A series of new p-type polymers, PNDT-T and PNDT-TT, with enforced coplanar structure for effective πelectron delocalization, having naphtho[2,1-b:3,4-b′]dithiophene and thiophenes as main core units, were successfully synthesized by Stille coupling reaction. The naphtho[2,1-b:3,4-b′]dithiophene unit of the polymer main chain enhances charge carrier mobility by extending πconjugation length and rigidly enforced coplanar structure. Both polymers, PNDT-T and PNDT-TT, have high thermal stability up to 250 °C with a high T g of 402 °C. On the basis of AFM and XRD results, it was found that PNDT-TT showed relatively more highly ordered intermolecular structures than did PNDT-T, with thiophene unit and high field-effect mobility, because the bithiophene unit provides crystallinity with increasing planarity and enough space for interdigitation of the long alkyl side chains for high order. These new p-type polymers PNDT-T and PNDT-TT exhibit high carrier mobilities of 0.01 and 0.076 cm 2 /(V s) and on/off ratios of 4 × 10 5 and 7 × 10 6 , respectively. The above results indicate that the plate structure with a sulfur-containing fully aromatic system, which has the upper direction extended, could enhance the thermal stability and charge transport characteristics for OTFT applications.

Organic nanofloating gate memory devices were developed based on ink-jet printed 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene thin-film transistors (TFTs) embedding gold nanoparticles. The programming/erasing operations showed that the organic memory devices exhibited good programmable memory characteristics that resulted in a gate-voltage controlled reliable threshold voltage shift of the programmed/erased states. The data retention and endurance measurements also showed the reliable nonvolatile memory properties. Solution processes were used for synthesis of the charge trapping elements and TIPS-pentacene TFTs were made by the ink-jet printing technique at low temperatures. Therefore, these processes can readily be adopted in all-printed organic memory devices on flexible substrates.

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Two novel polymeric semiconductor materials based on naphtho[2,1‐b:3,4‐b']dithiophene (NDT), PNDT‐TTT and PNDT‐TET, were designed and synthesized. These synthesized polymers were tested in bulk heterojunction solar cells as blends with the acceptor [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM). PNDT‐TTT contained tri‐thiophene units, and PNDT‐TET contained bi‐thiophene units coupled by ethylenic linkages. Comparison to the properties of PNDT‐T, which contained single thiophene units, these polymers exhibit red‐shifted absorption spectra as a result of the enhanced conjugation lengths. These effects resulted in high short circuit currents (JSC) in the organic solar cells. The PNDT‐TET‐ and PNDT‐TTT‐based devices exhibited considerably better photovoltaic performances, with power conversion efficiencies of 3.5 and 3.3%, respectively, compared to the PNDT‐T‐based device (1.3%). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4742–4751

We designed a new copolymer, PNDT-BTN with NDT and alkoxy-naphthalene units. PNDT-BDT showed an effectively lowered HOMO level by inducing non-planarity, resulting in enhanced VOC.