Star-shaped A-D-A compounds synthesized by different methods and used as donor or acceptor materials in organic photovoltaics

Star-shaped small molecule has lots of fascinating advantages compare with the linear small molecule. In this paper, two star-shaped small-molecules (S-TT and S-TT-R) with vinyl trithiophene with or without alkyl substituents as core, N-ethylrhodanine as terminal and withdrawing groups, vinyl as bridge group were synthesized by different synthetic routes. Both of the two materials demonstrate high thermal stability and broad absorption. Both S-TT and S-TT-R exhibit narrow bandgap (1.72 and 1.82 eV), low LUMO energy levels (− 3.92 eV) for S-TT and high HOMO energy levels (− 5.37 eV) for S-TT-R which could be applied as acceptor or donor materials for photovoltaics, respectively. Both of the two compounds were used as donor materials with PC₆₁BM acceptor and S-TT were used as acceptor material with P3HT donor.