钙钛矿太阳能电池中界面电子结构的研究

发布时间：2017-12-28 02:27

本文关键词：钙钛矿太阳能电池中界面电子结构的研究　出处：《中国科学院研究生院(上海应用物理研究所)》2017年博士论文　论文类型：学位论文

【摘要】：近年来,有机-无机材料杂化的钙钛矿太阳能电池由于其优异的光电性质和简单的制备方法而得到越来越广泛的关注,其光电转换效率在短短的几年时间内从3.8%上升至22.1%,显示出很强的商业化前景。转换效率的迅速提升,一方面得益于钙钛矿旋涂成膜工艺改进和器件结构的发展、另一方面得益于钙钛矿薄膜界面优化和新型电荷传输层的开发等方面的进步。然而钙钛矿太阳能电池在商业化发展过程中,仍然还存在着几个需要克服的难点:环境稳定性差、原料毒性、电池面积小、成本控制等。令人鼓舞的是,华中科技大学的韩宏伟教授首次制备出了100平方厘米大面积可印刷式的钙钛矿太阳能电池器件,光电转换效率可以达到10.4%,1000小时光照条件下,器件的性能没有明显的衰减,显示出极大的商业化潜力。尽管人们在钙钛矿太阳能电池效率以及稳定性的发展上已经取得了重大的突破,但是由于有机界面存在和无机半导体理论不同的界面偶极、电荷极化、能带弯曲等现象,而合适的界面能级关系到器件最终的性能,因此有必要对该钙钛矿界面电子结构进行深入的研究以进一步理解其深层的物理机制并继续推动钙钛矿太阳能电池的进一步发展。本文主要通过X射线光电子能谱(XPS)、紫外光电子能谱(UPS)以及同步辐射掠入射X射线衍射(GIXRD)等手段,对钙钛矿薄膜的制备工艺(前驱体比例、胍盐(GA)掺杂)、以及并五苯(Pentacene)和红荧烯(Rubrene)空穴传输层和钙钛矿层之间界面电子结构以及制备Rubrene/PEDOT:PSS钙钛矿太阳能电池器件,采用复合空穴传输层以提高器件效率等方面进行了系统的研究。主要研究内容以及研究成果如下:1、前驱体比例对钙钛矿薄膜形貌、晶体结构及电子结构影响的研究研究了钙钛矿薄膜制备时,其前驱体溶液中甲氨碘(CH_3NH_3I)和碘化铅(PbI_2)按照不同比例,对旋涂得到的钙钛矿薄膜的形貌、结构、电子结构的影响,并制备了相应的器件,发现适当提高前驱体溶液中CH_3NH_3I的比例,可以提高钙钛矿太阳能电池的部分器件性能。2、钙钛矿A位胍盐掺杂对钙钛矿薄膜的形貌结构电子结构的影响的研究通过对甲胺铅碘钙钛矿的有机配体掺杂,以合适的比例将胍盐和甲胺混合制备出钙钛矿薄膜,研究有机配体掺杂对钙钛矿薄膜的形貌结构电子结构的影响。3、Pentacene/CH_3NH_3PbI_3和Rubrene/CH_3NH_3PbI_3界面电子结构研究通过XPS/UPS原位(in-situ)地对并五苯Pentacene/CH_3NH_3PbI_3和红荧烯Rubrene/CH_3NH_3PbI_3界面的能级结构做了系统的研究,发现在有机太阳能电池中常用作空穴传输层地这两种分子在能级上和钙钛矿地能级相匹配,在并五苯Pentacene/CH_3NH_3PbI_3和红荧烯Rubrene/CH_3NH_3PbI_3界面处,在并五苯侧和红荧烯侧都形成了向下(down-word)的能带弯曲,这种能带弯曲的形式有利于空穴在界面的提取,同时两种分子的最低未占据态分子轨道能级(LUMO能级)有比较高,可以有效地阻碍电子向空穴传输层传输,以降低电子-空穴在界面处复合的几率。这些结果有助于了解载流子在界面的传输机制。4、红荧烯作为空穴传输层的钙钛矿太阳能电池器件的制备和表征制备了红荧烯作为空穴传输层的钙钛矿太阳能电池器件,最终通过使用PEDOT:PSS/Rubrene作为复合空穴传输层,钙钛矿太阳能电池最高得到了13.52%的转换效率。这主要是因为PEDOT:PSS虽然具有良好的成膜性,但是功函数不是理想的,然而红荧烯尽管能级匹配效果好,能带弯曲利于空穴收集和阻挡电子注入,但成膜性不好;因此,采用复合传输层,同时利用PEDOT:PSS成膜性和红荧烯能级匹配的优势,可有效提升器件的效率。但由于红荧烯的载流子传输效率远比PCBM的高,所以会形成比较显著的J-V曲线滞后效应。
[Abstract]:In recent years, perovskite solar cell organic inorganic hybrid materials due to its excellent optical properties and simple preparation method and get more and more attention, the photoelectric conversion efficiency in just a few years time increased from 3.8% to 22.1%, showing a strong commercial prospects. The rapid improvement of conversion efficiency is due to the improvement of perovskite spin coating process and the development of device structure. On the other hand, it is benefited from the optimization of perovskite membrane interface and the development of new charge transport layer. However, there are still several difficulties to overcome in the commercialization development of perovskite solar cells: poor environmental stability, raw material toxicity, small battery area, and cost control. Encouragingly, Huazhong University of Science and Technology professor Han Hongwei prepared for the first time a large area can be 100 square centimeters of perovskite solar cell devices, printing type, photoelectric conversion efficiency can reach 10.4%, 1000 hours light condition, the performance of the device without obvious attenuation, which shows the great potential for commercialization. Although people in the perovskite solar cell efficiency and stability and development has achieved a major breakthrough, but due to the organic interface and the interface dipole, different inorganic semiconductor theory charge polarization, band bending phenomenon, but the right level related to the final interface device performance, so it is necessary to further the development of in-depth study the electronic structure of perovskite interface to further understanding of the underlying physical mechanism and continue to promote the perovskite solar cell. This paper mainly through X ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) and synchrotron radiation grazing incident X ray diffraction (GIXRD) and other means, the preparation process of Perovskite Thin Films (precursor ratio, guanidine salt (GA), and five doping) and benzene (Pentacene) and rubrene (Rubrene) the hole transport layer and perovskite interface between electronic structure and preparation of Rubrene/PEDOT:PSS perovskite solar cell devices were studied using composite hole transporting layer to improve the efficiency of the device. The main research contents and results are as follows: 1. Study on the effect of precursor ratio on perovskite film morphology, crystal structure and electronic structure of Perovskite Thin Films during preparation of the precursor solution of ammonia iodine (CH_3NH_3I) and lead iodide (PbI_2) in different proportions, affect the morphology, structure, electronic structure of Perovskite Thin Films get on the spin coating, and the preparation of the corresponding device, find the appropriate increase of CH_3NH_3I in the precursor solution ratio can improve device performance of perovskite solar cell. Study on the effect of 2, A perovskite guanidine salt doping on the morphology and structure of Perovskite Thin film electronic structure of perovskite organic ligands lead methylamine iodine doped with appropriate proportion of guanidine salt and methylamine mixed preparation of Perovskite Thin film, effects of organic ligands on the morphology of Thin Film Doped Perovskite Structure electronic structure. 3, Pentacene/CH_3NH_3PbI_3 and Rubrene/CH_3NH_3PbI_3 interface electronic structure was studied by XPS/UPS in situ (in-situ) to do a systematic research on the structure and level of five - Pentacene/CH_3NH_3PbI_3 and rubrene Rubrene/CH_3NH_3PbI_3 interface, found in organic solar cells are commonly used as hole transport layer of the two kinds of molecular level and match in perovskite to level, and in five - Pentacene/CH_3NH_3PbI_3 and rubrene Rubrene/CH_3NH_3PbI_3 interface, and five in benzene side and rubrene side (down-word) formed a downward band bending, the band bending form to a hole in the interface extraction, and two molecules of the lowest unoccupied molecular orbital energy state (LUMO level) there is relatively high, can effectively block the electron transfer to the hole transport layer, in order to reduce the electron hole recombination at the interface. These results help to understand the transmission mechanism of the carrier at the interface. 4, rubrene perovskite solar cell devices as a hole transport layer, the preparation and characterization of preparation of rubrene as perovskite solar cell devices, a hole transport layer, finally by using PEDOT:PSS/Rubrene as a composite hole transporting layer, perovskite solar cell conversion efficiency of 13.52% has been the highest. This is mainly because the PEDOT:PSS has a good film, but the function is not ideal, however, although the level of rubrene effect, band bending for hole collection and electron injection barrier, but the film is not good; therefore, the composite transmission layer, and a matching film and red. The advantage of using graphene level PEDOT:PSS, can effectively improve the efficiency of the device. However, the carrier transmission efficiency of the red fluorenes is much higher than that of the PCBM, so the lagging effect of the J-V curve is significant.
【学位授予单位】：中国科学院研究生院(上海应用物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM914.4

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