High‐Performance n‐Type OFETs Enabled by Pyridine‐Substituted Diketopyrrolopyrrole Organic Semiconductor and Elastomer Stretchable Blends

Abstract The contemporary research on developing n‐type organic semiconducting materials (OSMs) has great significance for stretchable organic field‐effect transistors (OFETs). Two n‐type OSMs (DPPPy‐C10‐TN and DPPPy‐C‐Si‐TN) based on alkyl/siloxane‐substituted pyridine flanked diketopyrrolopyrrole (DPPPy) end capped with thienyl naphthalimide (TN) are reported. Although DPPPy‐C10‐TN and DPPPy‐C‐Si‐TN show similar optical and electrochemical properties, they show a significant variation in their morphological and crystalline properties in pristine form or within an elastic polymer (polystyrene‐ block ‐poly(ethylene‐ ran ‐butylene)‐ block ‐polystyrene; SEBS) matrix, which further reflects on their electrical properties. Interestingly, bottom‐gate top‐contact OFETs of as‐cast pristine DPPPy‐C10‐TN show a higher electron mobility ( µ e = 0.103 cm 2  V −1 s −1 ) than DPPPy‐C‐Si‐TN ( µ e = 0.0145 cm 2  V −1 s −1 ), underscoring the influence of alkyl substitution on charge transport efficiency. By contrast, stretchable DPPPy‐C‐Si‐TN:SEBS blend shows a significantly higher electron mobility ( µ e = 0.322 cm 2  V −1 s −1 ) in comparison to the DPPPy‐C10‐TN:SEBS blend ( µ e = 0.00196 cm 2  V −1 s −1 ). To the best of the authors’ knowledge, this is the first successful report about a high µ e value reported for a DPPPy‐based n‐type small molecule stretchable OSM blend in OFETs and provides new insights into the design and processing principles of small molecule based OSMs for flexible electronics.