Synthesis And Investigation Of Perylene Diimides-based Accptors For Bulk Heterojunction Organic Solar Cell Applications

With rapid change of global energy-resource structure,human-being take more concentrated on developing recycle and environment-friendly energy,increasing demand of novel materials and their devices.As a star candidate to replace traditional fossil energy,organic solar cells（OSCs）are still in choke point during the development process due to their low power conversion efficiency.In this thesis,we focus on the control strategy of absorption spectrum,Frontier Molecular Orbital levels,molecular conformation,the aggregation state of the molecule and intramolecular/intermolecular interaction,and have designed and synthesized a series of PDI-based acceptor molecules.The main research contents are as follows:1.We have designed and synthesized a series of A1-D-A2 type SMAs,which carbazole as the D unit,PDI as the A₁ unit,and 2-（3-Oxo-indan-1-ylidene）-malononitrile/3-（Dicyanomethylidene）indan-1-one as the A₂ unit,named RPC,FRPC,IPC and FIPC.Among them,FIPC exhibited strongest intramolecular charge transfer（ICT）,extended effectiveπ-conjugation and coplanar structure,which benefited exciton dissociation and charge transport.Highest power conversion efficiency（PCE）of 3.27%has been achieved using the blend of FIPC:PTB7-Th with V_OC of 0.94 V,J_SC of 9.05 mA/cm²and FF of 38.6%,profit from some domain size.2.We have designed and synthesized a novel SMA TP-ZnP,which introduce porphyrin as spacer,connecting spacer and PDIs with triphenylamine and exhibited 3D structure,weak intermolecular interactions and molecular aggregation,good thermal stability,broad and strong absorption in the visible region and optical band gap of 1.90 eV.The device based on PTB7-Th:TP-ZnP showed a highest PCE of 7.65%with V_OCC of 0.84 V,J_SC of 14.53 mA/cm² and FF of 62.7%.3.We have designed and synthesized conjugated copolymer acceptors P1 and P2,which connect 3,3’-Difluoro-2,2’-bithiophene with PDI unit and small amount of porphyrin unit.We studied their thermal,photophysical and electrochemical properties.The results show that they have good thermal stability,outstanding absorption in the range of 400-700 nm.The HOMO and LUMO levels of P1 are-5.80 eV and-3.89 eV,respectively,while the electrochemical band gap was 1.91 eV.The HOMO and LUMO levels of P2 are–5.82 eV and-3.88 eV,respectively,while the electrochemical band gap was 1.94 eV.