Synthesis Of Wide Bandgap Conjugated Polymers Containing Imide-functonalized Benzotrizole Units And Their Applications For Polymer Solar Cells

With the developing of human society,the energy crisis and environmental issues have become hot spots in today's society.The traditional natural resources such as coal,petroleum and natural gas can no longer meet the needs of human development.Environmental pollution has also become a serious problem to be solved urgently.Solar energy,as a renewable energy source,has drawn much attention for its remarkable advantages such as inexhaustible,pollution-free and noise-free,and without geographic restrictions.Polymer / organic solar cells have the following salient advantages:(1)the manufacturing process is simple and low energy consumption,in particular,can be processed at room temperature solution can also be achieved roll to roll(roll to roll)processing;(2)Light weight,full printing can be achieved for largescale production;(3)a wide range of use,and will not because of the environment,origin and the impact of its use.For the above reasons,polymer solar cells have become the research focus of today's research scholars.From the late fifties of last century,with the joint efforts of numerous scientific researchers,the energy conversion efficiency of single-layer non-fullerene organic solar cells has exceeded 13% so far.TzBI type polymers in the wide bandgap polymer performance is good,so we can make a series of molecular modifications for this unit,including the main chain and side chain;main chain modification can be replaced D unit to start,with reference to 4T class of copolymerization 4T has excellent properties both in fullerenes and non-fullerenes,regardless of its combination with BT,NT or BTA.Meanwhile,Tz BI units can improve their crystallinity by copolymerization with 4T due to their planarity;meanwhile,Its wide bandgap characteristics.In chapter two,PTzBI-TBO containing long alkyl chains was designed and synthesized.The PTzBI-TBO-DFDT,PTzBI-TBO-DT and TzBI-Both polymers have good thermal stability,broad absorption and well-matched ITICs,but the absorption coefficient of PTzBI-TBO-DT is lower than that of PTz BI-TBO-DFDT,which is unfavorable for device performance.The photovoltaic performance of the polymer was also investigated.The device efficiencies of PTzBI-TBO-DFDT and PTzBI-TBO-DT prepared by ITIC were 2.83% and 0.05%,respectively.The device efficiency of PTzBI-TBO-DT and ITIC was significantly lower The device efficiencies of PTz BI-TBO-DFDT and ITIC,which may have lower electron mobility than the PTzBI-TBO-DFDT versus the polymer PTzBI-TBO-DT and ITIC devices,closely related.In conclusion,the device efficiency of polymer PTzBI-TBO-DT and ITIC is lower than that of polymer PTz BI-TBO-DFDT and ITIC device,which may be related to absorption coefficient,hole mobility and film morphology.In the third chapter of this paper,we found that the solubility of TzBI and tetrakis thiophene was solved by introducing the long alkyl chains on thiophene,while maintaining the characteristics of its wide bandgap.However,due to the introduction of long alkyl chains,its miscibility with ITIC is poor,with a large phase separation,resulting in lower device efficiency.In view of a few of the issues that emerged from the previous chapter,alkyl chains are now introduced into the TzBI nucleus.PTzBI-OD-DFDT and PTzBI-OD-TT were obtained by the Stille polymerization of bis-tin-bifluorothiophene and bis-tin-bithiophene,respectively.The thermal stability,photophysical properties and electrochemical properties of the two polymers were studied respectively.These properties of the polymer are similar to the PTzBI-TBO-DFDT and PTzBI-TBO-DT polymers synthesized in the previous chapter,except that the absorption coefficients of the PTz BI-OD-DFDT and PTz BI-OD-TT polymers are relatively high.Furthermore,the photovoltaic performances of the devices were studied.The device efficiencies of PTzBI-OD-DFDT and PTzBI-OD-TT prepared by ITIC were 4.90% and 2.35%,respectively.The device efficiency was significantly higher than that of the previous device.In contrast,the device mobility and the film surface topography of the blend films of PTzBI-ODDFDT,PTzBI-OD-TT and ITIC may be responsible for the higher device efficiency.