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A thin film of thiophene block copolymer composed of 3-dodecylthiophene and 3-benzenesulfonato–thiophene was fabricated by using the friction-transfer method. The benzenesulfonato moiety was transformed by heating to the corresponding sulfonic acid, which induced self-doping. The obtained friction-transfer film showed different morphology from the related cast film. It was also revealed that the film indicated anisotropy parallel/perpendicular toward the drawing direction, which induced absorption dichroism and anisotropy of electric conductivity. [ABSTRACT FROM AUTHOR]

1D organic semiconductor nanostructures have attracted considerable attention; however, only a few studies are conducted on p–n junction organic semiconductor 1D nanostructures. Herein, p‐ and n‐type and p–n junction phthalocyanine (Pc) nanorods are grown in the out‐of‐plane direction of a substrate via vacuum deposition using typical organic semiconductors with copper phthalocyanine (CuPc) as the p‐type semiconductor and copper octafluorophthalocyanine (F8CuPc) and copper hexadecafluorophthalocyanine (F16CuPc) as the n‐type semiconductors. p–n junction Pc nanorods are fabricated via the continuous deposition of F8CuPc and F16CuPc onto CuPc nanorods. Fourier‐transform infrared spectroscopy reveals that the Pc molecules in the nanorods are perpendicularly aligned, with their molecular planes oriented toward the longitudinal direction of the nanorods. The local current–voltage properties of the nanorods are measured using conductive atomic force microscopy. The hole mobility in the CuPc nanorods is 10 times higher than that in the CuPc thin films. The p–n junction properties of F8CuPc/CuPc nanorods are evaluated. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric devices with poly (vinylidene fluoride–trifluoroethylene) thin films were fabricated, and directly monitoring of the heart state and piezoelectric power generation were investigated using the pulsating 3D heart model. By attaching the flexible piezoelectric devices to the 3D heart model, the piezoelectric responses corresponding to the pulsation of the right and left ventricles were observed and reflected the status of heart. The maximum output voltage was obtained in the front of the right ventricle of the heart model. The output energy, which caused from piezoelectric effect, improved linearly with the increase of the device area, and was estimated to be approximately 8 nJ mm−2 per heartbeat. [ABSTRACT FROM AUTHOR]

Perpendicularly oriented vinylidene fluoride oligomer thin films with six molecular layers were poled during vacuum evaporation (in situ poling) using a micro-gapped comb-like electrode, and their pyroelectric characteristics were investigated. The extent of polarization achieved with in situ poling performed by applying a low electric field (7.7 MV m−1) is the same as that achieved by conventional post-poling with the application of a high electric field (>100 MV m−1). Despite using a film with a few molecular layers, the in situ poled sensor showed pyroelectric response without the use of an infrared ray absorption layer; voltage sensitivity of 198 V W−1 was obtained, which is much higher than that of the post-poled sensor (∼16 V W−1). The improvement in sensitivity is attributed to the amount of charge injected during the poling treatment. [ABSTRACT FROM AUTHOR]

Quantitative analyses of photodegradation for three fluorene-based photovoltaic polymers, poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (APFO3), polyfluorene (PFO), and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), were conducted to understand the molecular origin of photostability for polymers. The Fourier transform infrared spectra of the polymer thin films varied with irradiating white light at 100 mW cm−2 irrespective of their molecular architectures. The absorption peaks corresponding to alkyl side chains in the fluorene unit decreased, whereas those for polymers that did not comprise carbonyl groups increased. This spectral variation indicates that alkyl side chains in the fluorene unit decompose when the molecular structure of fluorene changes to that of fluorenone. The reaction rate constant of the formation of C=O bonds for APFO3 was 1.64 × 10−5 s−1, lower than those for PFO (7.59 × 10−5 s−1) and F8BT (2.64 × 10−5 s−1), under light irradiation at 30 °C. The photostability of the polymers was improved by designing a donor–acceptor type molecular architecture incorporating photostable electron-deficient benzothiadiazole units with photo-unstable fluorene units. [ABSTRACT FROM AUTHOR]