Study On Synthesis And Performance Of Electron Acceptor Materials Based On TIPS-benzothiophene

Organic solar cells have attracted widespread attention in the scientific research community due to their advantages of being flexible,translucent and easy to manufacture in large areas.Active layer materials are the key and foundation of organic solar cells research.Early researches are mainly based on the design and synthesis of polymer donor materials.Recently,small molecule organic solar cells based on solution processing have developed quickly.This thesis is based on 4,8-bis(triisopropylsilylethynyl)benzo[1,2-b:4,5-b']dithiophene(BDT-TIPS)and 5,10-bis(triisopropylsilylethynyl)dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene(DTBDT-TIPS)two structures unit then six kinds of small molecule acceptor materials are synthesized.A polymer acceptor material is synthesized based on the1,8-naphthalene diimide(NDI)structural unit and their structure and properties are characterized.The main contents are as follows:In chapter 2,two organic small molecules BDTTIPS-PDI and DTBDTTIPS-PDI are synthesized of 1-bromo-N,N'-bis(2-hexyldecyl)perylene-3,4,9,10-tetracarboxylic acid diimide with BDT-TIPS and DTBDT-TIPS by the Stille coupling reaction.Their optical band gaps are1.87 e V and 1.72 e V.The highest occupied molecular orbital(HOMO)energy levels EHOMO are-6.12 e V and-5.94 e V.The lowest unoccupied molecular orbital(LUMO)energy levels ELUMO are-4.25 e V and-4.22 e V.A solar cell device is prepared using polymer PBDT-DTNTC6 as donor material and small molecules BDTTIPS-PDI and DTBDTTIPS-PDI as acceptor materials.The device is optimized which the mass ratio of PBDT-DTNTC6:BDTTIPS-PDI is 1:2.The highest power conversion efficiency(PCE)is 2.02% and an open circuit voltage(Voc)is 0.78 V,short circuit current(Jsc)is 5.52 m A/cm2 and fill factor(FF)is47.15%.In chapter 3,four organic small molecule acceptor materials BDTTIPS-NPI,BDTTIPS-T-NPI,DTBDTTIPS-NPI and DTBDTTIPS-T-NPI are synthesized of N-(2-ethylhexyl)-4-bromo-1,8-naphthalimide and N-(2-ethylhexyl)-4-(5-bromothien-2-yl)-1,8-naphthalimide with BDT-TIPS and DTBDT-TIPS by the Stille coupling reaction.Their optical band gaps are 2.36 e V,2.19 e V,2.26 e V and 1.95 e V,respectively.EHOMO are-5.99 e V,-5.73 e V,-5.86 e V and-5.51 e V,respectively.ELUMO are-3.63 e V,-3.54 e V,-3.6 e V and-3.56 e V,respectively.The polymer donor PBDTTSC12-FTAZ are synthesized between2,6-bis(trimethyltin)-4,8-bis(5-(2-butyloctylthio)thien-2-yl)benzo[1,2-b:4,5-b']dithiophene,and 4,7-bis(5-bromothien-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-2H-benzo[d][1,2,3]triazole by the Stille coupling reaction.The polymer PBDTTSC12-FTAZ is used as a donor material to prepare solar cell devices with four small-molecule acceptor materials and the energy conversion efficiency is not high.The photoluminescence properties are measured after themass ratio of the donor receptors is 1:1.The results showed that the polymer donor PBDTTSC12-FTAZ exhibited fluorescence quenching after doping with different small molecule receptors.In chapter 4,polymer acceptor material PNDI-TBF is synthesized of N,N'-bis(2-octyldodecyl)-2,6-dibromonaphthalene-1,4,5,8-tetracarboxylic acid bisimide,and 5,5'-bis(trimethyltin)-2,2'-(2,3-difluoro-1,4-phenylene)dithiophene by Stille coupling reaction.The optical band gap of the polymer is 1.70 e V.EHOMO and ELUMO are-6.27 e V and-4.55 e V,respectively.Polymer PNDI-TBF used as the acceptor and polymer PBDTTSC12-FTAZ used as donor to prepare all-polymer solar cells.The PCE of the device is the highest when the mass ratio of PPBDTTSC12-FTAZ: PNDI-TBF is 2:1 with a VOC of 0.91 V,JSC of 7.88 m A/cm2 and FF of 43.02%.