Design,Synthesis And Photoelectric Property Of Acceptor-Donor-Acceptor Type Acceptor Based On Indacenodithiazole For Small Molecule Organic Solar Cells

In this paper,a series of linear A-D-A(Acceptor-Donor-Acceptor)type small molecules based on indacenodithiazole(IDTz)core were designed and synthesized for the application as acceptor materials for non-fullerene organic solar cells.photophysical and electrochemical properties of these molecules were studied.The main work includes two parts :In the first part,Four A-D-A type small molecules based on indacenodithiazole(IDTz)core with different alkyl side chains were designed and synthesized by Stille coupling as non-fullerene acceptor materials for organic solar cells: IDTzC12DPP(indacenodithiazole donor core with dodecyl and terminal acceptor unit diketopyrrolopyrrole with Thiophene)、IDTzC12NDPP(indacenodithiazole donor core with dodecyl and terminal acceptor unit diketopyrrolopyrrole with Thiazole)、IDTzEHNDPP(indacenodithiazole donor core with ethylhexyl and terminal acceptor unit diketopyrrolopyrrole with Thiophene)and IDTzC6NDPP(indacenodithiazole donor core with hexyl and terminal acceptor unit diketopyrrolopyrrole with Thiophene).The structure and purity of target compounds were detected by nuclear magnetic resonance and mass spectrometry.With the same conjugated skeleton,the four molecules in the thin film state showed similar absorption spectra,and their optical band gap that were 1.74 eV、1.74 eV、1.71 eV and 1.73 eV have not varied obviously.because thiazole attraced eletrons easier than thiophene,the HOMO and LUMO energy level of the three molecules with end group based on DPP substituted by thiazole were slightly lower than that of IDTzC12 DPP with end group based on DPP subetituted by thiophene.The two molecules of IDTzC12 DPP and IDTzEHNDPP Having not the ability to form film leads to impossibility to measure the efficiency of the device.The molecular of IDTzC12 NDPP formed film a little bit better than that of the two molecules of IDTzC12 DPP and IDTzEHNDPP,Yet the device based on IDTzC12NDPP/P3 HT achieved a PCE of 0.6%.In the second part,Two A-D-A(Acceptor-Donor-Acceptor)type small molecules with two-dimension conjugation were designed and synthesized as non-fullerene acceptor materials for organic solar cells.The two two-dimensional conjugation cores were synthesied by Corey-Fuchs 、coupling reaction and so on,And finally the two acceptor units diketopyrrolopyrrole substituted by thiazole and isoindigo were linked respectively to the donor core unit by one step Stille coupling reaction to get IDTzNDPP(indacenodithiazole donor core with thiophene substituted by ethylhexyl and terminal acceptor unit diketopyrrolopyrrole with Thiazole)and IDTzIID(indacenodithiazole donor core with thiophene substituted by ethylhexyl and isoindigo).The structure and purity of target compounds were detected by nuclear magnetic resonance and mass spectrometry.Due to the increasing conjugated system,the HOMO and LUMO energy levels of IDTzNDPP were slightly higher than that of IDTzC12 NDPP.And the maximum absorption spectra of IDTzNDPP was red shifted by 46 nm and broadened against IDTzC12 NDPP,and the optical band gap of IDTzNDPP that was 1.55 eV was narrower than that of IDTzC12 NDPP which was 1.74 eV.the HOMO and LUMO energy level of IDTzNDPP based on DPP substituted by thiazole were slightly lower than that of IDTzIID.And the maximum absorption spectra of IDTzNDPP was red shifted by 39 nm and broadened against IDTzIID.The spectral absorption range and the energy level of the target compounds were adjusted by introduce different end groups in this paper.