Study On Synthesis And Property Of The Dendritic Spirofluorene Hole Transport Materials

Choose the appropriate hole-transporting materials(HTMs) insert between perovskite and metal electrodes can improve battery performance, HTMs have been widely researched. As a successful HTM, Spiro-OMe TAD was commonly used in the area of perovskite solar cells(PSCs) because of its excellent electron transport properties and redox properties. But it still exists some shortcomings: the highly complex molecular architectures, extremely difficult to synthesize and its poor solubility in organic solvent. So it has important significance to develop HTMs with simple structure and better solubility for the development of PSCs. In this paper, two compounds 9,9’-([9,9’-bifluorene]-2,7-diyl)bis(N3,N3,N6,N6-tetrakis(4-methoxyph-nyl)-9H-carbazole-3,6-diamine)(Spiro-009) and 9,9’-([9,9’-bifluorene]-2-diyl)-(N3,N3,N6,N6-tetrakis(4-metho-xyphenyl)-9H-carbazole-3,6-diamine)(Spiro-014)were synthesized.The best synthesis method of N3,N3,N6,N6-tetrakis(4-methoxyphenyl)-9H-ca-rbazole-3,6-diamine)(CZ-OMEAD) was studied. The effects of reaction temperature, acid agents types, catalyst types on the reaction products yield was investigated. The results showed that the better reaction temperature was 55 ℃,n(DBr CZ-BOC): n(OMEAD): n(Pd2(dba)3): n((t-Bu)3P·BF4): n(sodium tert-butoxide)=1:2.25:0.02:0.04:2.5, reaction time was 2 h, and the yield of CZ-OMEAD was over 60.1%.The best synthesis method of Spiro-014 was studied. The effects of reaction temperature, reaction time, acid agents types, catalyst types on the reaction products yield was investigated. The results showed that the better reaction temperature was105 ℃, better reaction time was 24 h, n(CZ-OMEAD): n(2-bromo-9,9’-spriobifluore-ne): n(Pd2(dba)3): n((t-Bu)3P·BF4): n(potassium tert-butoxide)=1:1.2:0.04:0.08:2,and the yield of Spiro-014 was over 89.1%. Secondly, the purification process of product was studied. The obtained optimum conditions of recrystallization were m(methylbenzene): m(normal hexane): m(crude product) =10:10:1, the product was filtered at 70~75 ℃, and the purity of Spiro-014 was over 99.7%.The best synthesis method of Spiro-009 was studied. The effects of reaction temperature, reaction time, acid agents types, catalyst types on the reaction products yield was investigated. The results showed that the better reaction temperature was105℃, better reaction time was 24 h, n(CZ-OMEAD): n(2,7-Dibromo-9,9’-spriobi-fluorene): n(Pd2(dba)3): n((t-Bu)3P·BF4): n(potassium tert-butoxide)=2.25:1:0.03:0.06:3, and the yield of Spiro-009 was over 90.3%. Secondly, the purification process of product was studied. The obtained optimum conditions of recrystallization were m(ethylacetate): m(crude product)=10:1, crystallization temperature was 25~30 ℃, and the purity of Spiro-009 was over 99.2%.Their molecular structures were characterized by 1HNMR spectroscopy and LC-MS. Physical properties were examined by UV-Vis, electrochemical properties were characterized by Cyclic Voltammetry(CV), thermal stability was examined by thermogravimetric analysis. The results indicated that the obtained compounds have good thermal stablibilities and the appropriate HOMO trackenergy levels, which can be served as the hole transport materials in the PSCs.