Developing And Properties Of Organic Photovoltaic Materials Based On Indacenodithiophene And Indacenodithienothiophene Groups

As we all know,solar cells are a research hotspot in the energy field and an important topic that is difficult to overcome.As a new energy technology,organic/polymer solar cells have the advantages of light material quality,wide absorption range,large-scale production through solvent processing and the manufacture of flexible and translucent devices.In recent years,a large number of organic solar cell materials with novel structures and excellent performance have been developed.So far,the energy conversion efficiency?PCE?of laminated organic solar cells based on non-fullerene acceptor materials has jumped to 17.3%,indicating the broad application potential of organic solar cell technology.This paper briefly describes the development of organic solar cells,and systematically summarizes and expounds the non-fullerene small molecule receptor materials.And for the current electron-withdrawing Donor-Acceptor-Donor group?A-D-A?type non-fullerene small molecule receptors?SMAs?,the construction method is relatively simple,and the relationship between structure and performance is not thorough enough.SMAs of type A-D₁-D₂-D₁-A and A-D-D-A,and A-D-A type SMAs modified with benzothiophene fused ring at the molecular end.The effect of the conjugation effect of the molecule on the HOMO energy level,the modification of the F atom,the morphology of the active layer film and the self-assembly behavior of the molecule,as well as the photovoltaic performance of the solar cell and the charge mobility of the material,The intrinsic relationship between absorption spectrum and electron energy level reveals the correspondence between molecular structure and photovoltaic performance parameters.This paper provides a reference for the design of high-efficiency organic solar cells.The research contents and experimental results of this paper are summarized as follows:?1?The 2-?3-oxo-2,3-dihydro-1H-inden-1-ylidene?malononitrile?IC?and its difluoro-substituted IC?DFIC?are used as terminal acceptor units to synthesize based on Indacenodithiophene?IDT?and benzo[1,2-b:4,5-b']dithiophen?BDT?A-D₁-D₂-D₁-A type narrow band gap small molecule receptor BDT?IDT-IC?₂ and BDT?IDT-IC-2F?₂.The optical band gaps of BDT?IDT-IC?₂ and BDT?IDT-IC-2F?₂are 1.59 eV and 1.54 eV,respectively.When PBDB-T was used as the donor material,PSCs based on BDT?IDT-IC?2 and BDT?IDT-IC-2F?2 achieved PCEs for 4.98%and6.21%,respectively.?2?Two A-D-D-A type SMAs IDT₂-IC-4F and C₆IDT₂-IC-4F were designed and synthesized.The photophysical,electrochemical and photovoltaic properties were studied.The study found that IDT₂-IC-4F and C₆IDT₂-IC-4F exhibit distinct properties from the classical A-D-A-type small molecule?ITIC?,which have a higher HOMO level?-5.40 eV?and a narrower spectral band gap.?E_g¹.40 eV?extends the absorption spectrum to 870 nm and 885 nm.When blended with the polymer donor PBDB-T,SMAs showed good photovoltaic performance,based on PBDB-T:IDT2-IC-4F PSCs,showing a higher PCE?10.06%?,where short-circuit current?Jsc?and fill factor?FF?were 16.00 mA cm^-2 and 69.22%,respectively.The photovoltaic device based on PBDB-T:C6IDT2-IC-4F blend film also achieved PCE for 9.60%,especially J_sc reached 17.64 mA cm^-2,while V_occ and FF decreased.?3?A novel non-fullerene terminal electron-withdrawing unit was developed.The unit skeleton of the terminal acceptor was constructed by replacing the benzene unit with a larger planar benzothiophene unit,and the A-D-A-type SMAs IT-BT based on IDTT was synthesized.The effects of the change of terminal structure on the molecular packing mode,morphology,absorption spectrum,electronic energy level and the parameters of photovoltaic performance of SMAs were discussed.The spectral properties between benzene,benzothiophene and thiophene were discussed.The gradual relationship with the LUMO level and the effect on the PCEs of the battery.Among them,based on the polymer PBDB-T solar cell,IT-BT realized PCEs of 8.17%.