One‐Step Sixfold Cyanation of Benzothiadiazole Acceptor Units for Air‐Stable High‐Performance n‐Type Organic Field‐Effect Transistors
Panagiota Kafourou, Byoungwook Park, Joel Luke, Luxi Tan, Julianna Panidi, Florian Glöcklhofer, Jehan Kim, Thomas D. Anthopoulos, Ji‐Seon Kim, Kwanghee Lee, Sooncheol Kwon, Martin Heeney
Abstract
Abstract Reported here is a new high electron affinity acceptor end group for organic semiconductors, 2,1,3‐benzothiadiazole‐4,5,6‐tricarbonitrile (TCNBT). An n‐type organic semiconductor with an indacenodithiophene (IDT) core and TCNBT end groups was synthesized by a sixfold nucleophilic substitution with cyanide on a fluorinated precursor, itself prepared by a direct arylation approach. This one‐step chemical modification significantly impacted the molecular properties: the fluorinated precursor, TFBT IDT, a poor ambipolar semiconductor, was converted into TCNBT IDT, a good n‐type semiconductor. The electron‐deficient end group TCNBT dramatically decreased the energy of the highest occupied and lowest unoccupied molecular orbitals (HOMO/LUMO) compared to the fluorinated analogue and improved the molecular orientation when utilized in n‐type organic field‐effect transistors (OFETs). Solution‐processed OFETs based on TCNBT IDT exhibited a charge‐carrier mobility of up to μ e ≈0.15 cm 2 V −1 s −1 with excellent ambient stability for 100 hours, highlighting the benefits of the cyanated end group and the synthetic approach.