Indeno[1,2-b]thiophene End-capped Perylene Diimide: Should the 1,6-Regioisomers be systematically considered as a byproduct?

Usually considered as a byproduct, the 1,6- dibrominated PDI has rarely been functionalized for the preparation of electro-active conjugated molecules, particularly in the field of organic photovoltaics. In light of the literature, one can ask oneself: Does a 1,7 -isomer based functional molecule systematically perform better than its 1,6 -analogue? To answer this question, we report herein the synthesis and direct comparison of two indeno[1,2- b ]thiophene (IDT) end-capped perylene diimide regioisomers (PDI) ( 1,6 and 1,7 ) used as non-fullerene acceptors in organic solar cells. It turned out that in our case, ie , when blended with the well-known PTB7-Th donor polymer, higher performance was reached for devices made with the 1,6 -analogue.