Synthesis And Properties Of D-A Type Organic Small Molecule Photovoltaic Materials Based On Indacenodithiophene And Indenothiophene

In recent years,organic photovoltaics(OPVs)have developed rapidly,and the device efficiency has reached the commercial application requirements.The photoactive active layer materials(donor and acceptor material)and device optimization are the key to batteries for obtaining high-efficiency.The former is the foundation and precondition.In order to improve the photovoltaic properties and enrich the variety of donor materials,this paper aims to improve the molecular fill factor(FF)and carrier mobility by changing the terminal group and regulating the interaction between the terminal donor unit(D)and the acceptor unit(A),and raise the short-circuit current(Jsc)of the device by adjusting ?-bridge with different conjugation degrees,widening the molecular absorption spectrum as well as matching with the solar spectrum to a greater extent.Based on these factors,two kinds of organic small molecule donor materials were designed and synthesized,and their chemical structures were confirmed.The thermal stability,crystallization,photophysical and electrochemical properties of the target compounds were systematically studied.The charge-transport properties,morphology of active layer blend films and photovoltaic properties of monolayer bulk heterojunction organic solar cells(BHJ-OPVs)were investigated.The studied results are mainly presented as follows:1.Two novel symmetric organic small molecules of(Cz-T-2FBT)2IDT and(Cz-TT-2FBT)2IDT with a indacenodithiophene(IDT)central donor core,fluorinated benzothiadiazole(2FBT)as acceptor,thiophene(T)or thienothiophene(TT)as?-bridged units and 3-carbazole unit as terminal group were designed and synthesized.The results show that the carbazole as the terminal group can improve the stacking and self-assembly behavior of molecules,which is beneficial to the improvement of molecular properties;the molecular structure with better conjugacy and planarity is good to attain high Jsc.Finally,the(Cz-T-2FBT)2IDT-based BHJ-OPVs with PC71BM as an electron acceptor showed a maximum power conversion efficiency(PCE)of 5.93%.2.Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)2 and IT(2FBT-TT3Cz)2 with a indenothiophene(IT)central donor core,2FBT as acceptor,T or TT as ?-bridged units and 3-carbazole unit as terminal group were designed and synthesized.The results show that changing the terminal group and regulating the interaction of the terminal D-A can promote the Jsc,and the FF of the molecule distinctly.Finally,the maximum PCE of 5.81%with a high Voc of 0.97 V was obtained in the IT(2FBT-T3Cz)2-based BHJ-OPVs with PC71BM as an electron acceptor,which is one of the highest values for OSCs reported for the IT-based SMs donors.