半导体纳米阵列表界面设计及其在太阳能转换中的应用研究

发布时间：2018-05-02 01:31

本文选题：纳米阵列材料 + 能源　；参考：《中国科学技术大学》2017年博士论文

【摘要】：现今能源和环境问题尤为突出,寻找清洁可持续的替代能源以及高效无污染的能源转换方式成为了当前科学研究的重要课题。太阳能作为清洁、丰富且广泛的能源可通过太阳能-电能和太阳能-化学能等多种转化形式得到有效利用。近年来纳米材料的发展和研究给太阳能转换以新的生机。由于其潜在的理论和实际应用价值,纳米材料在太阳能转换方面扮演着越来越重要的角色。其中,纳米阵列材料在电子传输、光学吸收等方面具有突出的优势,为发展高效利用和转换太阳能带来了新的契机。表界面的设计对于催化性能、载流子传输等方面的优化作用开始受到重视。但是一些作用机制不明以及应用研究的不足制约着纳米阵列材料的发展。本论文基于“自上而下”和“自下而上”的制造合成方法制备无机纳米阵列结构,并通过表界面的表面悬键、助催化剂、等离激元的设计调控表界面状态以研究表界面调控对于光驱动催化反应过程的影响,以及等离激元效应在光电器件的作用。本论文中,我们根据太阳能转换中的性能表现和表界面之间的构效关系来进一步研究作用的机理,具体的是通过调控表面悬键状态来研究表面悬键在光催化中的作用机制;通过调控纳米阵列表面助催化剂以调控表面电子状态,并研究其对光驱动催化反应的影响;通过调控化学反应环境以研究其对光电催化氧化反应的影响;在光伏器件中引入等离激元效应,研究热电子在光伏器件中的作用机制。所取得的主要研究成果如下:1.发展了选择性调控硅纳米线表面悬键类型和数量的方法,在纯水体系中研究了不同表面悬键在光催化水分解中的作用以及相关机制。表面修饰Si-H键的硅纳米线的光催化水分解产生氢氧比高于2,通过光电测试及红外光谱等验证了光生载流子的分离、寿命与表面悬键的关系,以及推测出表面悬键Si-H键、Si-OH键在光催化中的相关作用。通过模拟光催化的反应路径,我们推测出Si-H表面发生光催化的反应为:Si(h+) + Si-H(e-)+ H2O → Si-OH + Si + H2。通过实验手段可以理性地调变硅纳米线的表面悬键状态以调控其光催化制氢性能,为开发高效硅基光催化剂提供了新的表面工程思路。2.以硅纳米线及表面修饰贵金属Pd和Pt共催化剂为体系,利用硅纳米线表面悬键进行原位光驱动有机催化加氢反应,通过钯和铂的构建以调控硅纳米线表面电子状态,研究表面电子状态对于光驱动有机加氢、有机氧化反应等反应转换率及选择性的影响。另外以介孔硅纳米线为研究体系,研究介孔硅纳米线活化氧分子的特性对于光驱动有机氧化反应的影响。为利用硅纳米结构表界面设计用于光驱动有机反应的研究奠定了基础。3.以BiVO4纳米介孔阵列结构、具有等离激元的Ag纳米片和析氧反应催化剂Co(OH)2为体系,利用BiVO4进行光电催化丙三醇的选择性氧化转换,研究了溶液pH值和偏压对光电催化有机反应的选择性的影响,结果证明在酸性条件下(pH=2)二羟基丙酮和高值产物的产率和选择性、法拉第效率都是最高的,可以得到二轻基丙酮选择性达50%,产率达55.92mmol/g/h的催化效果(1.2Vvs RHE, H型电解槽)。H+的浓度影响了反应路径、产物的选择性,外加偏压可以更好的增加载流子分离能力、增大电流密度,并不影响反应路径选择。另外,研究了在中性反应液中贵金属纳米结构的等离激元效应以及Co(OH)2材料对其催化性能的影响。为实现太阳能高效选择性催化氧化反应生产高值化工制品奠定了研究基础。4.以N型硅纳米线-PEDOT:PSS (聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸))无机有机异质结型光伏器件和N型硅纳米线-rGO (还原氧化石墨烯)肖特基型光伏器件为体系,研究了在近红外区域具有等离激元的金属Ag纳米片增强近红外区域的光伏器件光电转换效率的作用机制,并设计了以此机制构建的柔性光伏器件。金属Ag纳米片在近红外区域激发等离激元,产生热电子,发现当银纳米片直接接触N型硅纳米线时,即热电子直接注入到硅的导带中时,可以使得光伏转换效率额大幅提高,尤其是在近红外区域有着明显提升,以800nm处为例,提高了 59 %。通过分别构建N型和P型硅纳米线基光伏器件,分析了等离激元热电子增强效应在光伏器件中的作用机制。基于这一机制,我们通过微纳加工手段制备了柔性的近红外效率增强的光伏器件。为实现广谱光吸收的光伏器件的界面设计提供精准制造基础,为高效光电转换构建了新的界面工程思路。
[Abstract]:Nowadays, energy and environmental problems are particularly prominent. Looking for clean and sustainable alternative energy and efficient and non polluting energy conversion have become an important subject in the current scientific research. As a clean, rich and extensive energy, solar energy can be effectively used in various forms of conversion by solar energy and solar energy chemical energy. The development and research of nanomaterials have brought new vitality to solar energy conversion in the past year. Due to its potential theoretical and practical application, nanomaterials play a more and more important role in the conversion of solar energy. Solar energy exchange has brought new opportunities. The design of the surface interface has been paid more attention to the optimization of catalytic performance, carrier transmission and so on. However, some mechanism of action is unclear and the lack of application research restricts the development of nanoarray materials. This paper is based on "top-down" and "bottom-up" manufacturing synthesis method. The structure of inorganic nanoscale arrays was prepared, and the surface state of the surface suspension, cocatalyst, and plasmons was designed and regulated to study the influence of the surface interface regulation on the light driven catalytic reaction process and the effect of the plasmon effect on the optoelectronic devices. In this paper, we based on the performance of the solar energy conversion and the performance of the solar energy conversion. The mechanism of the interaction between the surface interfaces is further studied. The mechanism of the action of the surface suspension bond in the photocatalysis is studied by regulating the state of the surface suspension bond. The surface electron state is regulated by regulating the surface cocatalyst of the nano array, and the effect on the dynamic catalytic reaction of the optical drive is studied. The chemical reaction is regulated by the control of the chemical reaction. The environment is used to study its effect on the photoelectrochemical oxidation reaction; the effect mechanism of thermal electrons in the photovoltaic devices is studied in the photovoltaic devices. The main achievements are as follows: 1. the methods to selectively regulate the type and quantity of the surface suspension bonds of silicon nanowires are developed, and the different surfaces are studied in the pure water system. The role of the suspension bond in the photocatalytic water decomposition and the related mechanism. The photocatalytic water decomposition of the silicon nanowires with the surface modified Si-H bond produces more than 2 hydrogen and oxygen ratio. The separation of light carriers, the relationship between the lifetime and the surface suspension bond, the surface suspended bond Si-H bond, and the Si-OH bond in the photocatalysis are verified by the photodecomposition of the photocatalytic water decomposition of the silicon nanowire surface modified by the surface modification. By simulating the reaction path of photocatalytic catalysis, we speculate that the photocatalytic reaction of Si-H surface is: Si (h+) + Si-H (e-) + H2O, Si-OH + Si + H2. can regulate the surface suspension state of silicon nanowires rationally in order to regulate the performance of photocatalytic hydrogen production by means of experimental means and provide a new method for the development of high efficiency silicon based photocatalyst. The surface engineering idea.2. is based on the silicon nanowires and the surface modified noble metal Pd and Pt Co catalysts, using the silicon nanowire surface suspension to carry on the in-situ light driven organic catalytic hydrogenation. The surface electron state of the silicon nanowire is regulated by the construction of palladium and platinum to study the surface electric substate for the organic hydrogenation and the organic oxidation. In addition, the influence of the conversion rate and selectivity of the mesoporous silicon nanowires was also studied. The effects of the properties of the mesoporous silicon nanowires on the light driven organic oxidation were studied. The basis for the study of the optical driven organic reaction using the silicon nanostructure surface interface was laid on the basis of the.3. nano mesoporous array junction. The Ag nanoscale and the oxygen evolution reaction catalyst Co (OH) 2 were used as the system. The selective oxidation of the optoelectronic catalyst for the oxidation of glycerol was carried out by BiVO4. The effects of the pH value and bias of the solution on the selectivity of the organic reaction were studied. The results showed that the yield and selection of the two hydroxy acetone and the high value products under the acid strip were obtained. Selectivity, Faraday efficiency is the highest, can get 50% light radical acetone selectivity up to 50%, the yield up to 55.92mmol/g/h of the catalytic effect (1.2Vvs RHE, H type electrolyzer).H+ concentration affects the reaction path, the selectivity of the product, added bias can be better to increase the carrier separation capacity, increase the current density, does not affect the reaction path selection. In addition, the effect of the plasmon effect and the Co (OH) 2 material on the catalytic properties of the noble metal nanostructures in the neutral reaction liquid have been studied. The research foundation for the production of high value chemical products by the efficient selective catalytic oxidation of solar energy is based on the N silicon nanowire -PEDOT:PSS (poly (3,4- ethanoxy thiophene) - poly (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - poly (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) - (benzene) Inorganic organic heterojunction type photovoltaic devices and N silicon nanowire -rGO (reduced graphene oxide) Schottky type photovoltaic devices are used as the system to study the mechanism of the photoelectric conversion efficiency of the photovoltaic devices in near infrared region with the equal ionization of the plasmon polaritons in the near infrared region, and the design of this mechanism is designed. Flexible photovoltaic devices. Metal Ag nanoscale excites plasmon in near infrared region and produces thermal electrons. It is found that when silver nanoscale is directly exposed to N type silicon nanowires, that is, hot electrons are injected directly into the guide band of silicon, which can greatly increase the efficiency of photovoltaic conversion, especially in the near infrared region, as an example of 800nm. It is improved by 59%. By constructing N and P type silicon nanowire based photovoltaic devices respectively, the mechanism of the effect of the equal ionization thermal electron enhancement effect in the photovoltaic devices is analyzed. Based on this mechanism, we have prepared the flexible near infrared efficiency enhanced photovoltaic devices by micro nano processing. The surface design provides the basis for precision manufacturing, and constructs a new interface engineering idea for efficient photoelectric conversion.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1

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