Efficient N-Doping in Organic Semiconductors by Novel Approaches and Materials Design

In this presentation we will report new strategies to efficiently n-doped organic semiconductor films. Thus, starting from initial work investigating molecular n-doping of naphthalenediimide (NDI) and isomeric benzothiadiazole (isoBT) based polymers we explored how variations in polymer backbone composition, regiochemistry, thin-film processing, and doping affect major film morphology and charge transport characteristics in transistor and diode architectures. For instance, we showed that NDI-(TVT)_x(TET)_y [x+y=100%; TVT = thienyl-CH=CH-thienyl; TET = thienyl-CH₂CH₂-thienyl] charge transport in transistor has a unique dependence on the x,y values. Thus, we explored how charge transport is affected in diodes as well as how NDI-(TVT)_x(TET)_y (polymer acceptor) + polymer donor solar cells perform. Finally, we recently discovered new approaches to enhance doping efficiency and conductivity via 1, tuning film morphology by favoring molecule dopant penetration and, 2, using catalysts that promote the semiconductor+dopant reaction. The latter strategy enables excellent doping efficiencies and conductivities for several organic semiconductors.