End Capping Does Matter: Enhanced Order and Charge Transport in Conjugated Donor–Acceptor Polymers

Optimized microstructure through control of both intra- and intermolecular interactions in organic semiconductors is critical for enhancing and optimizing charge transport for the realization of next-generation low-cost, mechanically flexible, and easy to process high performance, organic field effect transistors (OFETs). Herein, we report donor–acceptor alternating copolymers of dithienogermole (DTG) with 2,1,3-benzothiadiazole (BTD) and probe the importance of end groups on the control of molecular order and microstructure as it relates to the enhancement of charge carrier transport. Partial end-capping reactions, confirmed by 1H NMR and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analyses, on the DTG–BTD copolymer provided significant improvement in grazing incidence wide angle X-Ray scattering (GIWAXS) determined polymer ordering in thin films. Consequently, OFETs exhibited charge-carrier mobilities up to 0.60 cm2/(Vs) for the end-capped copolymer, which are an order of ma...