Synthesis Of CH₃NH₃PbI₃ And Its Application In Mesoporous Perovskite Solar Cells

With the rapid development of economy,the consumption of non-renewable energy such as coal,oil,natural gas and other non-renewable energy has been accelerated.And the sun is not only the main energy supply for the survival of life on earth to provide a steady stream of human energy,but also the manufacturers of a lot of other clean energy.Therefore,the development of solar energy resources is the current research focus of new energy.CH₃NH₃PbI₃ material as an optical absorption layer has a very wide application prospect in solar cell due to its proper bandwidth,high absorption coefficient,excellent carrier transport performance and high defect tolerance.Herein,in this paper,we use the CH₃NH₃PbI₃ thin films of high quality prepared by one-step method and two-step method to explore the ideal preparation process,in order to improve the coverage of the perovskite film and increase the perovskite grain size,and further explore the photovoltaic properties of the mesoporous structure of perovskite solar cell.The main experimental results are as follows:1.Preparation techniques and research on CH₃NH₃I and CH₃NH₃PbI₃.CH₃NH₃I powder with good crystallinity and growth along the specific direction was prepared by solution method,which provided the basis for the preparation of high quality CH₃NH₃PbI₃ thin film.Then,CH₃NH₃PbI₃ thin film with different morphologies were prepared by one step method and two step method,we can know that the CH₃NH₃PbI₃ thin film prepared by the modified two step method can be used to cover the surface of mesoporous TiO2 thin film,and the grain size is more uniform,indicating that high quality CH₃NH₃PbI₃ thin film can be prepared by this modified two step method.2.Photovoltaic properties of perovskite solar cells with mesoporous structure.In this chapter,we mainly study and optimize the preparation process of each layer of thin film solar cells.Firstly,CH₃NH₃PbI₃ thin film was prepared by one step method and two step method,and then assembled into solar cells.The highest efficiency of the solar cell was obtained by the modified two step method,which was 6.35%（measured under standard AM1.5G test conditions）,And then explores the hole transport layer of spin coating process and atmosphere processing,impact on the gold electrode,the mesoporous layer thickness and treated with TiCl4 solution and perovskite layer thickness on the characteristics of the photovoltaic cells,by the whole process optimization,the efficiency of the inorganic-organic hybrid perovskite solar cells was achieved to 12.83%.It exhibited a high short circuit current density of 17.18 mA cm-2,an open circuit voltage of 1.07 V and a FF of 0.70.3.Application of solvent engineering in mesoporous structure perovskite solar cells.In order to improve the coverage of the perovskite film and increase the grain size of the perovskite,herein,we report that flat,uniform thin films of this material can be deposited by a two-step,solvent-induced,fast crystallization method involving spin-coating of a N,N-dimethylformamide（DMF）solution of PbI2 followed immediately by exposure to chlorobenzene to induce crystallization.Analysis of the devices and films revealed that the solution processing technique has changed the kinetics of nucleation and crystal growth of the perovskite during the spin coating producing very uniform perovskite thin films.Using this technique for the fabrication of solid-state mesoscopic solar cells greatly increases the reproducibility of their performance and allows us to achieve a power conversion efficiency of 12.08%.Here,we use a strong coordinative solvent of dimethyl sulfoxide（DMSO）instead of commonly used DMF which is easy to crystallization.And explore the effects of different proportions of DMF-DMSO treatment on the morphology and photoelectric properties of solar cells.The results show that when the volume ratio of DMF:DMSO is 4:1,highly efficient and reproducible mesoporous structured perovskite solar cells were obtained with the best efficiency of 13.93%.