钙钛矿太阳能电池的性能优化以及界面电荷对器件的影响

发布时间：2018-04-08 15:13

本文选题：钙钛矿太阳能电池　切入点：离子移动　出处：《北京交通大学》2017年硕士论文

【摘要】：有机-无机钙钛矿太阳能电池因为其低成本易制备高效率等特点,在过去的几年中引起了广泛关注,进一步提高其效率和稳定性是研究工作者们都在进行的工作。通过对制备方法和处理方法的改进,目前关于钙钛矿太阳能电池的报道中提到其最高效率已超过22%,在测试过程中产生的电流-电压回滞问题却始终影响稳定性。关于效率和稳定性,本文中做了相关研究,具体分为两个部分:1、首先我们对器件的制备方法进行了探索和研究。通过一步法和两步法来制备钙钛矿晶体薄膜并进行比较,发现活性层的反应情况、结晶情况和表面形貌对器件的影响很大,经过尝试找到了能够适合我们工作的高效率器件的制备方式;通过改变器件的空穴传输层和电子传输层等工作,发现合适电子/空穴传输层对于器件有促进作用,选定NiOx和PCBM作为空穴传输层和电子传输层。经过各种优化,将效率从开始的3%提高到了 15%。2、在对机理的探究中,我们发现不同形貌度的器件性能不同,表面粗糙器件往往伴随着很大的电流-电压回滞,表面光滑的器件只有很小的回滞,而这种电流-电压回滞可以靠调节PCBM薄膜厚度来消除。据报道,回滞的产生是因为界面电荷的聚积,这种聚积引起了界面处的能带弯曲,从而影响电荷的输运和收集。有意思的是,表面粗糙的器件界面电荷的密度也很大。联系这一切,我们提出了一种模型来解释以上的现象:界面电荷的聚积和界面处的电容息息相关,电容越大,聚积的电荷越多。粗糙的表面造成较大的电容相对面积,同时,PCBM太薄会导致电容两极板距离过近,这都是界面电容很大的原因,得到的实验数据支持了这个结论。界面的电容可以靠更光滑的表面和厚度合适的PCBM层来减小,从而削弱界面电荷的聚积,借此来提高器件的效率同时减少电流-电压回滞。
[Abstract]:Organic-inorganic perovskite solar cells have attracted much attention in the past few years because of their low cost and high efficiency.Through the improvement of the preparation method and the treatment method, the report on the perovskite solar cell mentioned that its maximum efficiency has exceeded 222.The current-voltage hysteresis problem has always affected the stability.As to the efficiency and stability, this thesis is divided into two parts: 1. Firstly, we study the fabrication methods of the devices.The perovskite crystal films were prepared by one-step method and two-step method and compared. It was found that the reaction of the active layer, the crystallization and the surface morphology had a great influence on the device.By changing the hole transport layer and electron transport layer of the device, we find that the appropriate electron / hole transport layer can promote the device.NiOx and PCBM are selected as hole transport layer and electron transport layer.After various optimizations, the efficiency was raised from 3% to 15.2. In the study of the mechanism, we found that the performance of the devices with different morphologies is different, and the surface roughness devices are often accompanied by large current-voltage hysteresis.The smooth surface of the device has only a small hysteresis, which can be eliminated by adjusting the thickness of the PCBM film.It is reported that hysteresis is caused by the accumulation of interfacial charges, which results in the bending of energy bands at the interface, which affects the transport and collection of charges.Interestingly, the surface roughness of the device interface charge density is also very large.In connection with all this, we propose a model to explain the above phenomena: the accumulation of interface charges is closely related to the capacitance at the interface, and the larger the capacitance, the more the accumulated charge.The large capacitance relative area caused by rough surface and too thin PCBM will lead to the close distance of the capacitor bipolar plate, which is the reason for the large interface capacitance. The experimental data support this conclusion.The capacitance of the interface can be reduced by a smoother surface and an appropriate thickness of PCBM layer, thus weakening the accumulation of the interface charge, thereby improving the efficiency of the device and reducing the current-voltage hysteresis.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM914.4

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