Design And Synthesis Of Fluorinated P-type Conjugated Polymers For Application In All-Polymer Solar Cells

The power conversion efficiency(PCE)of all-polymer solar cells(all-PSCs)has rapidly increased to 8.27%in the past five years.The molecular structure,all-polymer blend morphology,device configuration and processing techniques are found to be critical in deciding the relevant device photovoltaic performance.In this thesis,a series of organic semiconducting conjugated polymer were designed and synthesized.We further investigate the correlation between molecular structure and all-PSCs performance.These results are summarized as follows:Firstly,we successfully designed and synthesized a series of BDT-Qx-T based polymers with introduction of different alkyl side chains in thienyl of benzo[1,2-b:4,5-b']dithiophene(BDT)structure and appended different numbers of fluorine atoms to quinoxaline(Qx)acceptor moiety.And the PCE of 5.35%was obtained for P2F-DO based single junction all-PSCs.Furthermore,the tandem all-PSCs were also fabricated with two identiacal P2F-DO based sub-cells,yielding a high PCE of 6.7%.This is the highest PCE reported for tandem all-PSCs.In the second part,with BDTDT-Qx-T polymer blockbone structure,polymer PDT-QxTEH were designed and synthesized by introduction of alkyl side chain on thiophen ?-bridge in polymer PDT-QxT.By systematically investigation,we found that the introduction of alkyl side chain in thiophen ?-bridge of donor polymer can efficiently improve the polymer solution processing,the polymer-polymer blend films and the properties of resultant devices.As a consequence,all-PSCs based on polymer PDT-QxTEH outperformed than those on PDT-QxT by 12.5%,which confirmed the beneficial role of alkyl side chain on the device performance.Finally,we successfully designed and synthesized two BDT-BT-T based polymers PT-BT and PT-BT2F as the donor polymers for all-PSCs.We found that fluorination can enhance charge transfer between donor and acceptor polymers,improve the hole mobilities and balance carriers transportation in all-polymer blends and finally improve the PCE of all-PSCs.Our work indicates that it is an effective method to meditate the optoelectronic properties of donor polymers and improve PCE of all-PSCs by reasonably tailoring the chemical structure of donor polymers.