Study On Synthesis And Photoelectric Performance Of Carbazole Dye Sensitizer

Dues to low cost,simple process and high photo-electricity conversion efficiency,Dye Sensitized Solar Cell?DSSC?has drawn more and more attention and study.Dye sensitizer is a critical component of DSSC,and absorbs sunlight to excite photoelectrons.In the Dissertation,we designed and synthesized eight carbazole dyes with carbazole and carbazole derivatives as donor,aromatic or aromatic heterocyclic as ?-bridge and cyanoacetic acid as acceptor.The molecular structures were characterized with NMR and MS.Their spectral properties,electrochemical properties and photovoltaic performance and the relationship between structure and properties are studied systematically.Three novel D-?-A carbazole dye sensitizers were synthesized with carbazole and derivatives as donor,4-phenyl-2-?thiophen-2-yl?thiazole as ? bridge,cyanoacetic acid as acceptor.Carbazole was substituted with4-?4-bromophenyl?-2-?thiophen-2-yl?thiazole to introduce ? bridge on the N atom,and then an aldehyde group was introduced on the thiophene ring by Vilsmeier reaction.Finally,the intermediate aldehyde reacted with cyanoacetic acid by Knoevenagel condensation to get compound LT-1.After the N-substituted 3-bromo-carbazoles was transformed to the corresponding boronic ester,it reacted with the4-?4-bromophenyl?-2-?thiophen-2-yl?thiazole through Suzuki coupling to the ? bridge.An aldehyde group was introduced on the thiophene ring by Vilsmeier reaction,andthe intermediate aldehyde reacted with cyanoacetic acid by Knoevenagel condensation to get compounds LT-2 and LT-3.The spectrum and photovoltaic performance were investigated systematically for LT-1^LT-3 and the relationship between structure and properties were studied.As the result that LT-2 with N-phenyl carbazole as donor,4-phenyl-2-?thiophen-2-yl?thiazole as ? bridge,cyanoacetic acid as acceptor exhibits optimum photo-electricity conversion efficiency 4.72%?Voc =0.66 V,Jsc= 10.01 mA/cm²,ff = 0.72?.Three carbazole dye sensitizers were synthesized with N-dimethylfluorene carbazole as donor,thiophene,furan or benzene as ? bridge,cyanoacetic acid as acceptor.Carbazole reacted with 2-bromo-dimethylfluorene to introduce the fluorene group on the N atom,and then was transformed to the bromide with NBS.The bromide reacted with?5-formylfuran-2-yl?boronic acid,?5-formylthiophen-2-yl?boronic acid and?4-formylphenyl?boronic acid respectively by Suzuki coupling to get aldehydes.Finally,the intermediate aldehydes reacted with cyanoacetic acid by Knoevenagel condensation to get compounds LT-4^LT-6.The spectrum and photovoltaic performance were investigated systematically for LT-4^LT-6 and the relationship between structure and properties were studied.As the result that LT-4 with N-dimethylfluoren carbazole as donor,thiophene ring as bridge,cyanoacetic acid as acceptor exhibits excellent conversion efficiency 4.46%?Jsc=7.48mA/cm²,Voc=0.69 V,ff= 0.86?.Two novel D-?-A carbazole dye sensitizers were synthesized with N-substituted carbazole as donor,2-phenyl-5-?thiophen-2-yl?-1,3,4-oxadiazole as ? bridge,cyanoacetic acid as acceptor.N-substituted 3-bromocarbazoles was transformed to the corresponding boronic ester,then reacted with the2-?4-bromophenyl?-5-?thiophen-2-yl?-1,3,4-oxadiazole through Suzuki coupling to introduced the ? bridge.After the introduction of an aldehyde group on the thiophene ring with Vilsmeier reaction,the intermediate aldehyde reacted with cyanoacetic acid by Knoevenagel condensation to get compounds LT-7 and LT-8.The spectrum and photovoltaic performance were investigated systematically for LT-7 and LT-8 and the relationship between structure and properties were studied.The result shows that LT-7with N-phenyl carbazole as donor,2-phenyl-5-?thiophen-2-yl?-1,3,4-oxadiazole as ?bridge,cyanoacetic acid as acceptor has better conversion efficiency 2.16%(Jsc=4.46mA·cm^-2,Voc=0.65 V,ff= 0.74).