氧化物肢体纳米晶的可控合成及其在溶液工艺发光二极管中的应用

发布时间：2018-10-19 07:18

【摘要】：胶体氧化物纳米晶具有出色的溶液加工性、独特的光电性能可调性和优异的化学稳定性,有极大潜力作为载流子传输材料应用于高性能的溶液工艺光电器件。溶液工艺光电器件的结构多样,同时所涉及的活性层材料丰富,因此为特定器件“量身定制”载流子传输层需要调控氧化物纳米晶的能带结构和光电性质。本论文从胶体氧化物纳米晶的光电性能调控出发,分别以电子传输层材料——-n型ZnO基纳米晶和空穴传输层材料———p型NiO基纳米晶作为对象,通过对反应体系的深入研究与合成路线的创新设计,实现了有机相制备掺杂／合金化氧化物纳米晶,并在此基础上通过发光二极管(light emitting diode, LED)原型器件证明可控掺杂／合金化提升了NiO基纳米晶空穴传输层的性能。理解胶体氧化物纳米晶的合成化学是对其进行性能调控和应用开发的前提,也是本论文主要研究的问题。对于ZnO基材料,我们发现醇解反应路径中金属前驱体反应活性的调控对于杂离子的引入和避免杂质分相具有决定性作用,从而结合“能带工程”概念,成功地制备出CdxZn1-xO合金纳米晶。通过制备多种尺寸的CdxZn1-xO和MgxZn1-xO以及纯ZnO纳米晶并测量其光学禁带宽度,总结出量子限域效应和合金化共同作用的ZnO基合金纳米晶禁带宽度的变化规律,实现了ZnO基纳米晶的禁带宽度在3.3～3.9 eV范围内的连续调控。对于NiO基材料,我们基于两种不同的杂原子引入方法,成功地将Co2+和Cu2+分别引入NiO的晶格中,分别将得到合金元素成分从0到100%连续变化的CoXNi1-sO氧化物合金纳米晶和单一组分的CuxNi1-xO纳米晶；从金属前驱体反应活性出发,引入“表面掺杂”的概念,解决在前驱体反应活性差异极大的情况下的掺杂／合金化难题。随后,我们以CuxNi1-xO纳米晶为例研究空穴传输材料光电特性的调控对于提升溶液工艺LED器件性能的作用。首先证明了Cu2+的引入可以有效地提升NiO纳米晶薄膜的电导率；而后选择量子点发光二极管(quantum-dot light emitting diode,QLED)为原型器件,分别利用NiO和CuxNi1-x0纳米晶作为其空穴传输层。我们发现CuxNi1-xO纳米晶的器件相比于NiO纳米晶的器件性能有显著提升：开启电压降低,功率效率提高。这一结果预示CuxNi1-xO纳米晶空穴传输层有可能在高性能QLED中扮演重要角色。本论文的研究成果将有助于发展掺杂／合金化的胶体氧化物纳米晶的合成化学,并推动氧化物纳米晶应用于溶液工艺光电器件的载流子传输层。
[Abstract]:Colloidal oxide nanocrystals have excellent solution processability, unique optoelectronic properties, tunable and excellent chemical stability, and have great potential to be used as carrier transport materials in high performance solution process optoelectronic devices. The structure of photovoltaic devices in solution process is diverse, and the active layer materials involved are rich. Therefore, it is necessary to regulate the energy band structure and optoelectronic properties of oxide nanocrystals by customizing the carrier transport layer for specific devices. In order to control the optoelectronic properties of colloidal oxide nanocrystals, the electron-transport layer materials (n type ZnO based nanocrystals) and hole transport layer materials (p type NiO based nanocrystals) are taken as objects in this thesis. Through the deep study of the reaction system and the innovative design of the synthesis route, the doped / alloyed oxide nanocrystals were prepared by organic phase. On this basis, the controllable doping / alloying has been proved to improve the performance of NiO based nanocrystalline hole transport layer by (light emitting diode, LED) prototype device. Understanding the synthetic chemistry of colloidal oxide nanocrystals is the premise of its performance regulation and application development. For ZnO based materials, we find that the regulation of the reaction activity of metal precursors in the alcoholysis reaction path plays a decisive role in the introduction of hetero-ions and the avoidance of impurity separation, thus combining the concept of "energy band engineering". Nanocrystalline CdxZn1-xO alloy was successfully prepared. By preparing various sizes of CdxZn1-xO and MgxZn1-xO and pure ZnO nanocrystals and measuring their optical band gap, the variation of band gap of ZnO based alloy with quantum limiting effect and alloying is summarized. The band gap of ZnO based nanocrystals is controlled continuously in the range of 3. 3 ~ 3. 9 eV. For NiO based materials, we successfully introduce Co2 and Cu2 into the lattice of NiO based on two different methods of introducing heteroatoms. The nanocrystalline of CoXNi1-sO oxide alloy and the CuxNi1-xO nanocrystalline of a single component were obtained, respectively. The concept of "surface doping" was introduced from the reaction activity of metal precursor. To solve the doping / alloying problem when the precursor reaction activity is very different. Then, we take the CuxNi1-xO nanocrystals as an example to study the effect of the control of the photoelectric properties of the hole-transport materials on the enhancement of the properties of the LED devices in the solution process. It is proved that the introduction of Cu2 can effectively enhance the conductivity of NiO nanocrystalline films, and then the quantum dot light-emitting diode (quantum-dot light emitting diode,QLED) is selected as the prototype device, and NiO and CuxNi1-x0 nanocrystals are used as the hole transport layer respectively. We find that the performance of CuxNi1-xO nanocrystalline devices is significantly improved compared with that of NiO nanocrystalline devices: lower switching voltage and higher power efficiency. This result indicates that CuxNi1-xO nanocrystalline hole transport layer may play an important role in high performance QLED. The research results in this paper will be helpful to develop the synthetic chemistry of doped / alloyed colloidal oxide nanocrystals and to promote the application of oxide nanocrystals in the carrier transport layer of photovoltaic devices in solution process.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN312.8;TB383.1

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