Growth Domain Size of Conjugated Polymer Film by Kinetic Control Metastable States for High-Performance N-Type Field-Effect Transistors

Abstract

Organic field effect transistors (OFETs) have attracted much interest for future electronics because they can have flexibility with processing from solution at low temperature. Recently many researches make an attempt to control the film morphology which directly correlated to the charge transporting ability of conjugated polymers. In this work, we demonstrate optimized poly{[N,N’-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5’-(2,2’-bithiophene)} (P(NDI2OD-T2)) film morphologies, which are obtained by precisely regulating the solidification rate in the metastable state using a novel simple method. The kinetic control in the metastable state brings about dramatic morphological changes in both polymer domain sizes and molecular packing structures. The optimized P(NDI2OD-T2) films provide significantly increased electron mobilities up to 3.99 cm2 V-1 s-1, which is the impressive improvement in performance by nearly 100-fold as compared to conventional spin-coated devices. The observation of low activation energy according to the temperature-dependent behavior in optimized thin films can support the achievement of high electron mobilities of semiconducting polymers.