The Synthesis And Characterization Of Polythiophene Derivatives As Donor For Polymer Solar Cells

Solar energy is inexhaustible and polymer solar cells have attracted much attention due to their properties of easy fabrication,flexible modules and making large area through solution processing.In recent few years,non-fullerene polymer solar cells,consisting of polymers as the donors and the non-fullerene materials as the acceptors,have been developed rapidly,and the highest power conversion efficiencies of them exceed those of fullerene-based ones.The highest power conversion efficiency has been over 14%.In fact,non-fullerene polymer solar cells have specific requirements for polymer donors.In this work,we synthesized a series of wide-bandgap polymer donor materials taking their absorption spectrum and matched levels into account.The main results are as follows:1.A new polythiophene derivative PBSBT-2F with alkylthio side chains and fluorine atoms was designed and synthesized.The polymer has a strong absorption at 400–680 nm,which is complementary with that of the small molecule acceptor ITIC.The PSCs based on PBSBT-2F:ITIC achieved a PCE of 6.7%with a Voc of 0.75 V,a Jsc of 13.5 mA·cm^-2and a FF of 66.6%under the illumination of AM 1.5 G,100 mW cm^-2.2.A new WBG polymer?PBDT-2SBT?based on alkylthienyl-substituted benzodithiophene was designed and synthesized for application as donor material in non-fullerene PSCs.The polymer exhibited a wide bandgap of 1.84 eV and a deep HOMO energy level of-5.25 eV.The PSCs based on PBDT-2SBT:O-IDTBR showed a PCE of4.7%with a Voc of 0.96 V,Jsc of 8.6 mA cm^-2,and FF of 56.5%.3.A new polymer PBBF based on benzodithiophene units was designed and synthesized for application as donor material in non-fullerene PSCs.The polymer exhibited a strong absorption in the range of 300-605 nm with a bandgap of 2.05 eV.It also possessed a deeper HOMO energy level of-5.52 eV and a higher hole mobility of7.3×10^-4cm² V^-1s^-1.The PSCs based on PBBF:IDIC showed a higher PCE of 8.5%without post-processing with a Voc of 0.95 V,Jsc of 15.3 mA cm^-2,and FF of 58.8%under the illumination of AM 1.5 G,100 mW cm^-2.