钙钛矿太阳能电池电子传输层与界面研究

发布时间：2018-04-09 03:25

本文选题：钙钛矿太阳能电池　切入点：电子传输层　出处：《中国科学院大学(中国科学院物理研究所)》2017年博士论文

【摘要】：钙钛矿太阳能电池因其优秀的吸光能力、简单的制备工艺、高的能量转化效率成为具有商业化应用前景的下一代太阳能电池之一。在钙钛矿电池中,电子传输材料和异质结界面与载流子的传输、复合过程紧密联系,严重影响着电池的性能。本论文的工作围绕钙钛矿太阳能电池的电子传输层以及界面展开,主要涉及了钙钛矿电池的准确性测量,新型电子传输层结构的的制备,钙钛矿电池中电子传输层异质结界面原子结构的研究,以及制备电子传输层的原子层沉积系统的设计、集成与搭建等,取得了以下成果:一、详细分析了钙钛矿太阳能电池中,测量蒙版(mask)的大小和实际电池的活性面积之间的比例对电池性能的准确评估的影响。研究了不同大小的蒙版面积(mask aperture)下钙钛矿太阳能电池的J-V特性,指出不同大小的非光照暗态面积会显著影响电池的开路电压。首次提出了一种双二极管的模型来模拟暗态电池和光照电池同时存在时对整体器件J-V测量结果的影响,利用阻抗谱和瞬态光电压衰减的手段证明如果mask小于电池活性面积会导致器件中增加的电荷复合途径,将会低估实际器件的开路电压(减少约10%)。最终的研究结果指明了一种准确评价钙钛矿性能的方法。二、首次提出制备了一种TiO_2/ZnO双层电子传输层的结构,这种双层结构结合了高的电子抽取性能和低的界面复合特点。在平面结构的钙钛矿太阳能电池中,由于使用了这种双层电子传输层,前表面复合过程得到了有效的抑制,获得了超过17%的光电转化效率,其中短路电流超过21mA/cm~2,开路电压1084 mV,填充因子0.75。该工作提供了一种简单的界面层处理方法用来获得高效率的钙钛矿电池。三、与中科院物理所谷林研究员合作,利用球差矫正电子显微镜研究了钙钛矿电池中TiO_2/MAPbI_3异质结界面,发现这个界面存在一个单原子层厚度的重原子层,是由于界面甲胺基团空位的存在所导致。配合第一性原理计算,表明这个异质结界面的MA基团缺失可以导致TiO_2和MAPbI_3之间更强原子间结合力,从而增强界面的稳定性。这个研究结果能够帮助进一步理解钙钛矿电池中的异质结界面原子排布与相互作用,为今后的界面处理提供理论指导。四、自主设计研制了实验室第一台原子层沉积设备,包括真空腔体、气路、电气控制的设计与控制软件的编写,具有单次反应时间小于50 ms,单次循环时间小于20s的快速响应特点。研制的原子层沉积设备被用于氧化物薄膜的制备和太阳能电池的界面处理。利用该设备,低温制备了ZnO、TiO_2电子传输层并应用于钙钛矿太阳能电池,获得了超过18%的光电转化效率。自主搭建的系统有效降低了成本,并投入到实验室的使用,成为一种薄膜制备的有效手段。
[Abstract]:Perovskite solar cells have become one of the next generation solar cells with commercial applications due to their excellent absorptivity, simple preparation process and high energy conversion efficiency.In perovskite batteries, the transport of electron transport materials and heterojunction surfaces with carriers is closely related to the recombination process, which seriously affects the performance of the battery.This paper focuses on the electron transport layer and interface of the perovskite solar cell. It mainly involves the measurement of the accuracy of the perovskite cell and the preparation of the new structure of the electron transport layer.The research on atomic structure of electron transport layer heterojunction surface in perovskite battery and the design, integration and construction of atomic layer deposition system for preparing electron transport layer have obtained the following achievements: first, the detailed analysis of perovskite solar cell,The effect of the ratio between the size of the mask and the active area of the actual battery on the accurate evaluation of the battery performance is measured.The J-V characteristics of perovskite solar cells under mask aperture with different sizes are studied. It is pointed out that the open circuit voltage is significantly affected by different sizes of non-illumination dark areas.A two-diode model is proposed for the first time to simulate the effect of the existence of both dark and light cells on the J-V measurement results of the whole device.By means of impedance spectroscopy and transient photovoltage attenuation, it is proved that if the mask is smaller than the active area of the cell, it will lead to the increase of the charge recombination path in the device, and the open circuit voltage of the actual device will be underestimated (about 10% reduction).The final results indicate an accurate method for evaluating perovskite properties.Secondly, a structure of TiO_2/ZnO double-layer electron transport layer is proposed for the first time, which combines the characteristics of high electron extraction performance and low interface recombination.In a planar perovskite solar cell, the composite process of the front surface is effectively suppressed by the use of this double-layer electron transport layer, and over 17% of the photoelectric conversion efficiency is obtained.The short circuit current exceeds 21 Ma / cm ~ 2, the open circuit voltage is 1084 MV, and the filling factor is 0.75.This work provides a simple interface layer processing method for high efficiency perovskite cells.Third, in cooperation with Gulin, a researcher at the Institute of Physics of the Chinese Academy of Sciences, the TiO_2/MAPbI_3 heterojunction interface in perovskite batteries has been studied using spherical aberration electron microscopy. It has been found that there is a heavy atomic layer with a single atomic layer thickness at the interface.This is due to the existence of interfacial methylamine group vacancies.The results of first-principles calculation show that the absence of MA group in the heterojunction interface can lead to a stronger interatomic bonding force between TiO_2 and MAPbI_3, thus enhancing the stability of the interface.The results of this study can help to further understand the arrangement and interaction of heterojunction atoms in perovskite cells and provide theoretical guidance for the interface treatment in the future.Fourth, the first atomic layer deposition equipment in the laboratory has been independently designed and developed, including the design and control software for vacuum chamber, gas path and electrical control.The reaction time is less than 50 Ms and the single cycle time is less than 20 s.The atomic layer deposition equipment has been developed for the preparation of oxide films and the interface treatment of solar cells.Using this equipment, ZnO- TiO2 electronic transport layer was prepared at low temperature and applied to perovskite solar cells. The photovoltaic conversion efficiency of more than 18% was obtained.The self-built system can effectively reduce the cost and be used in the laboratory. It has become an effective method for the preparation of thin films.
【学位授予单位】：中国科学院大学(中国科学院物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM914.4

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