compared to regular inverted OPV cells with a ZnO NR ETL, the incident photon-to-current efficiency of the inverted OPV cells with a Au-ZnO NR ETL was significantly enhanced due to the localized surface plasmon resonance (LSPR) effect of the Au NRs. The enhancement of the short-circuit current density (10.05 mA/cm²) of the inverted OPV cells with a Au-ZnO NR ETL was achieved by the insertion of the Au NPs into the ZnO NRs. The power conversion efficiency (PCE) of the OPV cells with Au-ZnO NRs was 3.25%. The PCE of the inverted OPV cells fabricated with a Au-ZnO NR ETL was significantly improved by 20.37% in comparison with that of inverted OPV cells fabricated with a ZnO NR ETL. This improvement can mainly be attributed to an increase in light absorption in the active layer due to the generation of the LSPR effect resulting from the existence of the Au NPs embedded in the ZnO NRs.     

Localized Surface Plasmon Resonance Promotes Metal–Organic Framework-Based Photocatalytic Hydrogen Evolution

Combining metal nanoparticles (NPs) featured with localized surface plasmon resonance (LSPR) with metal–organic framework (MOF)-based photocatalysts is a novel means for achieving efficient separation of electron–hole pairs. Herein, the Au@NH₂-UiO-66/CdS composites are successfully synthesized by encapsulating Au NPs with LSPR into the NH₂-UiO-66 nanocage, further growing CdS NPs on the surface of the NH₂-UiO-66, which exhibits higher photocatalytic activity in hydrogen evolution reaction under visible-light irradiation than that of NH₂-UiO-66/CdS and CdS, respectively. Transient absorption measurements reveal that MOF is not only a transit station for electrons generated from CdS to Au, but also a receiver for hot electrons generated from plasmonic Au in Au@MOF/CdS composites. Thus, the LSPR-induced hot electron transfer from Au NPs is an important manifestation to prolong the carrier lifetime and enhance the photocatalytic performance. This work provides insights into investigating the photoinduced carrier dynamics of nanomaterials with LSPR effects for enhancing the MOF-based photocatalytic performance.     

Enhancement of the current efficiency of organic light-emitting devices due to the surface plasmonic resonance effect of dodecanethilol-functionalized Au nanoparticles

The photoluminescence intensity of the dodecanethilol-functionalized Au (DDT-Au) nanoparticle (NP) layer/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC)/4,4′-bis(N-carbazolyl)-1,1′-biphenyl:tris(2-phenylpyridine)iridium (III) (CPB:Ir(ppy)₃) film was increased by about 1.15 times compared to that of the TAPC/CPB:Ir(ppy)₃ film due to the effect of coupling between the excitons in the emitting layer and a localized surface plasmonic resonance (LSPR) in the DDT-Au NPs. The current efficiency of the organic light-emitting devices (OLEDs) with the DDT-Au NP layer at 100 cd/m² was 14.9 cd/A larger than that without the DDT-Au NP layer, resulting in an enhancement of the out-coupling efficiency. The increase in the current efficiency of the OLEDs with a DDT-Au NP layer was attributed to the enhanced out-coupling efficiency due to the existence of the LSPR generated by the DDT-Au NPs.     

Incorporation of silver and gold nanostructures for performance improvement in P3HT: PCBM inverted solar cell with rGO/ZnO nanocomposite as an electron transport layer

Inefficient light absorption and inefficient charge separation are considered as two major impediments for the efficiency improvement in bulk heterojunction organic solar cells (BHJ OSCs). In this work, we report the simultaneous role of modified electron transport layer (ETL) and photoactive layers on the performance of poly (3-hexylthiophene), [6, 6]-phenyl C61-butyric acid methyl ester (P3HT: PCBM) BHJ OSCs. To modify the ETL, composite of reduced graphene oxide (rGO) (0.4 wt %) and ZnO nanoparticles (NPs) was used, which resulted in efficiency enhancement from 3.13 to 3.81%, as compared to a value of 3.13% when only ZnO was used. Thereafter, to improve upon the optical absorption properties, the photoactive layer is modified by embedding nanoparticles and nanorods of Ag and Au into it. The size of Ag and Au nanoparticles were chosen to be 50 nm while the dimensions of Ag and Au nanorods were so controlled to obtain length of approx. 50 nm and width of ∼10 nm. All the devices were fabricated in inverted geometry and 20 wt% nanostructures embedded devices showed the best results. For Ag and Au NPs embedded devices, the maximum power conversion efficiency was found to be 4.21% and 4.44%, respectively. On the other hand, for Ag and Au NRs embedded devices, the maximum efficiency was 4.37% and 4.85%, respectively. For comparison, the control devices where no nanostructures were embedded, which shows efficiency of 3.81%. Therefore, an overall enhancement in efficiency was nearly 1.21 and 1.1, 1.16, 1.14, 1.27 fold after modifying ETL as well as the active layer. The reasons for performance improvement were ascribed to better charge extraction properties of ETL, enhanced light absorption due to localized surface plasmon resonance (LSPR) and efficient light scattering by the nanostructures and improved global mobilities.     

(100)取向AlN薄膜的制备及其压电性能研究

采用射频磁控溅射法,在Si(100)衬底(含Au导电层)上制备了(100)取向的AlN薄膜并研究了工作压强和溅射功率对制备的AlN薄膜性能的影响。利用X射线衍射仪(XRD)分析了薄膜结构特性,结果表明,在一定范围内,工作压强的增加和溅射功率的减小更有利于AlN(100)晶面择优取向的生长。利用压电力显微镜(PFM)对AlN薄膜的形貌和压电性能进行了表征,发现(100)择优取向的AlN薄膜的压电性主要表现在薄膜面内方向上。     

溅射功率对Au与CdZnTe晶体接触结构和性能的影响

采用直流磁控溅射工艺,以Au为靶材在高阻半导体CdZnTe上制备导电薄膜.系统地研究了溅射功率对沉积速率、薄膜结构、组织形貌及接触性能的影响.结果表明,随溅射功率的增加沉积速率增大.I-V测试表明在高阻CdZnTe上溅射Au薄膜后不经热处理已具有良好的欧姆接触性能,溅射功率为100 W时的接触性能好于功率为40 W和70 W时的接触性能.     

Ultra-Small ATP-Decorated Gold Nanoparticles for Targeting Amyloid Fibrils in Neurodegenerative Diseases

Ultrafine Gold nanoparticles (Au NPs) functionalized with various biomolecules constitute an alternative to antibodies as anti-amyloidogenic agents. However, generating stable ultrafine Au NPs with high surface activity is challenging. Here, the capacity of phosphate groups in biomolecules is used to stabilize Au NPs. The characteristics of Au NPs decorated with adenosine mono-, di-, and tri-phosphate are compared as well as adenosine and peptide nucleic acid-containing adenosine as controls. Among them, ATP-Au NPs are found to be superior having small size (2–4 nm) and stability (for several months) when analysed by spectroscopy and electron microscopy. Spectroscopy analysis also revealed that each ATP-stabilized Au NP is decorated with 7–8 molecules of ATP. ThT binding analysis and TEM imaging showed that the ATP-Au NPs efficiently prevented amyloid fibril formation in vitro by Aβ-42, α-Synuclein as well as by the Glucosylceramide metabolite, and disaggregated their pre-formed fibrils. NMR analysis revealed the interaction of the ATP-Au NPs with the amyloid fibrils. The ATP-Au NPs are safe toward cultured SH-SY5Y cells and when co-incubated with α-Synuclein amyloids inhibited their cytotoxicity and readily enter the cells to inhibit formation of amyloid fibrils within them. The results indicates the pharmacological potentials of ATP decorated Au NPs.     

玻璃衬底上RF磁控溅射CIGS薄膜的研究

采用射频磁控溅射的工艺,在玻璃衬底上制备得到了铜铟镓硒(CIGS)薄膜。讨论了衬底温度、溅射气压、退火与否对CIGS薄膜与衬底结合力、显微形貌、晶化程度及电阻率的影响。通过能谱(EDS)测试证明了溅射的CIGS薄膜Ga组分比符合高效吸收层的要求,通过X射线衍射(XRD)与扫描电子显微镜(SEM)测试,证明了衬底加热溅射、溅射后450℃空气退火可以有效提高CIGS薄膜与衬底的结合并提高晶化程度。通过四探针法电阻率测试证明了低气压条件下溅射、溅射后退火可以有效降低CIGS的电阻率,通过透射光谱分析证明了CIGS薄膜对可见光有高吸收效率,适合作为太阳电池的高效吸收层。