Synthesis Of Donor-acceptor-donor Structure Hole Transport Materials And Their Applications In Perovskite Solar Cells

During the past decade,perovskite solar cells(PSCs)have achieved very rapid development and been one of the hottest research topics due to the merits of low cost,simple preparation,and high conversion efficiency.As the crucial part of PSCs,hole transport material(HTM)plays important role in achieving high efficiency.On the one hand,it can effectively enhance the charge separate and transport,on the other hand,it also has an important impact on the stability of the device.At present,Spiro-OMe TAD is the most widely used organic small molecule HTM.However,the complex synthesis route and purification process make Spiro-OMe TAD very expensive,limiting its possibilities for large-scale applications.Therefore,developing low-cost and efficient HTM to replace of Spiro-OMe TAD is highly desired.Under this background,in this thesis,a series of novel donor-acceptor-donor(D-A-D)structured small molecular HTMs with suitable energy levels,high stability,excellent hole mobility and conductivity are designed and synthesized,the physical and chemical properties and photovoltaic have been well characterized.The detailed research contents of the thesis mainly include the following aspects:1.By deliberately selecting fluorine substituted BTA as core building block,we synthesized two D-A-D type HTMs(2FBTA-1 and 2FBTA-2).The BTA decorated with one alkyl chain,which can improve the HTMs’ hydrophobicity and solubility in organic solvent,making it solution processable.Applied in mesoporous structured PSC,HTM 2FBTA-2 obtained a PCE of 17.94% that comparable with Spiro-OMe TAD,and good stability in ambient condition.2.We designed the molecules BDD-1 and BDD-2 with long alkyl chains substituted BDD unit.The alkyl chain can improve the HTMs hydrophobicity and solubility in organic solvent,making it solution processable.We explored the different effect with the introduction of different conjugated length substituted group on the properties of the PSCs.Applied in mesoporous with dopant free,BDD-1 and BDD-2 achieve the highest PCE of 18.12% and 17.39%,respectively.3.In this work,a new type of benzothiazole core unit based HTM was designed and synthesized which was named FBTZ.FBTZ has suitable energy level,excellent planeness and high hole mobility and conductivity.The passivation of perovskite interface can be achieved by fluorine atom modification.Applied in perovskite solar cell,the highest PCE of 18.9% can be achieved.