Design,Synthesis And Application Of Electron Transport Materials Based On Naphthalene Diimides And Subphthalocyanines

Solar energy is the clean and renewable energy source.Organic photovoltaic cells based on photovoltaic effect are promising solutions for energy crisis.In this study,naphthalimide derivatives and subphthalocyanine derivatives were synthesized and used as electron transporting materials in the bulk heterojunction solar cells.1)Different semiperfluoroalkyl groups were introduced at the N-terminus of the naphthalimide,and six donor-acceptor type corresponding polymers were synthesized by a multi-step synthesis.Their optical properties,electrochemical properties,thermal stability,contact angle,self-assembly properties were investigated.The results show that the suitable semi-perfluoroalkyl group is the key to ensure high solubility of such soluble polymers.As the electron donating ability of the donor units increases,the absorption of these acceptor materials red-shifts.Their LUMO energy levels as low as-3.90 e V,indicating their strong electron accepting capacity;the decomposition temperature of these polymers are all above 370 °C,showing their good thermal stability;polymer P5 can self-assemble into fibrous;Space Charge Limited Current(SCLC)tests show that these polymers are typical electron transporting materials.2)Imide groups were introduced to conjungated core of the subphthalocyanine,three corressponding compounds were synthesized by a multi-step synthesis.and their optical,electrochemical and solar cell properties were studied.The results show that their LUMO levels can be significantly lowered by introducing imide groups to the subphthalocyanine.Their LUMO energy levels are between-3.95 and-3.98 e V,which are about 0.4 e V lower than those of unmodified subphthalocyanine,indicating their strong electron accepting capabilities.The solution absorption of these acceptor materials red-shifts by 25 nm compared to the unmodified subphthalocyanine wavelength.They has strong absorption in the range of 450 to630 nm.The optical bandgap is 1.93 e V.Bulk heterojunction solar cells with reverse structure were prepared using a subphthalocyanine derivative as an acceptor material and a PBDB-T-SF donor material.The highest photoelectric conversion efficiencies of the three compounds 7a,7b,and 8a were 1.05%,2.23%,1.30%.