【作者】 彭博；

【导师】 严铮洸；

【作者基本信息】 北京工业大学 ， 物理学， 2020， 硕士

【摘要】 有机-无机卤化物钙钛矿材料因其在太阳能电池领域的应用潜能,迅速跻身材料研究前沿。影响光电器件性能的不可忽视的因素之一是作为光吸收层的钙钛矿薄膜的质量。目前制备钙钛矿薄膜主要方法之一是一步溶液法,该方法有着操作简单,成本低廉的优点,并且可在大气环境下进行,但由于溶液向薄膜的转变过程迅速,制备的薄膜质量往往难以控制。为了探究大气环境制膜方法及改善最终制得的薄膜质量和器件性能,我们通过研究钙钛矿薄膜的制膜前后及薄膜生长过程,研究溶剂氛围热处理手段并优化了这一方法,在典型的MAPb I₃和Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃体系中制备出了高质量,形貌好,晶粒尺寸达到微米级的有机钙钛矿薄膜,以XRD、SEM、UV-Vis、PL等技术表征了薄膜的相态、结构、形貌、光学性能,结合Lamer生长模型分析了晶体生长过程。在此基础上,制备了太阳能电池器件,所得太阳能电池器件性能与对照样相比明显提高。具体结果如下:1.在钙钛矿薄膜制备,以及相关器件制备及测试方面,我们开展的工作包括:研究了甲胺气体解离单晶制膜法,以及被广泛使用的添加反溶剂制备钙钛矿薄膜的方法,研究发现掌握反溶剂的滴加时间是提高薄膜质量的必要条件;在使用溶液法制备钙钛矿薄膜过程中,调整前驱体中的反应物的投料比可以一定程度地优化薄膜质量,初期制备钙钛矿平面型太阳能电池时,实验发现通过氧化空穴层,有利于提高太阳能电池器件的性能,其中主要参数短路电流密度由10.14 m A/cm²提高到16.51 m A/cm²。2.采用典型体系MAPb I₃,开发了溶剂氛围热处理方法。优化了热处理的时间,并使用低剂量DMSO溶剂进行循环处理,延长薄膜的再生长时间,得到了晶粒尺寸增大15倍的薄膜,晶粒平均尺寸由0.189?m增加到3.02?m,并且制备的钙钛矿太阳能电池光电转化率由11.9%提高到14.25%。并研究了不同的溶剂（DMF、DMSO、NMP）氛围对钙钛矿薄膜的作用,研究发现,有机溶剂对于薄膜晶粒长大均有类似的作用,薄膜晶粒平均尺寸相较于传统热处理方法制备的薄膜有一定程度增大,这一过程可以用Ostwald熟化理论解释。3.制备了混合阳离子钙钛矿薄膜并进行了溶剂气氛热处理,并且研究了传统热退火和DMF、DMSO、NMP三种有机溶剂氛围退火对于钙钛矿薄膜的作用差别,实验表明使用DMSO溶剂进行退火能明显增加经理尺寸,且该方法制备的薄膜的稳态荧光光谱强度相比传统方法制备的薄膜强,经过时间分辨光致发光谱计算,载流子寿命由321.6ns增加到620.8ns说明了该方法制备的薄膜的缺陷减少,质量提升。在大气条件下制备了高填充因子0.748、光电转换效率达17.25%的混合型阳离子钙钛矿太阳能电池并进行了电学性能测试分析薄膜中的缺陷和载流子传输过程。综上所述,本文中,针对钙钛矿薄膜质量在大气中制备存在的问题,我们对有机钙钛矿薄膜的溶剂蒸汽热处理制备方法开展了研究,通过对薄膜生长前后的过程进行调控,得到了制备大尺寸,高结晶度薄膜的方法,研究结果对大气条件下低成本高效率制备各种有机钙钛矿薄膜提供了理论依据,有望对钙钛矿太阳能电池的高效制备提供支持。更多还原

【Abstract】 The organic-inorganic halide perovskite materials have been rapidly promoted to the frontier of material research due to their potential applications in the field of solar cells.One of the important factors affecting the performance of optoelectronic devices is the quality of perovskite film as a light absorption layer.Meanwhile,the solution method is one of the most important methods of preparing perovskite film.This method is simple and low cost,and can be carried out in atmospheric environment.However,due to the rapid transformation process from solution to film,the quality of the prepared film is often difficult to control.To explore the method for preparing perovskite film in atmospheric environment and improve the quality of thin film and device performance,we studied the perovskite thin film growth process,besides,the solvent annealing treatment was used and this method has been optimized,in a typical MAPb I₃ and Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ system.We have achieved perovskite films with high quality,good morphology,large grain size which could reach micron grade.XRD,SEM,UV-Vis,PL technology was used to represent the phase,structure,morphology and optical properties of thin films.The crystal growth process was analyzed by Lamer growth model.On this basis,the solar cell device was prepared and the performance of the solar cell device has been obviously improved compared with the conventional one.The specific results are as follows:1.In terms of the preparation of perovskite film and solar device,our work includes:studying the method of methylamine gas slicing single crystal forming film,and the widely used method of adding anti-solvent to prepare perovskite film.It is found that mastering the dropping time of anti-solvent is a necessary condition for improving the film quality.In use of perovskite thin film prepared by the solution process,adjusting the weight ratio of reactant in the precursor could optimize the quality of thin film.During the process of preparing perovskite planar solar device,it was found that by oxidize the hole transport layer,the performance of the solar cell device could be improved,in which the main parameters of short circuit current density increased from10.14 m A/cm²to 16.51 m A/cm².2.The typical MAPb I₃ was used to develop the solvent atmosphere annealing method.The solvent annealing treatment was optimized and low-dose DMSO solvent was used for cycling treatment to prolong the film’s recrystallization time.The film with grain size increased 15 times was obtained.The average grain size increased from 0.189micron to 3.02 micron and the photoelectric conversion rate of the perovskite solar cell was increased from 11.9%to 14.25%.The effects of different solvents（DMF,DMSO and NMP）on perovskite films were also studied.It was found that organic solvents had similar effects on the film,and the average size of film grains increased to a certain extent comparing with the film prepared by traditional heat treatment.This process can be explained by Ostwald maturation theory.3.We prepared mixed cationic perovskite films and treated them with solvent annealing method,three kinds of organic solvent（DMF,DMSO,NMP）was used.The experiments have shown that using DMSO solvent annealing could significantly increase the grain size of the film.The steady-state fluorescence spectrum intensity of the films treated by solvent annealing method increased comparing with the films treated by traditional annealing method.The result of time-resolved photoluminescence spectrum show that carrier life expectancy of the films increased from 321.6 ns to 620.8ns illustrates the method of preparing thin film could improve the film quality.The mixed cationic perovskite solar cells with a high filling factor of 0.748 and a photoelectric conversion efficiency of 17.25%were prepared under atmospheric conditions.The defects and carrier transport process in the thin film were analyzed by electrical performance test.In conclusion,in view of improving the perovskite film quality in the atmosphere,we explored solvent vapor annealing treatment.By researching the process of thin film growth before and after regulation,the film with large size,high crystallinity was achieved.The results provide a theoretical basis for the low cost and high efficiency preparation of various organic perovskite films under atmospheric conditions,which is expected to provide support for the high efficiency preparation of perovskite solar cells.更多还原