IIKUBO Satoshi



Associate Professor


2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka

Degree 【 display / non-display

  • Nagoya University -  Doctor of Science  2005.03

Biography in Kyutech 【 display / non-display

  • 2014.04

    Kyushu Institute of TechnologyGraduate School of Life Science and Systems Engineering   Department of Biological Functions Engineering   Associate Professor  


Publications (Article) 【 display / non-display

  • Suppression of charge carrier recombination in lead-free tin halide perovskite via lewis base post-treatment

    Kamarudin M., Hirotani D., Wang Z., Hamada K., Nishimura K., Shen Q., Toyoda T., Iikubo S., Minemoto T., Yoshino K., Hayase S.

    Journal of Physical Chemistry Letters    10 ( 17 ) 5277 - 5283   2019.09  [Refereed]

     View Summary

    Copyright © 2019 American Chemical Society. Lead-free tin perovskite solar cells (PSCs) show the most promise to replace the more toxic lead-based perovskite solar cells. However, the efficiency is significantly less than that of lead-based PSCs as a result of low open-circuit voltage. This is due to the tendency of Sn2+ to oxidize into Sn4+ in the presence of air together with the formation of defects and traps caused by the fast crystallization of tin perovskite materials. Here, post-treatment of the tin perovskite layer with edamine Lewis base to suppress the recombination reaction in tin halide PSCs results in efficiencies higher than 10%, which is the highest reported efficiency to date for pure tin halide PSCs. The X-ray photoelectron spectroscopy data suggest that the recombination reaction originates from the nonstoichiometric Sn:I ratio rather than the Sn4+:Sn2+ ratio. The amine group in edamine bonded the undercoordinated tin, passivating the dangling bonds and defects, resulting in suppressed charge carrier recombination.

    DOI Scopus

  • Relationship between Lattice Strain and Efficiency for Sn-Perovskite Solar Cells

    Nishimura K., Hirotani D., Kamarudin M., Shen Q., Toyoda T., Iikubo S., Minemoto T., Yoshino K., Hayase S.

    ACS Applied Materials and Interfaces    11 ( 34 ) 31105 - 31110   2019.08  [Refereed]

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    Copyright © 2019 American Chemical Society. In the composition of Q0.1(FA0.75MA0.25)0.9SnI3, Q is replaced with Na+, K+, Cs+, ethylammonium+ (EA+), and butylammonium+ (BA+), respectively, and the relationship between actually measured lattice strain and photovoltaic performances is discussed. The lattice strain evaluated by the Williamson-hall plot of X-ray diffraction data decreased as the tolerance factor was close to one. The efficiency of the Sn-perovskite solar cell was enhanced as the lattice strain decreased. Among them, EA0.1(FA0.75MA0.25)0.9SnI3 having lowest lattice strain gave the best result of 5.41%. Because the carrier mobility increased with a decrease in the lattice strain, these lattice strains would disturb carrier mobility and decrease the solar cell efficiency. Finally, the results that the efficiency of the SnGe-perovskite solar cells was gradually enhanced from 6.42 to 7.60% during storage, was explained by the lattice strain relaxation during the storage.

    DOI Scopus

  • First-Principles Study of Chemical Driving Force for Face Centered Cubic to Hexagonal Close Packed Martensitic Transformation in Hydrogen-Charged Iron

      50 ( 7 ) 3019 - 3023   2019.07  [Refereed]

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    © 2019, The Minerals, Metals & Materials Society and ASM International. This study uses first-principles calculations to investigate the effect of hydrogen on the chemical driving force of the transformation of iron from the face centered cubic (FCC) to hexagonal close packed (HCP) phase. The minimum energy path from FCC to HCP phases shows that FCC becomes stable with increasing hydrogen content. Furthermore, the energy difference between the FCC and HCP phases is observed to be smaller in Fe2H than in Fe throughout the temperature region. These results clearly explain the observed anomalous suppression of the martensitic transformation in the hydrogen-charged steel.

    DOI Scopus

  • Experimental and Theoretical Elucidation of Electrochemical CO <inf>2</inf> Reduction on an Electrodeposited Cu <inf>3</inf> Sn Alloy

      123 ( 5 ) 3004 - 3010   2019.02  [Refereed]

     View Summary

    © 2019 American Chemical Society. The reaction selectivity of an electrode catalyst can be modulated by regulating its crystal structure, and the modified electrode may show different CO 2 reduction selectivity from that of its constituent metal. In this study, we investigated the mechanisms of the electrochemical CO 2 reduction on an electrodeposited Cu 3 Sn alloy by experimental and theoretical analyses. The electrodeposited Cu 3 Sn alloy electrode showed selectivity for CO production at all the applied potentials, and HCOOH production increased with an increase in the applied potential. In particular, hydrocarbon generation was well suppressed on Cu 3 Sn(002). To understand this selectivity change in electrochemical CO 2 reduction, we conducted density functional theory calculations for the reaction on the Cu 3 Sn(002) surface. According to the theoretical analysis, the Cu sites in Cu 3 Sn(002) contributed more to the stabilization of H∗, COOH∗, and CO∗ as compared with the Sn sites. Furthermore, the results indicated that Cu 3 Sn(002) decreased the surface coverage of reaction intermediates such as H∗, COOH∗, and CO∗. We believe that these effects promoted CO∗ desorption while suppressing H 2 generation, CO∗ protonation, and C-C bond formation. The results also suggested that the surface Sn concentration significantly affected the reaction selectivity for HCOOH production from CO 2 .

    DOI Scopus

  • Pb-free Sn perovskite solar cells doped with samarium iodide

      48 ( 8 ) 836 - 839   2019.01  [Refereed]

     View Summary

    © 2019 The Chemical Society of Japan. The efficiency of Sn-perovskite solar (Sn-PVK) cells was enhanced by adding 1% Samarium iodide (SmI2). Increase in Jsc and FF is associated with the enhancement of efficiency and and explained by lower series resistance. SmI2 is known as a strong reducing agent and is oxidized to Sm3+ by reducing a substrate. By adding 1 and 5% SmI2, the carrier concentration of Sn-perovskite layer due to the presence of Sn4+ was decreased from 4.8 © 1022/cm3 to 1.2 © 1019/cm3 and 6.1 © 1018/cm3 respectively, because of the suppression of the oxidation from Sn2+ to Sn4+ by the strong reducing properties of SmI2. The low charge carrier concentration is also associated with the enhanced solar cell efficiency.

    DOI Scopus CiNii

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Conference Prsentations (Oral, Poster) 【 display / non-display

  • Lattice dynamics of all-inorganic perovskite CsSnX 3 (X = Cl, Br, and I): A first-principles study

    Shoya Kawano,Satoshi Iikubo

    PSCO-2019  2019.09  -  2019.09  PSCO

  • Effect of substitution on the stability in Tin based Perovskite: First-Principles study

    Kumiko Yamamoto,Satoshi Iikubo

    PSCO-2019  2019.09  -  2019.09  PSCO

  • 進化的アルゴリズムによる有機無機ペロブスカイト化合物の安定構造探索と熱電特性

    山本 久美子,飯久保 智

    2019年第80回応用物理学会秋季学術講演会  2019.09  -  2019.09  応用物理学会

  • 鉛フリー有機無機ペロブスカイトの電子状態計算

    井手 敦子,山本 久美子,奥村 崚,飯久保 智,早瀬 修二

    2019年第80回応用物理学会秋季学術講演会  2019.09  -  2019.09  応用物理学会

  • 2次元構造を持つハロゲン化ペロブスカイトの熱電特性計算

    成田 昴宇,山本 久美子,飯久保 智

    2019年第80回応用物理学会秋季学術講演会  2019.09  -  2019.09  応用物理学会

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