ZnSe和ZnSe:Mn量子点的水相制备及其在ZnO太阳能电池中的应用

发布时间：2018-05-14 21:16

  本文选题：量子点 + 荧光性能　； 参考：《广西大学》2014年硕士论文

【摘要】：随着工业的迅猛发展,能源问题日益突出,人类迫切需求一种可再生能源代替化石能源。由于太阳能电池能够把太阳能直接转换成光能,而且发电过程中不会造成环境污染,因而受到人们越来越多的关注。其中,敏化太阳能电池因其制备方法简单、光电转换效率高等优点,成为了太阳能电池的研究的热点和重点。目前,有机染料作为敏化剂所取得的效率最高,但因有机染料存在价格昂贵,长期稳定性差等缺点,限制了其在敏化电池上的应用。而荧光量子点制备方法简单廉价,具有量子限域效应及较大的消光系数,且稳定性好,因而能够成为一种替代有机染料的光敏材料。 本论文采用巯基水相法分别合成了ZnSe和ZnSe:Mn量子点,并通过透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)、紫外光谱仪以及荧光光谱仪等测试手段分别对所得样品的形貌尺寸、晶体结构、吸收光谱以及发射光谱进行了表征。其次,利用水热法制备了ZnO纳米棒阵列,并以此作为电池载体材料,将之前实验所得的ZnSe和ZnSe:Mn纳米晶作为不同的光敏化剂,通过直接吸附法(DA)将两者组装成量子点敏化太阳能电池器件,分别讨论了ZnSe沉积时间、沉积温度和ZnSe:Mn沉积时间、沉积温度对ZnO太阳能电池的光电性能的影响。主要研究内容及结论为： (1)以SeO2为硒源,通过一步法合成了水溶性的ZnSe量子点。探讨了稳定剂种类及用量、反应时间、Zn/Se摩尔比例、体系初始pH值对ZnSe量子点光学性质的影响。所得的巯基乙酸(TGA)包裹的ZnSe量子点具有最佳的荧光性能,最高量子产率达到了12.8%。其发光区域在蓝绿光范围内；紫外吸收峰相对于体材料发生了一定程度的蓝移；量子点颗粒为近球形,尺寸大约为3-4nm,呈闪锌矿立方晶型。 (2)以半胱氨酸(L-cys)为稳定剂,通过一种新颖的绿色合成方法在水溶液中制备了Mn离子掺杂的ZnSe量子点。研究发现反应时间、Mn的掺杂量、Zn/Se摩尔比例及初始pH值对ZnSe:Mn量子点的荧光性能有很大影响。在最佳实验条件下生成的ZnSe:Mn量子点为立方晶型,粒径约4-5nm,紫外吸收峰强度大于未掺杂的ZnSe量子点,最大荧光量子产率达7.2%,其发光位于白光区域,CIE坐标为(x=0.34,y=0.32)。 (3)采用水热法通过优化制备工艺条件,制备出了形貌规则和性能最佳的ZnO纳米棒阵列。再利用DA法在ZnO纳米棒阵列上分别沉积ZnSe和ZnSe:Mn量子点,即得量子点敏化的ZnO太阳能电池。研究发现当ZnSe沉积时间和沉积温度分别为5h和60℃时,ZnO太阳能电池的光电性能最佳,其转化效率达到0.100%。短路电流1.392mA·cm-2,开路电压0.391V,填充因子0.183。而当ZnSe:Mn沉积时间和沉积温度分别为3h和60℃时,ZnO太阳能电池的光电转化效率最高则可达到0.280%,此时光电流密度为2.245mA·cm-2,开路电压达到0.670V,填充因子O.182。
[Abstract]:With the rapid development of industry, the problem of energy is becoming more and more serious, and mankind urgently needs a kind of renewable energy to replace fossil energy. People pay more and more attention to solar cells because they can convert solar energy directly into light energy and will not cause environmental pollution in the process of power generation. Among them, sensitized solar cells have become the focus of solar cell research because of the advantages of simple preparation method and high photoelectric conversion efficiency. At present, the efficiency of organic dyes as sensitizer is the highest, but the application of organic dyes in sensitized batteries is limited because of their high price and poor long-term stability. On the other hand, the preparation method of fluorescent quantum dots is simple and cheap, with quantum limiting effect, large extinction coefficient and good stability, so it can be used as a substitute for organic dyes Guang Min materials. In this paper, ZnSe and ZnSe:Mn quantum dots were synthesized by sulfhydryl aqueous phase method, and the morphology and crystal structure of the samples were measured by TEM, UV and fluorescence spectrometer, respectively, by means of transmission electron microscope (TEM), X-ray powder diffractometer (XRD), UV spectrometer and fluorescence spectrometer. Absorption spectra and emission spectra were characterized. Secondly, ZnO nanorod arrays were prepared by hydrothermal method and used as carrier materials for battery. ZnSe and ZnSe:Mn nanocrystals obtained from previous experiments were used as different Guang Min agents. The quantum dot-sensitized solar cell devices were assembled by direct adsorption method. The effects of ZnSe deposition time, deposition temperature, ZnSe:Mn deposition time and deposition temperature on the photovoltaic properties of ZnO solar cells were discussed. The main contents and conclusions are as follows: Using SeO2 as selenium source, water-soluble ZnSe quantum dots were synthesized by one step method. The effects of the type and amount of stabilizer, the reaction time and the molar ratio of Zn- / se, the initial pH value of the system on the optical properties of ZnSe QDs were discussed. The ZnSe quantum dots coated with thioglycolic acid have the best fluorescence properties with the highest quantum yield of 12.8g. The luminescence region is within the range of blue-green light, the UV absorption peak is blue shifted to some extent relative to the bulk material, and the quantum dot particle is nearly spherical, with a size of about 3-4 nm, showing the cubic crystal form of sphalerite. Using cysteine L-cys) as stabilizer, Mn-doped ZnSe quantum dots were prepared in aqueous solution by a novel green synthesis method. It is found that the molar ratio of Zn / se and initial pH have great influence on the fluorescence properties of ZnSe:Mn quantum dots. Under the optimum experimental conditions, the ZnSe:Mn quantum dots are cubic crystal with a diameter of about 4-5 nm. The UV absorption peak intensity is higher than that of the undoped ZnSe quantum dots, and the maximum fluorescence quantum yield is 7.2. The ZnO nanorod arrays with the best morphology and properties were prepared by hydrothermal method. Then the ZnSe and ZnSe:Mn quantum dots were deposited on the ZnO nanorods array by DA method. The ZnO solar cells sensitized by quantum dots were obtained. It is found that the photovoltaic properties of ZnSe solar cells are the best when the deposition time and deposition temperature are 5 h and 60 鈩，

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