Research On Performance Of Perovskite Solar Cells Based On Cryptand Doping

Nowadays,the demand for energy is increasing day by day,but the global reserves of fossil fuels can’t meet the current consumption rate,the development and utilization of new renewable clean energy is needed.Solar energy has the characteristics of huge amount,wide distribution,simple utilization and no pollution,and is a very good clean energy.Development of solar cells from the last century has been relatively mature,silicon solar cell has been industrialized for many years,but the silicon material price is higher,and subsequent recycling silicon-based solar cells is relatively cumbersome.Perovskite solar cells as the third generation of new type of thin-film solar cells,the perovskite light absorption layer be solution is good for the environment.Due to its low cost,adjustable band gap and low exciton binding energy,perovskite photovoltaic materials have attracted the attention and research of many scholars.After more than ten years of research and development,the laboratory preparation efficiency of perovskite solar cells has been closed to the theoretical limit,but the poor crystal quality of perovskite films has been one of the main reasons restricting the further improvement of device performance and stability.Excessive crystallization rate of perovskite film will lead to inconsistent grain size and pinholes on the surface of the film,resulting in more defects in the film.This increases the nonradiative recombination ratio of charges and reduces carrier utilization,and ultimately damage the performance and stability of battery devices.In this study,Cryptand has strong interaction with metal cation,in the preparation process of perovskite film Cryptand complexed with Pb I₂,forming into interphase,slowing down the crystallization rate of perovskite film,to obtain high crystal quality perovskite film.There are two parts to this job.In the first part,Cryptand molecules were introduced into 3D perovskite precursor solution to regulate 3D perovskite crystallization process.The experimental results show that Cryptand selectively interacts with Pb I₂,and Pb I₂ complexes with Cryptand to form into interphase and slow down the crystallization rate of perovskite in the process of solution spin coating.The crystal growth rate slows down,the grain size becomes more uniform and compact,and the surface of the film eliminates pinholes,and the crystal quality is improved.To improve the quality of perovskite crystal film density of defect mode,reduce the charge recombination center,restrain the radiative recombination of the charge,high crystal quality of perovskite films also strengthened interaction between the transport layer.After optimization,the power conversion efficiency of 3D perovskite solar cells increased from 19.5%to 21%,and the device stability was also improved.Compared with 3D perovskite materials,quasi-2D perovskite contains larger organic spacer cations.On the one hand,it can improve the stability of devices;On the other hand,blocking charge transmission reduces the performance of devices The second part is to improve the crystallization of quasi-2D perovskite by introducing Cryptand molecules into the precursor solution.The results show that the crystal quality of quasi 2D perovskite is improved by introducing Cryptand molecules,the defect density in the perovskite film is reduced,the charge utilization ratio is improved,the cracks and pinholes on the film surface are reduced,and the direct contact between the quasi-2D perovskite layer and the transport layer is improved.After optimization,the short-circuit current of the quasi-2D perovskite solar cell is increased from 9.76 m A/cm² to13.02 m A/cm²,the power conversion efficiency is greatly increased from 6.55%to10.26%,and the stability has also increased.To sum up,this thesis will point to Cryptand doped perovskite precursor solution in regulating the crystallization behavior of perovskite,on the one hand,it optimized the 3D perovskite crystal size and thin film surface morphology,on the other hand,it raised the quasi 2D perovskite membrane current density,to improve the performance of perovskite solar cells provide a new choice.