Low Band Gap Furan‐Flanked Diketopyrrolopyrrole‐Naphthobisthiadiazole Based Conjugated Polymer/Stretchable Blend for Organic Field Effect Transistors

Abstract N‐type organic semiconducting materials that are compatible in stretchable organic field effect transistors (OFETs) still lag in performance behind that of p‐type materials. Herein, a n‐type conjugated polymer (DPPF‐NTz) is reported that comprises a furan flanked diketopyrrolopyrrole (DPPF) as a monomer and napthobisthiadiazole (NTz) as a comonomer units, respectively, in a conjugated polymer backbone. The low band gap of 1.34 eV and suitable frontier energy levels allow its utilization in OFETs as an n‐type semiconducting material. Optimized bottom‐gate top contact OFETs based on chloroform and chloroform: o ‐dichlorobenzene processed DPPF‐NTz showed a maximum electron mobility ( µ e ) of 0.00042 cm 2 V⁻¹ s⁻¹ and 0.00078 cm 2 V⁻¹ s⁻¹, respectively, in devices annealed at 150 °C. Interestingly, upon mixing the DPPF‐NTz with a stretchable polymer, polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS), yielded a stretchable semiconducting polymer composite, which displayed an enhanced µ e of 0.0024 cm 2 V⁻¹ s⁻¹ in devices annealed at 250 °C over pristine DPPF‐NTz. The improved µ e and mechanical stretchability of the DPPF‐NTz: SEBS polymer blend over pristine DPPF‐NTz polymer is examined by nano‐mechanical atomic force microscopy. The research investigation finding provides a critical insight into the structural and nano‐mechanical properties of n‐type stretchable polymer semiconductors, which are essential for the development of next‐generation wearable OFETs.