【作者】 张强；

【导师】 郭文滨；

【作者基本信息】 吉林大学 ， 工程硕士（专业学位）， 2023， 硕士

【摘要】 近年来,钙钛矿太阳能电池（Perovskite solar cells,PSCs）因其良好的光伏性能成为了研究焦点。PSCs的能量转换效率（Power conversion efficiency,PCE）从3.8%提高到25.7%,这是一个里程碑式的进步。钙钛矿膜的制备工艺以基于溶液法的薄膜沉积技术为主,包括一步法和两步法。但是基于反溶剂的一步法制备出的钙钛矿薄膜形貌不易控制,薄膜覆盖率低,表面和晶界处存在大量缺陷。而两步法制备钙钛矿薄膜可以更好的控制钙钛矿薄膜形貌,首先制备碘化铅（Pb I₂）薄膜,然后在其上方旋涂有机卤化物溶液,有机卤化物溶液在Pb I₂中扩散并发生反应形成钙钛矿。其中,Pb I₂薄膜的形貌对这种扩散起决定性的作用。为了解决这些问题,本论文在Pb I₂前驱体溶液中引入添加剂,通过调控Pb I₂薄膜形貌,减少薄膜缺陷,促进载流子传输,得到高性能的钙钛矿太阳能电池。具体研究内容如下:一、在两步法制备钙钛矿薄膜的过程中,Pb I₂和有机卤化物需要充分反应以形成钙钛矿,而这个反应的效率在很大程度上取决于Pb I₂薄膜的形貌。如果Pb I₂薄膜过于致密,将不利于有机卤化物在平面异质结中的扩散,从而降低反应效率。为了解决这个问题,我们引入了丙酮作为Pb I₂的薄膜形貌调节剂。丙酮的加入减弱了DMSO与Pb I₂的相互作用,从而形成了形貌更为合适的Pb I₂薄膜。Pb I₂可以更有效地与有机卤化物反应,从而转化为高质量的钙钛矿薄膜。通过这种方法制备出的FA_1-xMA_xPb I₃钙钛矿薄膜具有较低的缺陷密度,其中,含有1%丙酮的PSCs可以提供22.07%的PCE,这说明优化Pb I₂薄膜形貌可以大大提高电池的性能。这个工作对于实现高效率、低成本的太阳能电池具有重要意义。二、添加剂可以调控Pb I₂薄膜形貌,进而影响钙钛矿薄膜质量,我们提出了一种添加剂策略并应用于两步法制备钙钛矿薄膜,即在Pb I₂前驱体溶液添加乙腈（Acetonitrile,ACN）调控Pb I₂薄膜形貌,由于ACN的沸点低,挥发速度大于二甲基亚砜（Dimethyl sulfoxide,DMSO）和N,N-二甲基甲酰胺（N,N-Dimethylformamide,DMF）,在Pb I₂薄膜的退火过程中会优先挥发,留下孔隙,有利于有机卤化物的扩散,提升了Pb I₂向钙钛矿的转化率,从而获得高质量的钙钛矿薄膜,提高钙钛矿薄膜的吸光能力,降低了缺陷密度。与不添加ACN的PSCs相比,1.2%ACN的PSCs的PCE从19.77%提升至21.79%。这种简单易操作的方法,为PSCs的商业化提供一条新思路。更多还原

【Abstract】 In recent years,perovskite solar cells（PSCs）have become a research focus due to their excellent photovoltaic performance.The power conversion efficiency（PCE）of PSCs has increased from 3.8%to 25.7%,which is a milestone progress.The preparation process of perovskite films is mainly based on solution-based film deposition techniques,including one-step and two-step methods.However,it is difficult to control the morphology of the perovskite films prepared by the one-step method involving anti-solvent,these films have low film coverage and contain a large number of defects at the surface and grain boundaries.The two-step method allows better control of the morphology of perovskite films.Firstly,lead iodide（Pb I₂）film is prepared,and then the organic halide solution is spin-coated on it.The organic halide solution diffuses in film and reacts with Pb I₂ to form perovskite.The morphology of the Pb I₂ film plays a decisive role in such diffusion.To solve these issues,this paper introduces additives into the Pb I₂ precursor solution to control the morphology of the Pb I₂ film,thus reducing film defects,promoting carrier transport and obtaining high-performance perovskite solar cells.The research contents are as follows:1.In the process of preparing perovskite films by the two-step method,Pb I₂ and organic halides need to react sufficiently to form perovskite,and the reaction efficiency largely depends on the morphology of the Pb I₂ film.If the Pb I₂ film is too dense,it will hinder the diffusion of organic halides in the planar heterojunction,thereby reducing the reaction efficiency.To solve this problem,we introduce acetone as a morphology regulator for the Pb I₂ film.The addition of acetone weakens the interaction between DMSO and Pb I₂,thereby forming a more suitable Pb I₂ film morphology.Pb I₂ can react with organic halides more effectively,resulting in the conversion to high quality perovskite films.The FA_1-xMA_xPb I₃ perovskite film prepared by this method has lower defect density.PSCs containing 1%acetone can provide a PCE of 22.07%,which indicates that optimizing the morphology of the Pb I₂ film can greatly improve the device performance.This work is of great significance for achieving efficient and low-cost solar cells.2.Additives can modulate the morphology of Pb I₂ films,which in turn affects the quality of the perovskite films,we propose an additive strategy and apply it to the two-step method for preparing perovskite films.Specifically,we add acetonitrile（ACN）to the Pb I₂ precursor solution to control its morphology.Due to the low boiling point of ACN,it evaporates faster than dimethyl sulfoxide（DMSO）and N,N-dimethylformamide（DMF）during the annealing process of the Pb I₂ film,leaving pores which facilitate the diffusion of organic halides and improve the conversion efficiency of Pb I₂ to perovskite.Therefore,the high-quality perovskite films with enhanced light absorption and reduced defect density are obtained.Compared with PSCs without ACN,PSCs with 1.2%ACN showed a significant improvement in PCE from 19.77%to21.79%.This simple and easy-to-use method provides a new approach for the commercialization of PSCs.更多还原