摘要
We successfully designed and synthesized two BDT-BT-T （BDT=benzo[1,2-b：4,5-b＇]dithiophene, BT-T=4,7-dithien-2-yl-2,1,3-benzothia- diazole） based polymers as the electron donor for application in all-polymer solar cells （all-PSCs）. By adopting N2200 as the electron acceptor, we system- atically investigated the impact of fluorination on the charge transfer, transport, blend morphology and photovoltaic properties of the relevant alI-PSCs. A best power conversion efficiency （PCE） of 3.4% was obtained for fluorinated PT-BT2F/N2200 （BT2F=difluorobenzo[c][1,2,5]thiadiazole） alI-PSCs in com- parison with that of 2.7% in non-fluorinated PT-BT/N2200 （BT=benzothiad（azole） based device. Herein, all-polymers blends adopting either non-fluori- nated PT-BT or fluorinated PT-BT2F exhibit similar morphology features. In depth optical spectrum measurements demonstrate that molecular fluorina- tion can further enhance charge transfer between donor and acceptor polymer. Moreover, all-polymer blends exhibit improved hole mobilities and more balanced carriers transport when adopting fluorinated donor polymer PT-BT2F. Therefore, although the PCE is relatively low, our findings may become important in understanding how subtle changes in molecular structure impact relevant optoelectronic properties and further improve the performance of all-PSCSs.
We successfully designed and synthesized two BDT-BT-T （BDT=benzo[1,2-b：4,5-b＇]dithiophene, BT-T=4,7-dithien-2-yl-2,1,3-benzothia- diazole） based polymers as the electron donor for application in all-polymer solar cells （all-PSCs）. By adopting N2200 as the electron acceptor, we system- atically investigated the impact of fluorination on the charge transfer, transport, blend morphology and photovoltaic properties of the relevant alI-PSCs. A best power conversion efficiency （PCE） of 3.4% was obtained for fluorinated PT-BT2F/N2200 （BT2F=difluorobenzo[c][1,2,5]thiadiazole） alI-PSCs in com- parison with that of 2.7% in non-fluorinated PT-BT/N2200 （BT=benzothiad（azole） based device. Herein, all-polymers blends adopting either non-fluori- nated PT-BT or fluorinated PT-BT2F exhibit similar morphology features. In depth optical spectrum measurements demonstrate that molecular fluorina- tion can further enhance charge transfer between donor and acceptor polymer. Moreover, all-polymer blends exhibit improved hole mobilities and more balanced carriers transport when adopting fluorinated donor polymer PT-BT2F. Therefore, although the PCE is relatively low, our findings may become important in understanding how subtle changes in molecular structure impact relevant optoelectronic properties and further improve the performance of all-PSCSs.
基金
This work was supported jects （No. 2016YFA0202402）, by the National Key Research Pro- the Natural Science Foundation of Jiangsu Province of China （BK20170337）, the National Natural Science Foundation of China （Nos. 51761145013 and 61674111）, and ＂111＂ projects. And we also acknowledge the Collaborative Innovation Center of Suzhou Nano Science and Technology, the Priority Academic Program Development of Jiangsu Higher Educa- tion Institutions （PAPD）.
