| Since Dye sensitized solar cells(DSSCs)were discovered by Gratzel and co-workers in 1991,they have caused sustainable attention owing to the cost-effective and flexible solar energy conversion.As the crucial structure material of DSSCs,the pure metal-free organic sensitizers are the mainstream of the research because of the advantages of feasible molecule,low material cost,easy preparation processes by comparison with metal ruthenium sensitizers.Base on dye photo-to-current conversion theory and the previous work,the dissertation designed three types of ten novel D-A-π-A carbazole dyes with N-substituted carbazole derivatives as donor,benzothiadiazole as auxiliary acceptor,thiophene or benzene as π-bridge and cyanoacetic acid or rhodanine acetic acid as acceptor.The reaction process and key step mechanism were analyzed.The spectral,electrochemical and photo-to-current conversion properties of these carbazole dyes were investigated systematicallyFour novel D-A-π-A N-butylcarbazole type sensitizing dyes were synthesized with N-butylcarbazole as donor,thiophene or benzene as π bridge,cyanoacetic acid or rhodanine acetic acid as acceptor and benzothiadiazole as auxiliary acceptor.N-butyl-c arbazo le reacted with NBS by electrophilic substitution to get 3-bromo-N-butyl-carbazole.4,7-dibromobenzothiadizole was introduced into N-butyl-carbazole donor by Suzuki coupling.Then,the intermediate aldehydes 1-9 and 1-10 were synthesized by the second Suzuki coupling with formyarylboronic acids.Finally,the intermediate aldehydes reacted with cyanoacetic acid or rhodanine acetic acid in the presence of piperidine by Knoevenagel condensation to get the target compounds ZXY-1-ZXY-4.Their optical absorption,photo-to-current conversion properties were analyzed.Though dyes ZXY-2 and ZXY-4 with rhodanine acetic acid acceptor have larger maximum absorption wavelength and molar extinction coefficient,DSSC based on them show the poor photoelectricity conversion efficiency(1.65%and 3.81%)because of their low IPCE value of 15%and 40%,Jsc value of 4.12 and 6.98 mA/cm2 respectively.Dye ZXY-1 with thiophene bridge and cyanoacetic acid acceptor exhibits superior optical absorption properties,which have higher IPCE value of 65%and Jsc value of 12.08 mA/cm2;dye ZXY-3 with benzene bridge and cyanoacetic acid acceptor has weaker absorption spectrum and lower molar extinction coefficient,but its Voc reaches 0.71V.Among the four N-butylcarbazole dyes,DSSC based on ZXY-3 with benzene bridge and cyanoacetic acid acceptor exhibits the highest efficient photo-electricity conversion efficiency(Jsc=10.99 mA/cm2,Voc=0.71V,FF=0.69,η=5.40%)。Four novel D-A-π-A N-phenylcarbazole type sensitizing dyes were synthesized with N-phenylcarbazole as donor,tlipophene or benzene as π bridge,cyanoacetic acid or rhodanine acetic acid as acceptor and benzothiadiazole as auxiliary acceptor.N-phenylcarbazole went through bromination with NBS,twice Suzuki coupling and final Knoevenagel condensation with cyanoacetic acid or rhodanine acetic acid by to get the target compounds ZXY-5-ZXY-8.Though dyes ZXY-6 and ZXY-8 with rhodanine acetic acid acceptor have larger maximum absorption wavelength and molar extinction coefficient,DSSC based on them show the poor photoelectricity conversion efficiency(0.82%and 2.77%)because of their low IPCE value of 7%and 36%,Jsc value of 2.29 mA/cm2 and 5.97 mA/cm2 respectively.DSSC based on ZXY-7 with benzene bridge and cyanoacetic acid acceptor shows superior IPCE and Voc,resulting in the highest efficient photo-electricity conversion efficiency(Jsc=9.14 mA/cm2,Voc=0.74V,FF=0.78,η=5.28%)。Two novel D-A-π-A N-octylcarbazole type sensitizing dyes were synthesized with N-octylcarbazole as donor,thiophene or benzene as π bridge,cyanoacetic acid as acceptor and benzothiadiazole as auxiliary acceptor.3-Bromo-N-octyl-carbazole was synthesized with NBS reaction followed by electrophilic substitution with bromooctane,and then went through twice Suzuki coupling and subsequent Knoevenagel condensation with cyanoacetic acid to get the target compounds ZXY-9-ZXY-10.DSSC based on ZXY-9 with thiophene bridge shows the red shift of UV spectra and higher Jsc,resulting in the highest efficient photo-electricity conversion efficiency(Jsc=13.69 mA/cm2,Voc=0.64V,FF=0.64,η=5.62%)。... |
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