Benzyl viologen radical cation: an effective n-dopant for poly(perylenediimide-bithiophene)

n-Dopant is one of the cornerstones for the development of n-doped conducting polymers which has huge potential in applications like polymer thermoelectrics and as an electron-transporting layer in solar cells. Here, we demonstrate the use of benzyl viologen radical cation (BV˙+) as an effective n-dopant for poly[N,N′-bis(2-octyldodecyl)-3,4,9,10-perylenediimide-1,6/7-diyl]-alt-5,5′-(2,2′-bithiophene) (pPDI-2T) and measured its thermoelectric performance for the first time. The charge and ion transport of the BV˙+-doped pPDI-2T films were also characterized. The BV˙+-doped pPDI-2T films showed minimum contact resistance and very good electrical stability in the glovebox, with stability of more than 2 weeks at room temperature and more than 24 hours at 100 °C.