Synthesis And Properties Of Donor Materials Based On S, N-Heteroheptacenes For Organic Solar Cells

Solar energy, as a safe, clean and renewable energy, has played an important role in resolving the energy depletion and environmental pollution in today's world. Solar cells provide an effective way to use solar energy and they can convert solar energy into electric energy directly. Organic thin-film solar cells, which are new types of solar cells, have become a research focus owing to their simple preparation, abundant material resource and large area fabrication on flexible substrates. However, the low power conversion efficiency of thin-film solar cells limits their industrialization development.The excellent organic donor materials often require good stability, high hole mobility, matched energy levels with acceptors, wide and efficient absorption. In this paper, we designed and synthesized a series of A-D-A type small molecular donor materials ZY1-ZY3, containing S, N-heteroheptacenes as electron-donating unit and dicyanovinyl or ethyl cyanoacetate as electron-withdrawing unit. The structures of ZY1-ZY3 were characterized by HRMS,1H-NMR and 13C-NMR.The photophysical and electrochemical properties of ZY1-ZY3 have been investigated by UV-Vis absorbance, fluorescence quenching and cyclic voltammetry experiment. The results indicated that ZY1-ZY3 had strong absortion in 400-700nm and their values of HOMO and LUMO energy levels were matched with acceptor PCBM, so they are appropriate to be applied in organic thin-film solar cells. In addition, the solution-processing bulk-heterojunction (BHJ) solar cells were also prepared by using ZY1-ZY3 as donors and PC61BM as acceptor and the power conversion efficiency of PV device based on ZY1 is 1.09%.