4-7-bis(5-bromo-4-2-octyldodecylthiophen-2-yl)-5,6-difluorobenzo[c][1,2,5]-thiadiazole, also known as PCE11 monomer (CAS number 1504626-07-6), is a monomer with difluoro attached on benzothiadiazole unit which gives greater electron withdrawn ability to further modify the energy gap of the polymer semiconductor materials. Polymerized with 5,5'-bis(trimethylstannyl)-2,2'-thiophene, PCE11 monomer yields the polymer PffBT4T-2OD (PCE11) which has a power conversion efficiency over 10%.