制备高质量薄膜提升有机-无机杂化钙钛矿太阳电池光电性能

【作者】 杨艳；

【导师】 赵婉亘；

【作者基本信息】 陕西师范大学 ， 工程硕士（专业学位）， 2022， 硕士

【摘要】 钙钛矿半导体材料因兼具材料性质（吸光系数高、带隙可调、缺陷态密度低、激子结合能小以及载流子扩散长度长）和制备工艺（可溶液法低成本制备）的特点,受到众多科研学者的青睐,在新能源科技创新领域占据重要地位。仅十余年的发展,有机-无机杂化钙钛矿太阳电池光电转换效率已达到25.7%,但远低于其S-Q极限最大理论效率（>30%）。这是由于多晶钙钛矿薄膜体相与界面处的缺陷堆积引起载流子非辐射复合从而限制其性能提升,而制备高质量光活性层是解决此问题的有效途径。本论文通过表面终端设计,延缓结晶速率以及埋底界面改性的方法制备高质量钙钛矿薄膜。钝化缺陷,改善载流子输运提升器件光伏性能和稳定性。以下是本论文主要研究内容:（1）合理的终端设计有利于提升光电性能和运行稳定性。此工作选择硫氰酸胍（GASCN）,利用其强键合能力与[Pb I₆]^4-八面体增加的氢键相互作用修饰甲胺基钙钛矿薄膜的表面终端。首先测试多种极性不同的溶剂,考虑其对薄膜的冲刷和极性侵蚀,研究其对钙钛矿活性层的影响。其次由于界面处缺陷密度较大的特点,利用GA⁺与钙钛矿表面的强化学键合,在热退火后形成表面基质,强表面相互作用限制阴离子（I^-）的迁移,钝化薄膜表界面缺陷,抑制器件的迟滞效应。此外,表面基质阻断了大气中水分和氧气的入侵,从而提高了电池器件的长期稳定性。（2）引入2-乙基己酸铅熔融盐延缓钙钛矿结晶过程提升薄膜质量。通过原位紫外吸收测试揭示了由熔融盐添加剂引导的钙钛矿的详细结晶过程。观测薄膜形成过程,可以明确地认识到两个不同的晶体生长阶段,熔融盐添加剂显著延长了第一阶段的时间,并诱导了一个缓慢的相变路径。大量的实验结果表明熔融盐的引入抑制结晶动力学,提高钙钛矿薄膜的质量,调控能级分布,降低缺陷密度,改善光电性能。（3）基于合成的萘酰亚胺衍生物自组装单分子层修饰空白FTO导电玻璃,自组装单分子层的缺电子特性有效提高基底界面对电荷的提取效率,并且为钙钛矿前驱体的沉积提供更加光滑平整的基底界面,使得钙钛矿薄膜沉积质量提升,简化流程制备无电子传输层n-i-p型钙钛矿太阳电池。通过强分子间键合作用优化表界面光电性能,使得太阳电池光电转换效率从14.05%提升至16.05%。更多还原

【Abstract】 Perovskite materials are popular among researchers because of their material properties（high light absorption coefficient,adjustable band gap,low defect density,low exciton binding energy and long carrier diffusion length）and preparation process（low-cost preparation by solution method）,which occupy an important position in the field of new energy science and technology innovation.With the development of more than ten years,the power conversion efficiency of organic-inorganic hybrid perovskite solar cells has reached 25.7%,which is far below its S–Q limit maximum theoretical efficiency（>30%）.The defect accumulation at the bulk and interface of perovskite films leads to non-radiative recombination of carriers,which limits its performance improvement.The preparation of high-quality photoactive layer is an effective way to solve this problem.In this paper,high quality perovskite films were prepared by surface terminal design,delaying crystallization rate and bottom-buried interface modification to passivate defects,improve carrier transport and photovoltaic performance and stability of devices.The main research contents are following:（1）Guanidinium thiocyanate（GASCN）was selected to modify the surface terminations of methylamine lead iodide perovskite films by taking advantage of its strong bonding capacity and increased hydrogen-bond interactions with the[Pb I₆]^4-octahedron.Multiple solvents with varied polarity were tested to examine their effects on the perovskite layer in consideration of their scouring or polar erosion effect.The surface matrix is formed after thermal annealing due to the strong chemical bonding between GA⁺and the perovskite surface.The strong surface bonding immobilizes the anion（I^-）and reduces its migration,suppressing the hysteresis behavior of assembled device.As well,the surface matrix blocks invasion of moisture and oxygen from the atmosphere and thus improves the long-term stability of assembled devices.（2）The detailed crystallization process of perovskite guided by a molten salt additive is revealed by in-situ UV absorption.Two distinct stages of crystal growth can be clearly recognized through the film formation process,and the molten salt additive significantly lengthening the time of the first stage and inducing a slow phase transition path,which may be responsible for impeding the crystallization kinetics.After crystallization,functional groups interact with perovskite to change the physical and chemical properties of the film.According to a series of experimental results and calculations,the introduction of molten salt inhibits crystallization kinetics,improves the quality of perovskite films,reduces defect density and improves photoelectric properties.（3）The synthesized naphthalimide derivative self-assembled monolayer modified blank FTO conductive glass to improve charge extraction on the substrate interface without parasitic absorption,and provide a smoother and flat substrate interface for the deposition of perovskite precursor,thus improving the deposition quality of perovskite film.N-i-p perovskite solar cells without electron transport layer were prepared by simplified process.The power conversion efficiency of solar cells was increased from 14.05% to 16.05% by optimizing the interface photoelectric performance with strong intermolecular bond cooperation更多还原