Synthesis And Characterization Of Alcohol Soluble Fluorenyl Conjugated Polymers Containing Pyrenyl Or Fullerenyl As Side Chains

Nowdays,the energy crisis and environmental pollution have become major challenges,so it is imperative to develop green energy.Among them,the polymer solar cell（PSC）is one of the best green energy technology with great application potential due to its unique advantages.As an important part of the polymer solar cell,the cathode modified layer（electron transport layer,ETL）plays a key role in reducing the contact barrier between the active layer and the electrode,facilitating the selective collection and effective transport of carriers.The research content of this dissertation mainly includes two aspects:firstly,the side chain of amine-functionalized conjugated polymers was optimized,and a series of novel alcohol-soluble conjugated polymers（ACPs）containing fullerenyl or pyrenyl branches were designed and synthesized,and applied to the cathode interface modification layer of the inverted PSC（i-PSC）;the second is the application of the alcohol-soluble conjugated polymers in the polymer photodetectors as an interface modification layer,Explore the effect and mechanism of improving photovoltaic performance and light detection capability.In chapter 2,a series of alcohol-soluble conjugated polymers containing different content pyrenyl branches were synthesized by the Suzuki coupling polymerization in the presence of Pd（PPh₃）₄,using2,7-dibromo-9,9-bis（3’-N,N-dimethylamino-propyl）fluorene（FN）,2,7-di（4,4,5,5-tetracarboxylic）-1,3,2-dioxaborane-2-yl)-9,9-bis（3’-N,N-dimethylamino-propyl）fluorine（FNB）,2,7-dibromo-9-（10-（indol-1-yl）decylalkyl）-9H-carbazole（CzPy）as copolymerization comonomers,named as PFN-CzPy15,PFN-CzPy25,PFN-CzPy35.The corresponding quaternary ammonium conjugated polyelectrolytes were obtained by2-bromoethanol,named as PFN-CzPy15+,PFN-CzPy25+,PFN-CzPy35+.The HOMO energy levels(E_HOMO,-5.66^-5.63 eV)and LUMO level(E_LUMO,-2.80^-2.74 eV)of the polymers were calculated from the absorption spectra and cyclic voltammetry（CV）data.The materials were used as the ETL of i-PSCs with devices structure of ITO/ETL/P3HT:PC₆₁BM/MoO₃/Ag.The device with PFN-CzPy25+has the best performance,with a power conversion efficiency（PCE）of 3.22%,an open circuit voltage(V_oc)of 0.63 V,a short circuit(J_sc)of 7.91 mA/cm²,and a fill factor（FF）of 64.5%.Under the same conditions,the performance was better than the device with ZnO as ETL(PCE of 2.50%,J_sc of 7.40mA/cm²,V_oc of 0.58 V,FF of 59.95%)and the device with PFN as ETL(PCE of 2.71%,J_sc of 7.48mA/cm²,V_oc of 0.63 V,FF of 57.83%).In the third chapter,the graphenes were dispersed in methanol solution with the help of PFN-CzPy5,PFN-CzPy15 and PFN-CzPy25.The homogeneous solution was prepared.The graphene composite film was studied for influence on the surface morphology of ITO,and it was used as a cathode modification layer for i-PSC devices in which the P3HT/PC₆₁BM as active layer,and the device performance of the PFN-CzPy15-doped graphene was optimized.PCE reached 3.18%,V_oc was 0.63 V,J_sc was 8.28 mA/cm²,FF was 61.09%,it was a significant improvement compared with the device performance of PFN-CzPy15(PCE=2.41%,V_oc=0.60 V,J_sc=7.23 mA/cm²,FF=55.75%).In the chapter 4,we characterized the extremely narrow band gap polymer PDTTZ-TT and found that the polymer has good absorption in the range of 300-1300 nm.Combined with the absorption and CV data,the calculated E_HOMO is-4.96 eV,and the E_LUMO is-3.98 eV.The organic photodetector devices with PDTTZ-TT/PCBM as active layer were optimized.It was found that using alcohol-soluble conjugated polymer PFN as the cathode modification layer make the dark current of the inverted device（ITO/PFN/PDTTZ-TT:PC71BM（1:1.5）/MoO₃/Ag）significantly reduced,achieving optimal performance with PCE of 1.42%,V_oc of 0.44 V,J_sc of 5.31 A/cm²,FF of 60.8%,and the detectivity reaches 3.8×10¹²–7.3×10¹² Jones in the range from 350 nm to 1160 nm at zero bias,and the overall performance can be comparable to or even better than that of the silicon-based photodetector.In the fifth chapter,the chain type 2-hexyl decyl alkyl（HD）is used to optimize the side chain of the TZ-based narrow band gap conjugated polymer,and the two narrow band gap conjugated polymer named PHDTZ-T and PHDTZ-TT were synthesized,and they have good solubility and large molecular weights,the processing performance is improved.The HOMO and LUMO levels of PHDTZ-T and PHDTZ-TT were-5.01,-4.05 eV and-5.07 and-4.09 eV respectively,calculated by combining the absorption spectrum and electrochemical dataIn sixth chapter,the fullerene dibromide monomer CzFBr was synthetized by the addition reaction of organic azide and fullerene(C₆₀),and a series of conjugated polymers containing different content fullerenyl branches were synthesized with FN,FNB and CzFBr by the Suzuki coupling polymerization.Unfortunately,the polymers have a poor solution processing property,can not be applied in the PSC devices.