CsPbX₃ Nanocrystals Synthesis And Their Application In Solar Cells

CsPbX3 nanocrystals(NCs)have attracted substantial attentions due to their excellent photoelectric properties,including defect tolerance,tunable bandgap,and simple synthetic method etc.Solar cells based on CsPbX3 NCs as one of the promising applications have also developed rapidly recently.In this dissertation,we systematically studied the effect of synthesis controling of NCs on their photovoltaic performance,aiming to further improve device performance and stability.The specific contents of this paper are as followsFirst of all,the basic properties,synthesis strategies of CsPbX3 NCs and the development of perovskite NC solar cells are introduced.Secondly,synthesis of CsPbBr3 NCs and their application in solar cells are discribed.For the first time,FABr saturated methyl acetate solution was introduced to process CsPbBr3 NCs after their synthesis.The utilization of FABr not only facilitates ligand removal but also passivates the surface traps of NCs.After further device optimization,we obtained CsPbBr3 NC solar cells with an efficiency of 5.01%Moreover,postsynthetic surface treatment of CsPbI3 NCs via ZnI2 methyl acetate solution is studied.The CsPbI3 NCs film was treated with ZnI2 in methyl acetate for the first time.The study indicates that the function of ZnI2 is mainly to facilitate the removal of the long chain surface ligands,improving the coupling between NCs.As a result,a CsPbI3 NC solar cell with the photoelectric conversion efficiency(PCE)of 14.12%was achieved.In addition,ZnI2 treatment can improve the repeatability of high-efficiency devices.Lastly,efficient CsPbI3 NC solar cells with tunable Pb/I ratio and scalable yield based on ternary-precursors-synthesis is demonstrated.In this chapter,we systematically studied how Pb/I precursor ratio affect the synthesis of CsPbI3 NCs and their corresponding photovoltaic performance based on ternary-precursors synthesis.This strategy provides more flexibility on elemental adjustment compared to traditional binary-precursor-method.With the increased ratio of iodine precursor,the content of iodide ions and oleyl ammonium on the surface of NCs increase,resulting in enhanced surface passivation and superior optical properties.Meanwhile,this Pb/I precursor ratio exhibits huge effect on photovoltaic performance based on the synthesized CsPbI3 NCs.The CsPbI3 NCs synthesized with Pb/I precursor ratio of 1:3 exhibit the highest efficiency of 14.00%,benefiting from its appropriate ligand density and optimal surface passivation.In addition,ternary-precursor-method can increase the synthesis yield of NCs by 12 times compared to binary-precursor-method,which greatly reduce the cost of NCs synthesis and provide the possibility for large-scale synthesis of CsPbI3 NCs.To sum up,we studied the effects of synthetic conditions on CsPbBr3 NCs and their photovoltaic performance.Then the influence of ZnI2 on CsPbI3 NCs and their photovoltaic performance was investigated.Finally,the effect of Pb/I precursor ratio on the synthesis of CsPbI3 NCs was studied based on ternary-precursors-synthesis,and the obtained NCs were applied to solar cells.