Synthesis And Photovoltaic Applications Of Asymmetric Fused-Ring Non-Fullerene Small Molecular Acceptors And Random Conjugated Terpolymers

The performance of active layer materials plays a decisive role in power conversion efficiency（PCE）of organic solar cells（OSCs）,and it’s also one of the key factors to improve device performance.Generally,the active layer materials include acceptor materials and donor materials.Donor materials include polymer donors and small-molecule donors,small-molecule acceptors and polymer acceptors consist of acceptor materials based on the active layer materials of OSCs,a series of small-molecule acceptors（SMAs）and polymer donor materials were designed and synthesized.We did a concrete and detailed study on their photovoltaic applications in this paper.1.On the basis of high-performance non-fullerene small-molecule acceptor Y6,we synthesized three asymmetrical SMAs by using Cl atoms substituted F atoms on 3-dicyanogenmethylene-1-indone terminal group,namely SY1（two F atoms and one Cl atom）,SY2（two F atoms and two Cl atoms）,SY3（three Cl atoms）.In addition,we also synthesized previous reported Y6（four F atoms）and Y6-4Cl（four Cl atoms）as contrast materials.Among the five compounds,SY1 possesses the highest lowest unoccupied molecular orbital（LUMO）energy level and excellent intermolecular stacking.OSCs based on donor material PM6 and acceptor material SY1 were prepared.As a result,an outstanding PCE of 16.83%was achieved,with a good V_oc of 0.871 V and a high FF of 76%.The high FF is attributed to more balance charge transport and more optimal morphology of active layer for the PM6:SY1-based device.2.In this study,we synthesized two“double-acceptor type”random conjugated terpolymer（RCT）donors,named by PBDB-TAZ20 and PBDB-TAZ40.The addictive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC show PCE of 12.34%and 11.27%.For RCTs,the reasonably weakened crystallinity and reduced phase separation size are beneficial to improve charge transfer,reduce bimolecular recombination and trap-assisted recombination.These results indicate that the addition of a third component unit to a D-A polymer backbone provides a simple but efficient synthesis methods for high-performance OSCs materials.