Research On Novel Donor Photovoltaic Materials Containing Extended Benzodithiophene Unit

In this dissertation,two kindsof organic donor photovoltaic materials based on two dimensional(2D)conjugated naphthodithiophene(NDT),polymers and small molecules,were designed and synthesized.The relationship between molecular structure and photovoltaic property was studied.Moreover,a novel all-small-molecule ternary organic solar cell based on two different benzodithiophene(BDT)type small molecules and PC71 BM was constructed and the photovoltaic property of corresponding device was also studied.Two novel donor–acceptor(D-A)copolymers based on 2D conjugated NDT as the donor and alkylthieno[3,4-c]pyrrole-4,6-dione(TPD)as the acceptor with different alkyl substituted thiophene-bridges,PzNDTT-TPD1 and PzNDTT-TPD2,have been designed and synthesized.The photovoltaic property of PzNDTT-TPD1-based device was much better than that of PzNDTT-TPD2 and the best power conversion efficiency(PCE)reaches 7.5% at an active layer thickness of 200 nm.Two novel acceptor–donor–acceptor(A–D–A)type small molecules based on 2D conjugated NDT as the donor and cyanoacetate as the acceptor,named as NDTT-CNCOO and NDTP-CNCOO,have been designed and synthesized.The photovoltaic property of NDTP-CNCOO-based device was much better than that of NDTT-CNCOO and the best PCE reaches 7.2% at an active layer thickness of 300 nm,which is the best result reported for NDT-based small molecule organic solar cells to date.A novel small molecule donor photovoltaic material,named as DR3TBDTT-E,has been designed and synthesized,which can be seen as the extended structure of DR3 TBDTT along the vertical axis.The photovoltaic property of ternary(DR3TBDTT+DR3TBDTT-E /PC71BM)organic solar cell was much better than that of binary DR3TBDTT/PC71 BM system and the best PCE reaches 10.1%,which is the best result reported for all-small-molecule ternary organic solar cells.