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

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 (mu e = 0.103 cm2 V-1 s-1) than DPPPy-C-Si-TN (mu e = 0.0145 cm2 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 (mu e = 0.322 cm2 V-1 s-1) in comparison to the DPPPy-C10-TN:SEBS blend (mu e = 0.00196 cm2 V-1 s-1). To the best of the authors' knowledge, this is the first successful report about a high mu 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.