兰州大学机构库 >材料与能源学院
改善全无机CsPbI2Br钙钛矿太阳电池光伏性能和稳定性研究
Alternative TitleStudy on improving the photovoltaic performance and stability of all-inorganic CsPbI2Br perovskite solar cells
陈秋露
Subtype硕士
Thesis Advisor贺德衍
2023-05-31
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name工学硕士
Degree Discipline材料学
KeywordCsPbI2Br钙钛矿太阳电池 CsPbI2Br perovskite solar cell 添加剂工程 additive engineering 界面缺陷钝化 passivated interface layer 稳定性 stability
Abstract

钙钛矿材料由于具有高的光吸收系数、大的载流子迁移率和低成本的制备方法而备受关注,无机钙钛矿材料CsPbI2Br还具有较强的光热稳定性。近年来,越来越多的研究者致力于该体系的太阳电池研究,在短短的几年内,CsPbI2Br钙钛矿太阳电池的换换效率有很大的提升。尽管如此,目前报道的效率与其理论极限值依然有一定的差距,这是由于所制备的CsPbI2Br薄膜通常有大量的内部和表面缺陷,光生载流子复合严重。此外,光吸收层与电荷传输层之间的能级不匹配也是载流子损失的重要原因,器件的长期稳定性也是钙钛矿太阳电池研究需要关注的重大问题之一。基于此,本论文聚焦CsPbI2Br钙钛矿薄膜,通过添加剂工程和界面缺陷钝化改善CsPbI2Br钙钛矿薄膜的性能及其太阳电池的光伏性能和稳定性。具体研究内容如下:

(1)将氮掺杂石墨烯量子点(N-GQDs)添加到CsPbI2Br钙钛矿薄膜中。由于存在大量的有机官能团,N-GQDs能够与钙钛矿中未配位的Pb2+和I-/Br-发生作用,从而起到钝化CsPbI2Br中的晶界和表面缺陷的作用,最终获得表面平整、缺陷密度低的CsPbI2Br钙钛矿薄膜。同时,具有良好导电性的N-GQDs在晶界处起到电子桥作用,有助于光生电子输运到电子传输层,抑制了在晶界处的复合。所制备的CsPbI2Br钙钛矿太阳电池的转换效率达到14.39%。

(2)将N-GQDs和NaCl同时添加到CsPbI2Br钙钛矿薄膜中。由于Cl原子与Br原子有着相似的物理化学性质,Cl原子进入钙钛矿结构后会部分取代Br原子,从而改变CsPbI2Br的电子能级结构,使其价带顶和导带底能级均上移,CsPbI2Br的能级与P3HT的能级更匹配,光生空穴克服更低的能量势垒便可输运到空穴传输层。N-GQDs和NaCl的同时添加能够协同促进载流子在CsPbI2Br钙钛矿太阳电池中的传输和提取,获得了15.37%的转换效率。

(3)在CsPbI2Br钙钛矿薄膜上涂覆一层极薄的聚甲基丙烯酸甲酯(PMMA)。一方面,PMMA聚合物长链上有许多官能团,可以钝化CsPbI2Br钙钛矿薄膜表面的缺陷,提升CsPbI2Br钙钛矿太阳电池的转换效率,另一方面,玻璃化的PMMA具有强疏水性,可以隔绝大气中的水分子对光吸收层的侵蚀,增加CsPbI2Br的湿度稳定性。同时,PMMA还可以减少Ag电极中的Ag与CsPbI2Br钙钛矿薄膜中的I离子之间相互扩散,避免AgI的生成。

Other Abstract

Perovskite materials have attracted much attention due to their high optical absorption coefficient, long carrier mobility and low-cost preparation methods. Inorganic CsPbI2Br perovskite also has the advantages of appropriate band gap and strong photothermal stability. In recent years, more and more researchers began to focus on the solar cell research of this system, and the photoelectric conversion efficiency (PCE) of CsPbI2Br perovskite solar cells has made a great improvement in just a few years. However, there is difference between the reported efficiency and its theoretical limit value. This is because the perovskite films are usually accompanied by a large number of internal defects and surface defects, leading to carrier recombination. In addition, the energy level mismatch between the optical absorption layer and the charge transfer layer is also one of the reasons for carrier loss. The long-term stability of devices is also a very important point in the research of perovskite solar cells. Based on the above problems, this paper mainly takes focus on CsPbI2Br perovskite films to improve the photoelectric performance and stability of CsPbI2Br perovskite solar cells through additive engineering and interface defect passivation. The specific research contents are as follows:

(1) Nitrogen-doped graphene quantum dots (N-GQDs) were added to CsPbI2Br perovskite films. Due to a large number of organic functional groups, N-GQDs can interact with the uncoordinated Pb2+and I-/Br-in perovskite, achieving the function of passivating the grain boundary and surface defects of the light absorption layer, and finally obtaining CsPbI2Br perovskite film with flat morphology and low defect density. At the same time, N-GQDs with good conductivity play the role of electronic bridge in the grain boundary, which can help the photogenerated electrons to transfer smoothly to the electron transport layer, reducing the recombination at the grain boundary, and the devices with N-GQDs achieve 14.39% PCE.

(2) N-GQDs and NaCl were added to the perovskite layer at the same time. Because of similar physical and chemical properties, Cl will partially replace the position of Br after entering the perovskite structure. Cl-doping aligns the energy level of CsPbI2Br, decreasing the energy barrier between perovskite and P3HT, so that the photogenerated hole can reach the hole transport layer only by overcoming the lower energy barrier. N-GQDs and NaCl can synergistically promote the transport and extraction of carriers in CsPbI2Br perovskite solar cells. And finally the devices with binary additives achieved 15.37% PCE.

(3) A ultra-thin polymethylmethacrylate (PMMA) layer is covered on the CsPbI2Br pervoskite layer. The long chain of PMMA polymer has many functional groups, which can passivate the defects on the perovskite surface, promoting the power conversion efficiency of CsPbI2Br perovskite solar cells. On the other hand, the vitrified PMMA has strong hydrophobicity, which can insulate the water molecules in the air from the erosion of the light absorption layer and increase the humidity stability of the material. At the same time, PMMA can also reduce diffusion of I ions in perovskite and Ag electrode, avoiding the generation of AgI.

MOST Discipline Catalogue工学 - 材料科学与工程 - 材料学
URL查看原文
Language中文
Other Code262010_220200936080
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/536198
Collection材料与能源学院
Affiliation
兰州大学材料与能源学院
Recommended Citation
GB/T 7714
陈秋露. 改善全无机CsPbI2Br钙钛矿太阳电池光伏性能和稳定性研究[D]. 兰州. 兰州大学,2023.
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