Lithium benzoate doped high performance n-type diketopyrrolopyrrole based organic thin-film transistors

Abstract

We report lithium benzoate (LB) as an effective electron dopant for commonly used diketopyrrolopyrrole (DDP) based electron donor-acceptor conjugated polymers and its application in organic thin-film transistors (OTFTs). Three DPP derivative classes were considered: ambipolar, electron dominant, and hole dominant semiconducting polymers. Applying LB dopant at the contact or semiconducting layer bulk significantly improved overall n-channel performance more than 100-fold, such as electron mobility and on/off current ratio for solution -processed DPP based OTFTs compared with pristine devices. The best DPP based OTFTs with LB achieved high electron mobility (0.6 cm(2) V-1 s(-1)) with excellent operational stability. In particular, complete ambipolar transport modulation to unipolar n-type was achieved for n-channel dominant OTFTs devices.