Molecular weight dependent vertical composition profiles of PCDTBT:PC₇₁BM blends for organic photovoltaics.

ABSTRACT: We have used Soxhlet solvent purification to fractionate a broad molecular weight distribution of the polycarbazole polymer PCDTBT into three lower polydispersity molecular weight fractions. Organic photovoltaic devices were made using a blend of the fullerene acceptor PC₇₁BM with the molecular weight fractions. An average power conversion efficiency of 5.89% (peak efficiency of 6.15%) was measured for PCDTBT blend devices with a number average molecular weight of Mn = 25.5 kDa. There was significant variation between the molecular weight fractions with low (Mn = 15.0 kDa) and high (Mn = 34.9 kDa) fractions producing devices with average efficiencies of 5.02% and 3.70% respectively. Neutron reflectivity measurements on these polymer:PC₇₁BM blend layers showed that larger molecular weights

SUBMITTER: Kingsley JW 

PROVIDER: S-EPMC4055896 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature