| In recent years,organic-inorganic perovskite solar cells developed rapidly in the field of thin-film solar cells.After much effort,the power conversion efficiency（PCE）of PSCs has rapidly improved from 3.8% to 22.1% in the past few years,which is even higher than the improvement of the PCE observed for quantum dot sensitized solar cells and organic polymer solar cells.Perovskite solar cell includes electrode material,electron transport layer,perovskite absorbing layer,hole transport layer etc.Perovskite absorbing layer is really significant for the performance of the solar cells.The structure of the material is depend on the method of fabrication,and the performance of the material is depend on the structure of the material.So a simple and easy-to-control method is desired to fabricate high performance devices.In the past years,a lot of work has been devoted to studying the preparation method of novel solar cells,resulting in remarkable progress 。 This dissertation focuses on the fabrication of perovskite absorbing layer by a sequential multi-drop coating method.Some valuable results are listed as follows:（1）A simplified sequential multi-drop coating（SMDC）method is developed to stabilize the α-phase,control the growth of perovskite grains and regulate the remnant PbI2 for a pure FAPbI3 perovskite film under ambient conditions.The obtained film contains very large grains with preferred [111] orientation in the α-phase.The large grain size and high crystallinity dramatically reduce the grain boundary area and the associated charge recombination and contribute to a high short-circuit current density（JSC）and PCE of up to 23.86 mA cm-2 and 17.66%,respectively.In addition to improving the stability by reducing the grain boundary,this method also helps control residual PbI2 through a dropping and interdiffusion process.We then extend this method to the fabrication of a FA/MA mixed cation perovskite film.Finally,the highest PCE value of 19.3% is achieved.This provides a new effective approach towards high efficient FAPbI3 and FA/MA mixed cation perovskite film.（2）In the two-step deposition method,we change the second step into pure solution deposition.We studied the growth mechanism in the deposition process and annealing process.High crystallinity and micron-sized film are prepared by this situ cation displacement.By studying the property of the annealed and no-annealed perovskite film,the MA+ cation,which is deposited firstly,react with PbI2 film then formed the compact perovskite film.The FA+ cation,which is deposited after MA+ cation,and MA+ cation diffuse with a balanced cation exchange to form a graded distribution film.We prepared the micro-sized and uniform film.The highest PCE value of 20.44% is obtained.This result is instructive for the deep insight of the grown mechanism and the future designing of new method. |
