【作者】 徐晨；

【导师】 金永东；

【作者基本信息】 中国科学技术大学 ， 分析化学， 2021， 博士

【摘要】 二维纳米粒子薄膜的出现与发展丰富了二维纳米材料的内涵;目前,包括纳米阵列结构、二维超晶格材料、二维光子晶体在内的各种以不同的纳米结构为结构单元所构建的二维纳米粒子薄膜材料已经被广泛地研究并应用于光学、电子学、催化及生物医学等领域。二维纳米粒子薄膜材料结构单元的多样性(包括不同结构组分的金属纳米粒子、无机纳米晶、有机纳米粒子及生物基纳米粒子等)及其自组装方式的多样性(如:纳米粒子表面配体诱导的直接自组装、液-液界面自组装、旋涂法、层层自组装及超声悬浮自组装等)赋予了其结构功能的多样性,也促成了其应用的广泛性。二维纳米粒子薄膜有序的结构、大量的粒子相互作用也使其在磁学、光学、电子学方面表现出了一些特殊的性质。我们课题组之前的工作已经证明具有表面等离激元特性的纳米粒子组成的二维纳米粒子超构薄膜具有超越传统量子隧穿效应的超长程电子隧穿效应,本论文主要在前期工作基础上继续开展深入研究,系统探究二维等离激元纳米薄膜材料的光电特性和传感应用。1.首先,我们在课题组之前研究工作的基础上,进一步探索了这一效应的潜在机理及应用方向。以具有长程隧穿效应的Au@SiO2核壳结构纳米粒子为基础构建的电子隧穿结表现出了负微分电阻行为,通过调整金纳米粒子核的尺寸与SiO2壳厚度,可以有效地调节器件负微分电阻曲线峰位置与峰电流,此外光激发诱导的局域表面等离激元共振效应也能进一步调控其负微分电阻行为。通过一系列的证明,我们推断,致密有序的Au@SiO2纳米粒子薄膜的长程隧穿效应与金纳米粒子核的电子缓存效应两者协同作用,共同主导了负微分电阻效应的形成。其中,Au@SiO2核壳结构纳米粒子中的金纳米粒子核不仅作为表面等离激元的激发主体,还作为电子缓存容器起着重要的作用,而SiO2纳米壳层作为可调节的隧穿势垒层有效地调控着电子的储存与释放。2.在Au@SiO2纳米粒子薄膜负微分电阻效应的探究过程中,出现的一些特殊现象如在不对称结构中电激发表面等离激元共振效应的不对称方向性电流响应、金纳米粒子的电子缓存效应,促使我们进一步深入思考隧穿结器件中的电子输运行为及利用金纳米粒子的表面等离激元共振效应构建新型电子学整流器件的可能性。因此我们构建了基于金纳米粒子膜-p型Si半导体的金属-半导体异质平面结,并发现了不同于理论上描述的金-p型半导体接触的整流行为,且器件的整流比率可以通过改变金纳米粒子的尺寸、金纳米粒子薄膜的层数或施加光照来改变。我们还探究了 Au@SiO2纳米粒子薄膜-p型Si半导体接触的整流行为;包覆了 SiO2壳层的金纳米粒子膜器件仍然表现了明显的整流行为,说明这一过程中表面等离激元共振诱导的长程隧穿效应起到了重要的作用。此外,对两种异质结器件的光响应对比测试显示Au@SiO2纳米粒子薄膜-p型Si半导体器件表现出了可与其它类似器件相媲美的光电流响应。3.我们利用液-液界面自组装成膜法,制备了 Au@SiO2纳米粒子薄膜,并对各种纳米粒子的成膜性进行了实验,其中Ru@SiO2纳米粒子经过表面功能化后表现出了良好的成膜性。之前课题组的研究工作表明电极表面SiO2纳米粒子薄膜的散射作用具有大幅增强电化学发光的特性,因此我们以Ru@SiO2纳米粒子为结构单元制备了二维纳米粒子薄膜,它不仅可以为电化学发光提供增强基底,还可以作为发光体在体系中起着主要的作用。我们所制备的Ru@SiO2纳米粒子薄膜电化学发光电极与纯ITO电极相比表现出了 600倍的电化学发光增强;与纯的SiO2纳米粒子薄膜电极相比表现出了 21倍的电化学发光增强,这一增强现象主要是由于二维SiO2纳米粒子薄膜的散射增强效应与Ru(bpy)32+在电极表面的富集作用所导致的。我们利用Ru@SiO2纳米粒子薄膜电极构建了无标记的前列腺特异性抗原(PSA)电化学发光免疫传感器,这一传感器表现出了良好的稳定性与超高的灵敏度。总之,我们围绕二维plasmonic纳米粒子薄膜的设计及其光电特性进行了一系列研究。等离激元纳米粒子薄膜的电子学器件的构建及负微分电阻效应、整流效应的探究为表面等离激元纳米电子学的发展开拓了新的思路,同时Ru@SiO2纳米粒子薄膜通过散射增强效应与发光分子富集作用表现出的大幅电化学发光增强效应也为更高性能电化学发光传感器的构建提供了新的框架。更多还原

【Abstract】 Recently,the emerging 2D nanoparticle-membranes(2D-NMs)enriched the development of 2D nanomaterials,including periodical nanoarray metamaterials,2D superlattice structures and 2D photonic crystals etc.,which have been exploited for optics,nanoelectronics,catalysis and biomedicine.By virtue of the diversity of building blocks(including metal nanoparticles,inorganic nanocrystals,organic nanoparticles and bio-nanoparticles)and the techniques of 2D self-assembly(such as surface ligand-directed self-assembly,liquid-liquid interface self-assembly,spin-coating method,acoustic force induced levitation self-assembly,etc.),2D-NMs possess varieties of properties and have been applied widely in diverse fields.Meanwhile,the close-packed structure and intensive coupling of nanoparticles endow the 2D-NMs some special optical,electronic,or magnetic properties.Importantly,the previous works reported by our group have found an unprecedented long-range electron tunneling regime across Au nanoparticles with insulating SiO2-shells,up to even 25 nm.On the basis of previous findings in our group,this doctoral thesis focuses on in-depth research and systematically to explore the photoelectric characteristics and sensing applications of the two-dimensional plasmonic nanomaterials.1.Firstly,based on previous work of our group,we further explored underlying mechanism of electron transport and new applications of 2D-NMs.The planar tunneling junction based on Au@SiO2 NMs with plasmonic induced long-range electron tunneling effect showed interesting negative differential resistance(NDR)phenomenon.The NDR behavior can be tuned flexibly by changing the size of Au core and the thickness of SiO2 shell,while the illumination can further regulate the NDR behavior by localized surface plasmonic resonance effect.In addition,we have proved that the synergistic effect of plasmon assisted long-range electron tunneling(P-tunneling)and electronic caching effect of Au@SiO2 nanoparticles manages the NDR behavior,in which the Au cores are responsible for plasmonic effect and electronic caches and SiO2 shells acts as a tunable tunneling barrier.2.To further uncertain some peculiar effects as shown by the above NDR phenomenon of the Au@SiO2 NMs device,such as the directionality of excitation of plasmonic effect in junctions and the amazing electronic caching effect of Au nanoparticles,we thought deeply about the possibility for combining P-tunneling and localized surface plasmonic resonance effect to construct rectifying device.We constructed a plasmoelectric heterojunction with the direct contact between AuNP NMs and p-Si which displayed rectifying behavior.The rectifying behavior is unexpected since there is an ohmic contact of heterojunction between bulk Au and p-Si.The rectifying ratio could be varied by changing the size of Au cores,layers of NMs or illumination to tune plasmonic effect.The heterojunction between shell-isolated Au@SiO2 NMs and p-Si was further constructed to study the rectifying behavior.It is unsuprising that the heterojunction still show a rectifying behavior due to the p-tunneling effect.Moreover,the heterojunction based on shell-isolated Au@SiO2 NMs also showed impressive photoresponse comparable to the reported values of similar devices prepared from other 2D materials.3.We prepared closed-packed Ru@SiO2 NMs,and based on our previous report on SiO2 NMs possess special dramatic light scattering effect which benefits for electrochemiluminescence(ECL)enhancement,we constructed Ru@SiO2 NMs ECL electrode which displayed～600-fold enhancement of ECL intensity compared with the bare ITO electrode,due to light scattering of SiO2 NPs and the enrichment of Ru(bpy)32+molecules,and～21-fold enhancement compared with the pure SiO2 NP due to the enrichment of Ru(bpy)32+molecules at the electrode surface.The further constructed Ru@SiO2 NMs ECL immunosensor for label-free detection of prostate-specific antigen(PSA)exhibited good stability and ultrasensitive detectability.The finely designed studies and the observed NDR phenomenon and rectifying behavior of plasmonic 2D-NMs will open a new way for the development of nanoelectronics;while the Ru@SiO2 NMs with dramatical ECL enhancement will provide a new framework for the construction of higher performance ECL biosensors.更多还原