摘 要

作为最新一代的太阳能电池，钙钛矿太阳能电池发展迅速，其光电转化效率已经提高到23.3%。有机金属卤化物钙钛矿层是具有极大发展潜力的光伏材料，它们具有高载流子迁移率，优异的吸收系数和带隙稳定性，长扩散长度以及低成本等优点。然而，有机金属卤化物钙钛矿层并不稳定，使钙钛矿太阳能电池难以大规模商业化应用。水分是降低钙钛矿稳定性的主要因素之一，这是因为有机甲基铵阳离子通过氢键在铅和碘化物的离子笼内弱结合，而氢键很容易被水分子破坏，从而加速钙钛矿材料的分解，破坏钙钛矿的结构，最终影响光伏器件的性能。

因此，提高钙钛矿太阳能电池的稳定性至关重要。聚合物封装薄膜能够同时应用于普通和柔性钙钛矿太阳能电池，具有重要的研究价值。本文通过选用聚乙二醇（PEG）、聚乙烯醇（PVA）、聚苯乙烯（PS）、聚甲基丙烯酸甲酯（PMMA）、聚甲基丙烯酸丁酯（PBMA）、聚乙烯基吡咯烷酮（PVP）六种不同的聚合物材料，溶解后旋涂成膜对钙钛矿进行封装，然后用紫外可见吸收光谱监测钙钛矿的分解进程。主要探究了聚合物分子量，亲疏水性，膜的厚度以及分子结构对钙钛矿封装效果的影响。主要研究成果如下：

（1）选取分子量为6000的PEG配制不同浓度的溶液涂膜，用椭圆偏光仪测量浓度与纯聚合物涂层厚度的关系。用不同厚度的涂层对钙钛矿进行封装，结果表明，膜厚对聚合物的封装效果产生影响不大。

（2）选取分子量分别为600、6000、35000的PEG对钙钛矿层封装，结果表明，分子量越小，氧含量越大，涂层能够与更多的水分子形成氢键，封装效果越差。

（3）通过水接触角测量仪测纯聚合物涂层的水接触角，比较不同聚合物涂层的亲疏水性。用不同亲疏水性的聚合物涂层对钙钛矿进行封装，结果表明，疏水性的聚合物封装效果明显好于亲水性聚合物。

（4）对几种疏水性聚合物的封装效果进行比较发现，其封装效果受聚合物本身的分子结构影响更大，聚合物支链越短，分子间空隙越小，膜越致密，封装效果越好。

关键词：钙钛矿；聚合物；封装；稳定性

Abstract

As the latest generation of solar cells, perovskite solar cells have been developed rapidly while their photoelectric conversion efficiency has been increased to 23.3%. The organometallic halide perovskites are promising photovoltaic materials owing to their advantages such as high carrier mobility, excellent absorption coefficient, bandgap tenability, long diffusion length, and low material cost. However, the organometallic halide perovskites are unstable, making it difficult for their large-scale commercial applications. Moisture is one of the main factors that reduce the stability of perovskites, which will accelerate the decomposition process of the perovskite material, then destroy the structure of the perovskite, and finally affect the performance of the photovoltaic device.

Encapsulation is an important method to improve the stability of perovskite solar cells. The polymer encapsulation indicates great superiority among other encapsulations as it can be applied to both ordinary and flexible perovskite solar cells. In this work, six different polymer materials such as PEG, PVP, PVA, PBMA, PMMA and PS were selected to encapsulate perovskites by spin-coating. The degradation process of perovskites were monitored by UV-visible absorption spectroscopy. The effects of polymer molecular weight, hydrophilicity, film thickness and molecular structure on perovskite encapsulations were investigated. The main results are as follows:

(1) PEG with a molecular weight of 6000 was used to prepare the encapsulation coatings. The relationship between the concentration and thickness of the pure polymer coating was monitored by an ellipsometer. Perovskites were encapsulated with coatings of different thicknesses, and the results showed that the film thickness would not influence the encapsulation effect of the polymer.

(2) PEG with molecular weight of 600, 6000 and 35000 have been used respectively. The results showed that a higher molecular weight of PEG demonstrates a better encapsulation effect, because the proportion of oxygen atoms which can form hydrogen bonds with water molecules is lower in high molecular weight PEG.

(3) The water contact angles of different polymer coatings were measured. The perovskites were encapsulated with those hydrophilic and hydrophobic polymer coatings. The results showed that the hydrophobic polymers demonstrated a significantly better encapsulation effect than that of the hydrophilic polymers.

(4) Comparing the encapsulation effects of several hydrophobic polymers, the results suggested that the encapsulation effect is more affected by the molecular structure of the polymer. A shorter molecular branch will lead to a smaller inter-molecular space, thus impart a denser polymer film and better encapsulation effect.

Key Words: Perovskite; Polymer; Encapsulation; Stability

目 录

第1章 绪论 1

1.1 引言 1

1.2 钙钛矿太阳能电池简介 1

1.3 影响钙钛矿太阳能电池稳定性的因素 3

1.3.1短期稳定性 3

1.3.2长期稳定性 4

1.4 增强钙钛矿太阳能电池稳定性的方法 5

1.4.1提高薄膜质量 5

1.4.2优化导电层和界面 5

1.4.3改善空穴传输层 6

1.4.4改善钙钛矿材料的组成 7

1.4.5封装 7

1.5 论文的选题依据和主要研究内容 8

1.5.1选题的目的及意义 8

1.5.2主要研究内容 8

第2章 实验部分 10

2.1 实验药品与设备 10

2.1.1实验药品 10

2.1.2实验设备 11

2.2 涂层的制备与表征 11

2.2.1钙钛矿层的制备 11

2.2.2钙钛矿太阳能电池的制备 11

2.2.3封装层的制备 12

2.2.4实验测试与表征 12

第3章 结果与讨论 14

3.1 膜厚对封装性能的影响 14

3.2 分子量对封装性能的影响 17

3.3 亲疏水性对封装性能的影响 19

3.4 分子结构对封装性能的影响 22

3.5 封装涂层在钙钛矿太阳能电池上的应用 24

第4章 总结与展望 26

4.1 实验总结 26

4.2 展望 26

参考文献 28

致　　谢 33

第1章 绪论

1.1 引言

化石能源的大量消耗和日益严峻的环境问题驱使人们不断开发新的能源，太阳能以其清洁、无污染、可再生等优点成为人们的研究重点。利用光伏效应，将光能直接转换为电能的太阳能电池，为利用太阳能提供了一条有效的途径^[1]。光伏发电主要利用太阳能电池将太阳所发射的光能转变为人们所需要的电能。如今，太阳能电池已经发展了三代，即晶硅太阳能电池、化合物太阳能电池和新型薄膜太阳能电池。在各类新型薄膜太阳能电池中，钙钛矿太阳能电池的发展尤为迅速^[2]。

1.2 钙钛矿太阳能电池简介