Synthesis And Photovoltaic Application Of Nonfullerene Acceptor Materials Based On Two-Dimensional Benzodithionhene

The core component of organic solar cells is photovoltaic materials,non-fullerene acceptor materials have become the hotpoint research in the bulk heterojunction organic solar cells fields.A series of pulled electron unit-donated electron unit-pulled electron unit(A-D-A)type two-dimensional conjugated non-fullerene acceptors based on benzodithiophene core are synthesized and designed.The effects of the introducted of S atoms,the simultaneously introducted S and F atoms,and the introducted of different amount of F atom on the photovoltaic properties were investigated.1.We successfully designed and synthesized A-D-A type acceptors ITIC-T-S and ITIC-T-SF containing two-dimensional conjugated benzodithiophene(BDT)umits,and ITIC-T-S displays higher electron mobility,slightly wider optical band gap,and similar absorption.Compared with ITIC2(herein referred to as ITIC-T).ITIC-T-S shows a smaller crystal coherence length,weaker bimolecular recombination,and more efficient electron collection efficiency.Polymer solar cells based on PBDB-T-SF:ITIC-T-S achieves power conversion efficiency PCE of 11.6%with a fill factor FF of 66.8%and photoelectric conversion efficiency PCE of 11.6%,which is superior to PBDB-T-SF:ITIC-T devices(PCE=10.1%,FF=59.7%).Compared with ITIC-T-S,ITIC-T-SF acceptor introduces fluorine atoms on thenyl conjugated side chains,which have a wider optical gap and stronger light absorption,but the crystallinity is weaker.PBDB-T-SF and ITIC-T-SF depict the same donor unit BDT-SF and ITIC-T-SF,increases the crystallinity of,and it is beneficial to forming weaken the biomolecule recombination,the device based on PBDB-T-SF:ITIC-T-SF is up to PCE 12.1%with a FF of 68.6%.2.Three acceptor molecules ITIC-OF,ITIC-2F and ITIC-4F are synthesized by introducing different amount of F atoms:into the conjugated side chains of on the BDT unit.The results shows that three molecules have broad and strong absorption in the wavelength range of 500-800 nm.The more numbers of F atom is introduced into side chains on the conjugated core BDT,which is the larger the blue-shifted absorption spectra.The LUMO energy levels of all acceptors are-3.84～-3.86 eV.The decomposition temperature of the three molecules is about 340℃.The PM6:ITIC-2F-based device obtains the best efficiency of 10.81%,compared with the PM6:ITIC-OF-based(9.17%),and the PM6:ITIC-4F-based device(6.37%)。...