Preparation Of Pyran Based Electron Acceptors And Their Photovoltaic Properties

In recent years,polymer solar cells have been rapidly advanced and non-fullerene acceptors(NFAs)have received extensive attentions.With the constantly emerging of new building blocks,a lot of high-efficiency NFAs were reported and the power conversion efficiency(PCE)of the corresponding polymer solar cells(PSCs)exceeded 15%,which may ascribed to the tunable UV-vis absorption spectra and the adjustable energy levels.In this manuscript,two kinds of pyran based acceptors were successfully designed and synthesized,which including the fused five-membered based pyran acceptors and the supramolecular fused-ring acceptors.The structure-property relationships have been studied and they are also applied into PSC device fabrication.The details are as following:1.Mono-pyran based Five-membered Fused Ring Acceptor: Synthesis and Photovoltaic Properties.Based on our previous study on dibenzopyran and ladder type bipyran based donors and acceptors,we designed and synthesized a novel five-membered fused mono-pyran building block in this work.By introducing different thiophene-? bridges containing varied number of alkoxy side chains,a series of mono-pyran small molecule acceptor materials(TM 1-5)were synthesized.The basic properties of these materials were studied,such as ultraviolet-visible absorption spectra,electrochemistry properties.In addition,these materials were also applied into PSCs fabrication and the preliminary results indicated that TM1 achieved the best PCE of 3.43%(Voc=0.76 V,Jsc=8.91 m A/cm2,FF=50.55)when PBDB-T was used as electronic donor component.2.Dithienopyran based Supramolecular Fused Ring Acceptors: Synthesis and Photovoltaic Properties.Supramolecular fused ring acceptors could effectively reduce the synthetic expense due to the simplicity of the constructing building block,which would greatly reduce the synthetic challenge.In this work,the three membered dithienopyran was utilized as the main unit and when it was connected to the difluorobenzene or dialkoxybenzene fragments via Stille cross-coupling,a series of fragments with supramolecular fused-ring characters were prepared.After the end capping with the electron deficient block,a series of supramolecular NFAs could be obtained as TM 6-8.Due to the existence of the supramolecular interactions such as S···O and F···S in the structure,the molecular skeleton tend to present the planar conformations.All the aimed molecules and the precursors have been characterized by 1HNMR,13 CNMR and HRMS.The basic properties of these materials were studied,such as ultraviolet-visible absorption spectra,electrochemistry properties and the absorption spectra could extend to 1000 nm.In addition,these materials were also applied into PSCs fabrication and the preliminary photovoltaic results were collected.