光控碘化铅表面极性及其催化性能研究

发布时间：2018-07-10 08:36

本文选题：PbI_2 + 表面光电压　；参考：《西南交通大学》2017年硕士论文

【摘要】：随着社会经济的发展,一系列的环境问题接踵而来,如何充分地利用能源而又有效地降解污染已经成为解决问题的重点,而具有光伏效应和光催化能力的半导体材料就成为解决问题的突破点。半导体材料产生光伏响应并参与光催化过程主要依靠于光生电荷分离、迁移及复合过程。以上光生电荷的行为一般发生在半导体的表面,研究半导体表面光电性质可以引导光伏响应和光催化效率的提高。PbI_2为p型半导体材料,禁带宽度较大,约为2.4 eV。具有较高的原子系数、较大的禁带宽度、电阻率高和载流子迁移率寿命极大等诸多优点,能有效的利用太阳能,具有在光伏、检测器、传感器和光催化中的应用的潜力。由于其光生电荷的产生、传输和复合机理研究甚少,严重限制了 PbI_2的应用。基于以上原因,本文针对退火前后的PbI_2微晶,采用表面光电压(SPV)、场致光电压(FISPV)和瞬态光电压(TPV)技术对以上光生电荷行为进行研究。并通过部分样品的光催化MO实验,查找光生电荷行为和光催化结果的内在联系。本课题以退火前后PbI_2微晶的制备及性能研究和不同退火时间对PbI_2的表面改性两个方面来展开的:1、采用溶液法来制备出PbI_2微晶,禁带宽度为2.39 eV。PbI_2微晶的表面存在捕获空穴的表面态,致使亚带隙光照下光伏反转现象的发生,对应的表面态位于价带上方0.43 eV。表面光电压在不同波长光照下光生电荷产生方式不同,遮光后对应的光电压衰减时间也不同,这就导致了不同的MO光催化结果。2、将PbI_2微晶在520 K真空条件下分别退火10 min、20 min和30 min,退火后样品的原子配比(Pb:I)更接近1:2。PbI_2微晶在退火后样品的的光谱吸收范围有所扩展,带隙随退火时间的延长越来越大。退火导致表面缺陷减少,但增大了在场致作用下的反型层作用,外加偏压越大,反型层的作用也逐渐加强,甚至超过了本征的带带跃迁作用。
[Abstract]:With the development of society and economy, a series of environmental problems are coming. How to make full use of energy and degrade pollution effectively has become the key to solve the problem. Semiconductor materials with photovoltaic effect and photocatalytic ability become the breakthrough point to solve the problem. The photovoltaic response of semiconductor materials and their participation in photocatalytic process mainly depend on the photocharge separation, migration and recombination process. The photoinduced charge behavior usually occurs on the surface of the semiconductor. The photovoltaic response and photocatalytic efficiency of the semiconductor can be improved by studying the photovoltaic properties of the semiconductor surface. PbIStack2 is a p-type semiconductor material with a wide bandgap of about 2.4 EV. It has many advantages, such as high atomic coefficient, large band gap, high resistivity and great carrier mobility life. It can effectively utilize solar energy and has potential in photovoltaic, detector, sensor and photocatalytic applications. Due to the generation of photogenerated charge, there are few studies on the transport and recombination mechanism, which seriously limits the application of PbIAP2. For the above reasons, surface photovoltage (SPV), field photovoltage (FISPV) and transient photovoltage (TPV) were used to study the photoinduced charge behavior of PbI2 microcrystals before and after annealing. The internal relationship between photocatalytic charge behavior and photocatalytic results was found through the photocatalytic MO experiments of some samples. In this paper, the preparation and properties of PbISAT _ 2 microcrystals before and after annealing and the surface modification of PBI _ s _ 2 by different annealing time were used to prepare PbI-2 microcrystals by solution method. The gap width of 2.39eV.PbI2 microcrystal has a surface state of trapped holes, which results in photovoltaic inversion under sub-band gap illumination. The corresponding surface state is 0.43 EV above the valence band. The photovoltage of surface photovoltage is produced in different ways under different wavelengths of illumination, and the attenuation time of photovoltage after shading is also different. This resulted in different MO photocatalytic results .2.The microcrystals were annealed at 520K vacuum for 10 min ~ 20 min and 30 min, respectively. The atomic ratio (Pb: I) of the annealed samples was closer to 1: 2. The absorption range of PbI _ 2 microcrystals increased after annealing. The band gap increases with the increase of annealing time. Annealing results in the reduction of surface defects, but increases the effect of the inversion layer under the field action. The greater the bias, the stronger the effect of the inversion layer is, even more than the band transition of the intrinsic band.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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