Synthesis And Performance Research Of Novel Small Molecule Photovoltaic Acceptor Materials Based On Functionalized Quinoxaline Fromwork Cores

With the rapid development of society’s increasing demand for energy,problems such as energy depletion and environmental pollution due to the huge consumption of fossil energy have become important issues facing global development.As a new energy source,organic solar cells have attracted much attention due to their light weight,simple process,solution process ability,and large area devices.The research status of organic solar cells（PSCs）were summarized in this dissertation.To address key scientific issues such as the lack of current high-efficiency small molecule acceptor materials and the unclear relationship between molecular structure and performance.In this thesis,A-π-A’-π-A structure linear organic small molecule electron acceptor materials were constructed by the quinoxaline derivatives as electron-deficient central skeleton core（A’）units,thiophene asπbridges,and cyanoindanone derivatives as terminal acceptor（A）units;The chemical structures of monomers and target small molecules were characterized by ¹H NMR and ¹³C NMR.Furthermore,their thermal stabilities,optical,electrochemical and photovoltaic properties were systematically studied.With these small molecules as the receptor materials,the bulk heterojunction polymer solar photovoltaic devices were made,and their photovoltaic properties are systematically investigated.The main research contents and conclusions of this thesis are as follows:（1）Two linear nonfullerene electron accepter materials,BDTDFQx and BDTDFQx-4F,were designed and synthesized by using cyanoindone derivative as terminal acceptor（A）group,dithiophene quinoxaline derivative as central electron-deficient（A’）unit and alkylthiophene asπbridge.The effects of BDTDFQx and BDTDFQx-4F on photophysics,electrochemistry,thermal stability and photovoltaic performance were systematically studied.The two components based on PBDB-T:BDTDFQx and PBDB-T:BDTDFQx-4F have only obtained 2.26%and 0.08%PCE.The three components based on PBDB-T:BDTDFQx:N2200 and PBDB-T:BDTDFQx-4F:N2200 obtained 7.42%and 7.17%PCE,respectively.（2）In view of the defects of poor miscibility and easy aggregation of the above materials,A class of A-π-A’-π-A linear electron accepter material BDTDFQx-TT4F was designed and synthesized by grafting oxygen alkyl bridge at different positions of quinoxoline derivatives.The photophysics,electrochemistry,thermal stability and photovoltaic properties of BDTDFQx-TT4F were systematically studied.The findings:The introduction of oxyalkylthiophene improved the molecular solubility,widened the absorption spectrum and enhanced the charge transfer capacity.The tri-component based on PBDB-T:BDTDFQx-TT4F:N2200 obtained 8.04%PCE,with a V_OCof 0.89V,a J_SCof 12.81 m A cm^-2and a FF of 70.77%（3）In order to avoid the aggregation of the acceptor material H and reduce the rigidity and plane accumulation of the material,an oxyalkyl chain with steric effect was introduced into the donor unit of the main chain to design and synthesze DCl Qx-O8,DCl Qx-O24 and DCl Qx-O24Me,The photophysics,electrochemistry,thermal stability and photovoltaic properties of small molecules DCl Qx-O24 and DCl Qx-O24Me have been systematically studied.0.69%and 0.83%PCE was obtained for two components based on PM6:DCl Qx-O24 and PBDB-T:DCl Qx-O24.