Synthesis And Properties Of Organic Acceptor Materials Based On Indacenodithiophene

Traditional fossil energy brings great pollution to the environment,so it is urgent to seek new renewable energy.In recent years,solar energy has become a research hotspot,because it is rich,clean and pollution-free in resources.The mechanical properties and stability of all polymer solar cells are satisfactory.For the polymer acceptors based on naphthalene diimide(NDI)and perylene diimide(PDI),their absorption coefficient arelow,which limit the further improvement ofpower conversion efficiency.Therefore,the research and development of new polymer acceptor materials is of great significance to improve the energy conversion efficiency of all polymer organic solar cells and even to the future industrialization.In the second chapter,we designed and synthesized the polymer acceptors,PIDIC2T,PIDIC2T2F and PIDIC2T2C1 based on 2,2’-((2Z,2’ Z)-((4,4,9,9-tetrahexadecyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-2,7-diyl)bis-(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile,with bithiophene,fluorinated bithiophene and chloridized bithiophene as linking units.UV absorption and electrochemical tests show that halogen substitution has little effect on the optical absorption and electrochemical properties.However,the performance of the device is obviously different,because the carrier mobility and the device morphology are quite different,resulting in the increase of the fill factor from 44%to 62%,which improves the photoelectric conversion efficiency.The efficiency of the device based on PIDIC2T2C1 is the best,reaching 7.11%.In the third chapter,we designed and synthesized the small molecule receptor IDIC2T based on indacenodithiophene,and used the small molecule IDIC2T as the active chain segment to alternately connect with different length alkyl thiophene to synthesize four kinds of multi segmented polymer acceptors,PIDIC2TN3,PIDIC2TN4,PIDIC2TN5 and PIDIC2TN6.The results of UV absorption show that the absorption spectrum of the polymer is almost the same as that of the polymer in the solution state,while the absorption spectrum of the polymer in the film state is slightly blue shifted.Electrochemical studies show that the energy level structures of small molecules and multi segmented polymers are similar.At the same time,the inverted solar cell was prepared with PM6 as polymer donor.The results show that the photoelectric conversion efficiency based on small molecule IDIC2T is only 2.81%,while the photoelectric conversion efficiency based on polymer PIDIC2TN3 is 6.25%.The reason is that PIDIC2TN3 has higher short-circuit current density and fill factor.In the fourth chapter,we designed and synthesized the receptor polymer PIDICOBDT based on indacenodithiophene,which is not covalently linked to the conformation lock.Research shows that due to the interaction of O…S,O…H makes PIDICOBDT show more regular conjugate plane,excellent optical absorption performance and suitable energy level.All polymer solar cells based on PIDICOBDT were prepared with PBDB-T as the donor material.It was found that the photoelectric conversion efficiency increased from 4.08%to 6.20%under annealing condition.