Stereoisomer-dependent conversion of dinaphthothienothiophene precursor films

Soluble precursor materials of organic semiconductors are employed for fabricating solution-processable thin film devices. While the so-called precursor approach has already been tried for various organic electronic devices such as transistors and solar cells, understanding of the conversion process in the film lags far behind. Here, we report that molecular aggregation of the precursor compound significantly influences the thermal conversion reaction in the film. For this study, two stereoisomers of a dinaphthothienothiophene (DNTT) precursor that are the endo- and exo-DNTT-phenylmaleimide monoadducts are focused on. The structural change during the thermal conversion process has been investigated by a combination of infrared spectroscopy and X-ray diffraction techniques. The results show that the endo-isomer is readily converted to DNTT in the film by heating, whereas the exo-isomer exhibits no reaction at all. This reaction suppression is found to be due to the self-aggregation property of the exo-isomer accompanying the intermolecular C–H⋯O interactions. This finding shows a new direction of controlling the on-surface reaction, as well as the importance of analyzing the film structure at the initial stage of the reaction

A REPORT ON THE PHYSICAL FITNESS AT NAGAOKA NATIONAL COLLEGE OF TECHNOLOGY IN 2006

本報告は、平成18年度に実施した長岡高専生のスポーツ・テストの調査結果をまとめたものである。18年度のスポーツテストの結果をみると、ほぼすべての学年で統計的に有意差が認められ、劣位な体力要素は、17年度と同様に、1)男子上体起こし、2)男子反復横とび、3)男女50m走、4)男子ハンドボール投げ、5)男子20mシャトルランの5項目と、6)男子長座体前屈が追加され、6項目であった。本校学生は、男女ともに全国平均値を上回る項目が少ない状況にあり、統計的にも明らかに劣っているといえる。また、すべての学年で有意差があった50m走の体力レベルをみると、男子は全国の13、14歳(中学2、3年生)、女子は9、10歳(小学4、5年生)レベルと同等の傾向を示す

A new schematic for poly(3-alkylthiophene) in an amorphous film studied using a novel structural index in infrared spectroscopy

The molecular structure of poly(3-alkylthiophene-2, 5-diyl) in an amorphous film reveals that the short axis of the thiophene ring is kept highly oriented parallel to the substrate, whereas the long axis along the polymer chain is largely disordered. This is unveiled by infrared p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS), achieved by analyzing the orientation angles of three mutually orthogonal vibrational modes localized on the thiophene ring with the aid of a newly developed structural index. This new analytical technique is useful irrespective of the crystallinity of the thin film. As a result, the intrinsic chemical parameters controlling the molecular orientation are understood in a unified manner, and the reason that the hexyl group gives the best results for a photovoltaic cell is also revealed

The Impact of Kinetically Restricted Structure on Thermal Conversion of Zinc Tetraphenylporphyrin Thin Films to the Triclinic and Monoclinic Phases

The powerful combination of p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS) and grazing incidence X-ray diffraction (GIXD) is applied to the structural characterization of zinc tetraphenylporphyrin (ZnTPP) in vapor-deposited films as a function of the deposition rate. The deposition rate is revealed to have an impact on the initial film structure and its conversion by thermal annealing. The pMAIRS spectra reveal that a fast deposition rate yields a kinetically restricted amorphous film of ZnTPP having a “face-on orientation”, which is readily discriminated from another “randomly oriented” amorphous film generated at a slow deposition rate. In addition, the GIXD patterns reveal that the film grown at a slow deposition rate involves a minor component of triclinic crystallites. The different initial film structure significantly influences the thermal conversion of ZnTPP films. The randomly oriented amorphous aggregates with the triclinic crystallite seeds are converted to the thermodynamically stable phase (monoclinic) via the metastable triclinic phase. The kinetically restricted structure, on the other hand, is followed by a simple thermal conversion: the molecules are directly converted to the monoclinic one rather than the triclinic one

Comprehensive Understanding of Structure-Controlling Factors of a Zinc Tetraphenylporphyrin Thin Film Using pMAIRS and GIXD Techniques

The performance of an organic electronic device is significantly influenced by the anisotropic molecular structure in the film, which has long been difficult to predict especially for a solution process. In the present study, a zinc tetraphenylporphyrin (ZnTPP) thin film prepared by a solution process was chosen to comprehensively explore the molecular-arrangement mechanism as a function of representative film-preparation parameters: solvent, film-preparation technique, and thermal annealing. The anisotropic structure was first analyzed by using a combination of infrared p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) and grazing incidence X-ray diffraction (GIXD), which readily revealed the molecular orientation and crystal structure, respectively. As a result, the real dominant factor was found to be the evaporation time of the solvent that determines the initial two different molecular arrangements, types-I and -II, while the thermal annealing was found to play an additional role of improving the molecular order. The correlation between the molecular orientation and the crystal structure was also revealed through the individual orientation analysis of the porphyrin and phenyl rings