CdSe二维纳米结构薄膜液相制备及其光电特性调控研究

In this proposal, we suggest using CdSe two-dimensional (2D) colloidal nanoplatelets (NPLs) as building blocks to fabricate thin films and then to explore their controllable optical- and electrical- properties, as well as their device applications. We aim at giving a clear description of the coupled relationships among the energy-band structures, transport processes, and opto-electronic properties of the CdSe 2D NPLs thin films. To achieve it, the controllable synthesis process of the 2D NPLs and their core/shell structures will be studied first to provide building blocks for the films and also to meet the their demands for energy band.Secondly, effective ligand-exchange procedures are needed to remove the organic ligands capping on the as-synthesized NPLs for enhancing the electronic couplings between the NPLs. This step is essential for the fabrication of 2D NPLs conductive thin films because the mobility of the thin film is highly related to the electronic couplings between the NPLs in the film. Thirdly, various of optical- and electrical- measurements will be carried out to collect as much data as possible. These experimental data and the results of structure analysis, in combination with the transportation theory, photon transition and recombination model will be used to investigate the photoluminescence behavior, the generation, transportation, and recombination of photogenerated carriers. The forth part of the work, which is the most important one, is to further explore the role of the energy band in the opto-electronic properties and transport behavior by using the technique of ion implantation and electronic impurity doping, together with the different choice for 2D NPLs and those core/shell structure to change the energy band of the 2D NPLs thin films. The focus of this procedure is to clarify the influence of the ligand-exchange, electronic impurity doping, ions implantation, and energy band structure of the 2D nanoplatelets on the mobility, the energyband of the films, the photon excitation and transportation processed. Based on these information obtained above, we will further discuss the application of the 2D coupled NPLs systems on the light-emitting diode and solar cell.

胶体纳米光电子学研究是目前材料物理研究前沿。本课题提出在实现尺寸可控CdSe二维纳米结构及其核壳体系基础上，通过配体交换实现导电薄膜制备，掺杂和离子注入手段来调控纳米结构薄膜能带结构，并对其光电特性、输运过程、外场调控和器件应用加以研究。主要通过制备参数来调控二维微结构尺寸和能带结构变化、薄膜有序度及均匀性，利用配体置换来提高微结构间电子耦合和薄膜迁移率。采用掺杂和离子注入手段，结合微结构和核壳结构尺寸变化来进一步调控体系中能带结构，并通过结构分析、光电实验和输运理论相结合的方法，系统地研究二维纳米结构耦合体系中微观能带结构变化、载流子输运过程和光电响应间相互联系的物理图象及规律。集中研究配体置换、杂质掺杂、离子注入和晶粒尺寸对迁移率的影响、微观能带结构及光激发和光生载流子输运过程的调控，并在此基础上研究二维纳米结构耦合体系在发光二极管和太阳电池上的应用，推动胶体纳米光电子学的进一步发展。

胶体纳米光电子学研究是目前材料物理研究前沿。本项目针对此方面研究中的二维胶体纳米粒子的光电特性进行了创新基础研究。研究主要从一下几个方面进行：1. 盘状石墨烯量子点的合成及光学特性；2. 不同制备条件下石墨烯量子盘的发光机理及其在太阳电池上的应用；3. 壳层变化对CdSe基纳米片的界面及非线性光学性质的影响；4. 薄膜表面微结构的简易制备及对荧光量子产率的影响；5. 纳米晶薄膜的制备及其在不同光照下的电响应。通过以上研究，我们实现利用制备参数调控高纯石墨烯量子盘和掺氮石墨烯量子盘的内部结构，通过结构分析，光学实验和理论相结合的方式，系统的解释了其发光机理，并在此基础上，将掺氮石墨烯量子点应用于太阳电池上，提高太阳电池在短波波段的外量子效率；与此同时，通过改变壳层厚度，研究晶格应力对CdSe/CdS核壳纳米片界面的影响及CdSe基纳米片的非线性光学特性，指出纳米片的有效双光子吸收截面比量子点大几个数量级；最重要的是，我们发现一种提高荧光量子点聚合物薄膜量子产率的通用简易技术，即通过模板法在荧光量子点聚合物薄膜表面刻画倒金字塔微结构，可以最大化薄膜的光输出，并显著提高薄膜荧光量子产率。总的来说，研究基本达到目的。