量子点敏化太阳能电池结构调控及光伏性能研究

发布时间：2018-08-31 08:57

【摘要】：由于兼具高理论能量转换效率和低生产成本,作为第三代太阳能电池,量子点敏化太阳能电池已受到太阳能业界的广泛关注。然而,迄今为止,量子点敏化太阳能电池的光电转换效率与传统太阳能电池的相比仍有较大差距。本文以电池的结构和原理为基础,考虑量子点敏化电极的制备方法,量子点的能级调控,光阳极的材料性能对太阳能电池性能的影响,采用正交结构的TiO_2纳米粒子对ZnO纳米棒阵列进行修饰;采用原位还原法在TiO_2/ZnO纳米棒阵列光阳极引入等离激元Ag纳米颗粒;设计了一步连续离子层交互吸附与反应法制备能带可调的Cd-Zn-Se-S量子点敏化电极,系统研究了电池的性能。主要的研究内容分为以下三个方面:首先,为了减少氧化锌(ZnO)阵列表面的缺陷以降低电荷复合,利用H_3BO_3和(NH4)2TiF6溶液合成了正交结构的二氧化钛(TiO_2)纳米粒子并用其对ZnO纳米棒包覆,形成了复合纳米结构。该结构利用了纳米颗粒提供的大比表面积以及纳米棒优良的电子传输特性,以获得良好的电荷传输和光捕获能力。由于TiO_2修饰后的ZnO纳米棒阵列的表面复合中心(羟基)较少,因此ZnO纳米棒表面上发生的电荷俘获减少,从而降低了电荷复合,延长了电子寿命。最终,TiO_2修饰后太阳能电池的能量转换效率(PCE)达到4.80%,比未修饰电池的PCE(2.7%)提高78%。其次,为了提高光阳极的光俘获能力,在TiO_2/ZnO纳米棒阵列(NAs)引入Ag纳米粒子(NPs)构建量子点敏化太阳能电池(QDSC)。银纳米粒子的引入不仅增加了光俘获效率,促进激子解离,而且还降低了表面电荷复合,延长电子寿命,这些都有助于提高CdS/CdSe量子点(QDs)共敏化太阳能电池的短路电流密度(Jsc)。银纳米粒子与TiO_2纳米粒子直接接触使得费米能级朝着负电位上移,从而增加了电池的开路电压(Voc)。因此,Ag NPs修饰的TiO_2/ZnO NAS的PCE达到5.92%,比未修饰电池PCE(4.8%)提高了22%;最后,为了简化量子点沉积步骤,利用简易一步SILAR法在TiO_2多孔膜上沉积Cd-Zn-Se-S QDs制备光阳极。通过优化Cd~(2+)/Zn~(2+)和Se~(2-)/S~(2-)的比例,得到最优比,即:Cd~(2+)/Zn~(2+)=Se~(2-)/S~(2-)=0.3。通过TEM和XPS表征得出Cd-Zn-Se-S QDs由CdS、CdSe、ZnS、ZnSe这四种物质组成。UV-Vis测试表明循环次数的增加可提高光阳极的光吸收能力,有利于提高Jsc;EIS测试表明随着循环次数的增加,ZnSe和ZnS转变为CdSe和CdS,电荷复合增加,降低了Voc。当循环次数达到10时,Cd-Zn-Se-S QDs敏化的太阳能电池的PCE达到最大为5.62%。
[Abstract]:Because of its high theoretical energy conversion efficiency and low production cost, as the third generation solar cells, quantum dot-sensitized solar cells have been widely concerned by the solar industry. However, up to now, the photovoltaic conversion efficiency of QDs sensitized solar cells is much lower than that of traditional solar cells. In this paper, based on the structure and principle of the cell, the effects of the preparation method of quantum dot-sensitized electrode, the energy level regulation of quantum dot and the material performance of photoanode on the performance of solar cell are considered. The ZnO nanorod array was modified by orthogonal structure TiO_2 nanoparticles, and the isobaric Ag nanoparticles were introduced into the photoanode of TiO_2/ZnO nanorod arrays by in situ reduction method. The one-step continuous ion layer interaction adsorption and reaction method was designed to prepare the Cd-Zn-Se-S quantum dot-sensitized electrode with adjustable energy. The performance of the battery was systematically studied. The main research contents are as follows: firstly, in order to reduce the surface defects of zinc oxide (ZnO) arrays and reduce the charge recombination, orthogonal structure titanium dioxide (TiO_2) nanoparticles were synthesized by H_3BO_3 and (NH4) 2TiF6 solution and coated with ZnO nanorods. A composite nanostructure was formed. The structure takes advantage of the large specific surface area provided by nanoparticles and the excellent electron transport characteristics of nanorods in order to obtain good charge transport and optical trapping ability. Because the surface recombination centers (hydroxyl) of ZnO nanorods modified by TiO_2 are less, the charge trapping on ZnO nanorods decreases, which reduces the charge recombination and prolongs the electron lifetime. Finally, the energy conversion efficiency (PCE) of TiO2 modified solar cells reached 4.80, which was 78% higher than the PCE (2.7%) of unmodified cells. Secondly, in order to improve the photocapture ability of photoanode, quantum dot-sensitized solar cell (QDSC). Was constructed by introducing Ag nanoparticles (NPs) into TiO_2/ZnO nanorod array (NAs). The introduction of silver nanoparticles not only increases the phototrapping efficiency, promotes the exciton dissociation, but also reduces the surface charge recombination and prolongs the electron lifetime. These results are helpful to increase the short-circuit current density (Jsc). Of CdS/CdSe quantum dot (QDs) co-sensitized solar cells. The direct contact between silver nanoparticles and TiO_2 nanoparticles makes Fermi energy level move up to negative potential, thus increasing the open circuit voltage (Voc). Of the cell. Therefore, the PCE of TiO_2/ZnO NAS modified with Ag NPs is 5.92, which is 22% higher than that of unmodified PCE (4.8%). Finally, in order to simplify the step of quantum dot deposition, a simple one-step SILAR method is used to prepare the photoanode on the porous TiO_2 film. By optimizing the ratio of Cd~ (2) / Zn ~ (2) and Se~ (2-) / S ~ (2-), the optimal ratio is obtained, that is, the ratio of% CD ~ (2) / Zn ~ (2) / Zn ~ (2) / S ~ (2-) is 0.3. The results of TEM and XPS showed that Cd-Zn-Se-S QDs was composed of CdS,CdSe,ZnS,ZnSe. UV-Vis showed that the increase of cycle times could improve the photoabsorption ability of photoanode. The results of Jsc;EIS test showed that with the increase of cycle times, ZnSe and ZnS changed into CdSe and CdS, charge compound increase, and Voc. decreased. The maximum PCE of the solar cell sensitized by Cd-Zn-Se-S QDs is 5.62 when the cycle number reaches 10:00.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.4

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