Design,Synthesis,and Photovoltaic Application Study Of Nonfused Electron Acceptor Materials

The active layer is composed of a donor and an acceptor in organic solar cells.Active layer materials play an important role in improving power conversion efficiency of solar cells.Because of their simple synthesis,good stability and excellent solubility,nonfused electron acceptor materials have received a lot of attention.In this work,a series of nonfused acceptor materials with near-planar structures have been designed and synthesized.They were applied in the organic solar cells successfully.The specific research is divided into the following two parts.1.Design,synthesis,and photovoltaic application study of nonfused molecules.A series of nonfused molecules PPIC、PP4F、PTIC、PT4F were synthesized from 2,5-dibromo-1,4-benzenediol through seven step reactions.The reactions include alkylation,borylation,ring-closure,bromination,formylation,Suzuki coupling,and Knoevenagel condensation.Total yield of the four target compounds were 4%,4%,43%,and 55%,respectively.The four molecules have similar absorption range(400～800 nm),low LUMO energy levels(-3.78～3.9 eV),good thermal stability(T_d>290 ℃),and the near-planar structure.They can be used as acceptor materials in bulk heterojunction solar cells.The organic solar cells based on PBDB-T:PT4F showed a power conversion efficiency of 2.52%.2.Design,synthesis,and photovoltaic applications of nonfused polymers.Compounds 16 were synthesized from compound 13 through Knoevenagel condensation reaction.In order to improve the carrier transport and absorption spectra,a series of nonfused polymers P(PTIC-FT)and P(PTIC-FTT)were synthesized from compound 16 through Stille coupling reaction.Total yield of the two target polymers were 25%,and 50%,respectively.The two polymers have near-planar structure,good thermal stability(T_d>309 ℃),low LUMO energy levels(-3.95 eV,-3.83 eV),and wide film absorption range(350～800 nm).The organic solar cells based on the P(PTIC-FT)electron acceptor showed a power conversion efficiency of 8.9%...