| Organic solar cells have attracted attention due to their light weight,flexibility,mechanical flexibility,and low costs.In the past 40 years,the efficiency of organic solar cells has exceeded 17%from the original 1%to the present.Small molecule acceptors have played a key role.In this thesis,we have mainly carried out the following two aspects of work:Based on the dithienothiophen[3,2-b]pyrrolobenzothiadiazole（BTP）core,we have developed two novel non-fullerene acceptor materials,C4 and C6.We found that they have similar optical and electrochemical properties.Then a detailed study of their photovoltaic performance was conducted,we found their photovoltaic performance are significantly different.The resulting PM6:C4 device yielding a best PCE of 6.64%with a VOCof 0.70V,a JSC of 14.49 m A/cm2,and FF of 65.53%and the resulting PM6:C6device yielding a best PCE of 14.54%with a VOCof 0.84V,a JSC of 23.82 m A/cm2,and FF of 72.68%.We conducted a detailed analysis of the reasons for these differences.Through detailed tests on the exciton dissociation probability,light intensity dependence,the electron mobility of the device and their morphology,we found that based on PM6:C6 system solar cells possess high exciton dissociation probability,small charge recombination,high device mobility,and better morphology when mixed with PM6.It can promote to achieve high efficiency organic solar cell.We designed and synthesized two novel non-fullerene acceptors,BTAC4 and BTAC6.The absorption in the solution and energy levels of the two acceptors were similar,but there was a large difference between the absorption in the film,which may be ascribed to different aggregation states during the process from solution to film.Then we characterize their photovoltaic performance,the devices based on PM6:BTAC4exhibit a best PCE of 10.80%with a VOC of 0.89V,a JSC of 19.84 m A/cm2,and FF of61.25%while devices based on PM6:BTAC6 exhibit a best PCE of 10.11%with a VOCof 0.89V,a JSC of 17.78 m A/cm2,and FF of 64.07%. |
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