TY - JOUR
T1 - The growth mechanism and characterization of few-layer diphenyl dinaphthothienothiophene films prepared by vacuum deposition
AU - Hattori, Yoshiaki
AU - Kimura, Yoshinari
AU - Yoshioka, Takumi
AU - Kitamura, Masatoshi
N1 - Funding Information:
This work was supported by the Leading Initiative for Excellent Young Researcher (LEADER) of the Ministry of Education, Culture, Sports, Science and Technology in Japan and JSPS KAKENHI Grant Numbers 19H02171, 19K15048 . The authors would like to thank Nippon Kayaku Co., Ltd. for supplying DPh-DNTT.
Funding Information:
Moreover, the growth process of the second layer was also investigated. Fig. 3 shows the optical dark-field microscopy and AFM images of the films deposited at 160 °C on the substrates treated with UV-O3 Fig. 3(a) and O2 plasma Fig. 3(b), with a nominal thickness of 4.8 and 3.6 nm, respectively. The AFM image corresponds to the dotted area in Fig. 3(b). The height diagrams of the film for the three dotted lines (A-A′, B–B′, C–C′) in the AFM image were indicated on the AFM image, respectively. Based on the evolution of the 2D island growth for the first layer, two 2D islands coalesced into one island. Some coalesced regions can be seen smoothly connected in Fig. 3(c) at the AFM resolution. In addition, nucleation of a second layer can be observed as a flat 2D island deposited on the first layer before completion of the first layer. When focusing on the number of nuclei for the second layer, we concluded that N for the second layer is smaller than N for the first layer. Note that the elongated parts in both images are DPh-DNTT formations with a height of more than 80 nm, much taller than the remaining area. These formations may be tall walls, also observed in previous studies [12,18]. The formations tend to appear during the growth of the second layer. To support these observations, it seems that the tall wall in the AFM image (C–C′) elongates from the second layer part (B–B’).This work was supported by the Leading Initiative for Excellent Young Researcher (LEADER) of the Ministry of Education, Culture, Sports, Science and Technology in Japan and JSPS KAKENHI Grant Numbers 19H02171, 19K15048. The authors would like to thank Nippon Kayaku Co. Ltd. for supplying DPh-DNTT.
Publisher Copyright:
© 2019
PY - 2019/11
Y1 - 2019/11
N2 - The growth mechanism of 2,9-diphenyl-dinaphtho [2,3-b:2′,3′-f]thieno [3,2-b]thiophene (DPh-DNTT) thin-films prepared by vacuum deposition was investigated based on the morphological crystallinity of the obtained films. In addition to atomic force microscopy, which is commonly used for imaging surface morphology, optical microscopy was also positively used for the same purpose. The technique allows the quick and easy evaluation of thin films. The optical microscopy images show that DPh-DNTT films grew according to a layer-by-layer growth mode. Each layer grew as flat two-dimensional (2D) islands with a thickness of about 2.3 nm, where DPh-DNTT molecules stand almost vertically on the substrate. The height difference between layers provided a color contrast in these images, which visualizes the initial 2D island on the Si substrate with thermally grown SiO2 and fractal-shape 2D islands on top surface. By using the method, a monolayer of isolated and round 2D islands, with a diameter of approximately 4 μm, formed at a high substrate temperature on a SiO2 surface that had been previously treated with O2 plasma or UV-O3. The presence of a DPh-DNTT layer on the substrate was also confirmed by micro-Raman measurement.
AB - The growth mechanism of 2,9-diphenyl-dinaphtho [2,3-b:2′,3′-f]thieno [3,2-b]thiophene (DPh-DNTT) thin-films prepared by vacuum deposition was investigated based on the morphological crystallinity of the obtained films. In addition to atomic force microscopy, which is commonly used for imaging surface morphology, optical microscopy was also positively used for the same purpose. The technique allows the quick and easy evaluation of thin films. The optical microscopy images show that DPh-DNTT films grew according to a layer-by-layer growth mode. Each layer grew as flat two-dimensional (2D) islands with a thickness of about 2.3 nm, where DPh-DNTT molecules stand almost vertically on the substrate. The height difference between layers provided a color contrast in these images, which visualizes the initial 2D island on the Si substrate with thermally grown SiO2 and fractal-shape 2D islands on top surface. By using the method, a monolayer of isolated and round 2D islands, with a diameter of approximately 4 μm, formed at a high substrate temperature on a SiO2 surface that had been previously treated with O2 plasma or UV-O3. The presence of a DPh-DNTT layer on the substrate was also confirmed by micro-Raman measurement.
KW - 2D island
KW - DPh-DNTT
KW - Fractal
KW - Layer-by-layer growth
KW - Vacuum deposition
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U2 - 10.1016/j.orgel.2019.07.014
DO - 10.1016/j.orgel.2019.07.014
M3 - Article
AN - SCOPUS:85068850554
VL - 74
SP - 245
EP - 250
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
SN - 1566-1199
ER -