【摘要】 贵金属和二维半导体构建的异质结为等离激元纳米结构产生的热载流子提供了独特的电荷传输路径,有望应用于各种等离激元和光电子器件.然而,传统异质结构的电荷转移速度和效率通常受限于有限的界面面积和不可避免的界面污染.本文中,具有原子级清洁和较大接触界面的新型Au@MoS₂核壳异质结构能够实现超快和高效的热电子转移.飞秒瞬态吸收光谱研究表明,Au@MoS₂中从金纳米颗粒到MoS₂的热电子注入时间常数小于244 fs,而机械转移方法制备的Au/MoS₂对照样品的热电子注入时间常数为493 fs,同时,电荷转移效率从Au/MoS₂的3.33%提升至Au@MoS₂的25.3%.开尔文探针力显微镜和离散偶极近似研究进一步证明了上述结果,明显改善的电荷转移归因于原子级清洁和完全封装的异质结界面.这项研究提供了贵金属-二维半导体异质结构内固有电荷转移的基本理解,从而展现了Au@MoS₂这一新型异质结结构在等离激元和光电子器件中的应用前景.更多还原

【Abstract】 Heterostructures constructed by noble metals and two-dimensional（2D） semiconductors offer a unique charge transport path to collect hot carriers from plasmonic nanostructures and thus are promising for various plasmonic and optoelectronic devices.However,the desired charge transfer speed and efficiency of the conventional heterostructures are usually restricted by the limited interface area and inevitable interface distortion and contamination.Herein,we report the ultrafast and high-efficiency hot electron transfer by creating a novel Au@MoS₂ core-shell heterostructure with atomically sharp and dramatically enlarged interface.Our femtosecond transient absorption spectroscopy study indicates the hot-electron injection from Au nanoparticles to MoS₂ in Au@MoS₂ is within 244 fs,compared with the 493 fs of the mechanically-transferred Au/MoS₂ control sample.And meanwhile,the injection efficiency is improved from 3.33 % of Au/MoS₂ to 25.3 % of our Au@MoS₂.The results are further proved by Kelvin probe force microscopy and discrete dipolar approximation studies,which provide strong evidences that the improved charge transfer is attributed to the atomic-level clean and fully-encapsulated interface of the product.This study provides fundamental understanding of the intrinsic charge transfer within Au@MoS₂ heterostructures and thus demonstrates an intriguing material geometry for future plasmonic and optoelectronic devices.更多还原