A convenient method for C-S cross-coupling of aryl bromides with various thiols has been developed that involves the use of a 1,1¢-bis(diphenylphosphino)ferrocene (DPPF)-ligated palladium complex with N,N-diisopropylethylamine (DIPEA) as the base. This coupling is tolerant of a wide range of functional groups, including hydroxy, amino, cyano, nitro, formyl, and carboxyl groups.

A long-term air-stable n-type organic semiconductor, 2,5-difluoro-1,4-phenylene-bis{2-[4-(trifluoromethyl)phenyl]acrylonitrile}, was synthesized by a high-yield simple procedure of Knoevenagel condensation with aldehyde and acetonitrile derivatives. A fabricated organic thin-film transistor (OTFT) using this compound exhibited good n-channel OTFT properties with a high electron mobility of 0.17 cm(2) V(-1) s(-1) and an on/off current ratio of 10(6) under both vacuum and ambient air operation. After storage in ambient air for 1 year, a stored n-channel OTFT still shows good n-channel OTFT performance with little degradation in ambient air operation.

A novel n-type organic semiconductor, cyano-substituted distyrylbenzene derivative, 1,4-bis{2-[4-(trifluoromethyl)phenyl]acrylonitorile}benzene, was synthesized by Knoevenagel condensation with aldehyde and acetonitrile derivatives. Fabricated thin-film transistors (TFTs) exhibited high electron field-effect mobility of 10 À2 -10 À1 cm 2 V À1 s À1 , on/off current ratio of 6 Â 10 5 . Hysteresis-free n-type transport characteristics observed in this device promises a steady operation of organic logic circuit. Almost same TFT characteristic was observed even after 1 month storage in ambient condition. The findings indicate that the material has a good resistance to atmospheric oxidants.

π‐Conjugated polymers, PTOTBT, PTEHTBT, and PTt‐BTBT, composed of benzothiadiazole as an electron accepting unit and terthiophene as an electron donating unit in the backbone were prepared. PTOTBT, PTEHTBT, and PTt‐BTBT contained side chain groups of n‐octyl, 2‐ethylhexyl, and t‐butyl groups, respectively. Solubility, optical and thermal properties of the polymers showed strong dependences on their side chain groups. PTEHTBT having 2‐ethylhexyl groups in the side chain exhibited absorption maximum (λmax) at longer wavelength (565 nm) than PTOTBT (534 nm) and PTt‐BTBT (495 nm). PTOTBT showed higher thermal stability than the others. The prepared polymers were employed to polymer solar cells (PSCs) with a configuration of ITO/PEDOT‐PSS/polymer: PC61BH/LiF/Al. Power conversion efficiency of the PSC‐based on PTEHTBT was 1.32%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Soluble polythiophenes bearing strong electron withdrawing groups, dicyanoethenyl [ACH¼ ¼C(CN) 2 ] (PTDCN) and cyano-methoxycarbonylethenyl [ACH¼ ¼C(CO 2 Me)CN] (PTCNME), in the side chains have been prepared. Optical band gaps calculated from onset absorption were 1.70 eV and 1.73 eV for PTDCN and PTCNME, respectively. Highest occupied molecular orbital energy levels measured with a surface analyzer (AC-2) were À5.53 eV and À5.29 eV for PTDCN and PTCNME, respectively, which were much lower than that of poly(3-hexylthiophene) (À4.81 eV). To investigate photovoltaic properties, bulk heterojunction polymer solar cells based on PTDCN and PTCNME were fabricated with a structure of ITO/ PEDOT:PSS/active layer/LiF/Al, where the active layer was a blend film of polymer and [6,6]-phenyl C 61 butyric acid hexyl ester (PC 61 BH). Solar cell parameters were estimated from current density-voltage (J-V) characteristics under the illumination of AM1.5 at 100 mW/cm 2 . The solar cell based on the blend film of PTCNME:PC 61 BH (1:1) showed power conversion efficiency (PCE) of 0.72% together with the open current voltage (V oc ) of 0.61 V, the short current density (J sc ) of 3.90 mA/cm 2 , and the fill factor of 30.3%. The PCE of a solar cell fabricated from PTDCN in a similar way was 0.56%. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [234][235][236][237][238][239][240][241] 2011