飯久保 智 (イイクボ サトシ)

IIKUBO Satoshi

写真a

職名

准教授

研究室住所

福岡県北九州市若松区ひびきの2-4

取得学位 【 表示 / 非表示

  • 名古屋大学 -  博士(理学)  2005年03月

学内職務経歴 【 表示 / 非表示

  • 2014年04月
    -
    継続中

    九州工業大学   大学院生命体工学研究科   生体機能応用工学専攻   准教授  

 

論文 【 表示 / 非表示

  • Structural stability and electronic property evaluations for different Bi<inf>2</inf>Te<inf>3</inf> (0 0 1) termination surfaces

    Morimoto M., Kawano S., Miyazaki K., Iikubo S.

    Applied Surface Science    525   2020年09月  [査読有り]

     概要を見る

    © 2020 Elsevier B.V. For thermoelectric materials, the figure of merit depends on the nanostructure, morphology, element doping, and the structure of the interface with other materials. Control of this interface is important in relation to a wide range of thermoelectric material designs such as in organic–inorganic hybrid compounds. Therefore, we evaluated the ease of forming various Bi2Te3 (0 0 1) termination surfaces using formation energy and calculation of phonon dispersion after structure optimization; TeI-1 and TeII terminations exhibited static and dynamic stabilities within various termination structures. In density-of-state and charge-distribution calculations, the TeII termination form exhibited distinctive electronic states around the Fermi energy that originated from the exposed Te atoms; therefore, it is suggested that efficient carrier transfer shall occur at the interface between a TeII surface and another material.

    DOI Scopus

  • Lead-free tin-halide perovskite solar cells with 13% efficiency

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

    Nano Energy    74   2020年08月  [査読有り]

     概要を見る

    © 2020 Elsevier Ltd Despite the similarities of the optoelectronic properties between tin halide and lead halide perovskites, the performance of tin perovskite solar cells (PSCs) is still far below that of lead PSCs with highest reported efficiency to date of around 10%. This is due to the chemical instability of tin halide perovskite crystals and the energy band levels mismatch between the perovskite and charge transport layers. In this work, tin halide PSCs with efficiency of more than 13% has been fabricated by regulating the A site cation to achieve a tolerance factor of nearly 1. The partial substitution of formamidinium cation with ethylammonium cation affords a more stable tin perovskite crystal and at the same time suppresses the trap density by as much as 1 order of magnitude. Furthermore, the more favourable energy levels of the EA-substituted tin perovskites enhanced the charge extraction process into the charge transport layers and thus reducing the charge carrier recombination. This work provides a proof that tin-halide PSCs has the potential to compete with more toxic lead-based PSCs, and hopefully will pave the future direction for fabricating more efficient and stable lead-free PSCs.

    DOI Scopus

  • First-principles study of thermoelectric properties of mixed iodide perovskite Cs(B,B′)I<inf>3</inf> (B, B′ = Ge, Sn, and Pb)

    Yamamoto K., Narita G., Yamasaki J., Iikubo S.

    Journal of Physics and Chemistry of Solids    140   2020年05月  [査読有り]

     概要を見る

    © 2020 Elsevier Ltd The thermoelectric properties of the mixed iodide perovskites Cs(B,B′)I3 (B, B′ = Ge, Sn, and Pb), which are related to the well-known organic–inorganic hybrid perovskite used in solar cells, were studied using first-principles calculation. We evaluated the thermoelectric properties of stable partially substituted structures, which were explored by applying a cluster expansion method in our previous work based on the Boltzmann transport equation. The calculated figure of merit, ZT, is larger for N-type systems than for P-type systems. The gradient of the density of states (DOS) at the conduction band edge is steep for all the compositions. This steep conduction edge results in large Seebeck coefficients in N-type systems. Excellent thermoelectric performance can be expected in N-type systems. Among the lead-free compounds, a Cs(Ge,Sn)I3 solid solution with a high germanium content is a possible candidate for a high-ZT material. It was observed that ZT and the Seebeck coefficient increase with increasing gradient of the DOS near the Fermi energy. In addition, ZT and the Seebeck coefficient increase as the band gap increases, which is remarkable in a P-type system. This result indicates a close relationship among the ZT, Seebeck coefficient, and band gap in P-type systems.

    DOI Scopus

  • Enhanced Device Performance with Passivation of the TiO<inf>2</inf> Surface Using a Carboxylic Acid Fullerene Monolayer for a SnPb Perovskite Solar Cell with a Normal Planar Structure

    Hamada K., Tanaka R., Kamarudin M.A., Shen Q., Iikubo S., Minemoto T., Yoshino K., Toyoda T., Ma T., Kang D.W., Hayase S.

    ACS Applied Materials and Interfaces    12 ( 15 ) 17776 - 17782   2020年04月  [査読有り]

     概要を見る

    Copyright © 2020 American Chemical Society. Research on tin-lead (SnPb) perovskite solar cells (PSCs) has gained popularity in recent years because of their low band gap, which could be applied to tandem solar cells. However, most of the work is based on inverted PSCs using PEDOT:PSS as the hole-transport layer as normal-structure PSCs show lower efficiency. In this work, the reason behind the low efficiency of normal-structure SnPb PSCs is elucidated and surface passivation has been tested as a method to overcome the problem. In the case of normal PSCs, at the interface between the titania layer and SnPb perovskite, there are many carrier traps observed originating from Ti-O-Sn bonds. In order to avoid the direct contact between titania and the SnPb perovskite layer, the titania surface is passivated with carboxylic acid C60 resulting in an efficiency increase from 5.14 to 7.91%. This will provide a direction of enhancing the efficiency of the normal-structure SnPb PSCs through heterojunction engineering.

    DOI Scopus

  • Theoretical analysis of band alignment at back junction in Sn–Ge perovskite solar cells with inverted p-i-n structure

    Minemoto T., Kawano Y., Nishimura T., Shen Q., Yoshino K., Iikubo S., Hayase S., Chantana J.

    Solar Energy Materials and Solar Cells    206   2020年03月  [査読有り]

     概要を見る

    © 2019 Elsevier B.V. Pb-free perovskite solar cells are investigated to eliminate the toxic Pb. However, the Pb-free perovskite solar cell with power conversion efficiency (PCE) of below 9% has been reported mainly because of low open circuit voltage (VOC). In this contribution, the theoretical analysis of the Pb-free perovskite solar cells with an inverted p-i-n planar structure, where the perovskite is FA0.75MA0.25Sn0.95Ge0.05I3 (Sn–Ge perovskite), was therefore conducted using device simulation. It is disclosed that VOC is positively affected by built-in potential across the perovskite absorber (Vbi). The Vbi is primarily governed by conduction band minimum (EC) of electron transporting layer (ETL) and/or work function of back contact (Φ_BC), where they should not be deeper (lower) than the EC (−3.67 eV) of the Sn–Ge perovskite absorber to avoid the Vbi loss for high VOC. Consequently, the ETL and BC materials in the Sn–Ge perovskite solar cells should be appropriately chosen for both suitable conduction band offset of perovskite and ETL, as well as the difference of the EC of perovskite and Φ_BC, thus developing the device structure and increasing Vbi and VOC for the improved PCE.

    DOI Scopus

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口頭発表・ポスター発表等 【 表示 / 非表示

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

    Shoya Kawano,Satoshi Iikubo

    PSCO-2019  2019年09月  -  2019年09月    PSCO

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

    Kumiko Yamamoto,Satoshi Iikubo

    PSCO-2019  2019年09月  -  2019年09月    PSCO

  • 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年09月  -  2019年09月    応用物理学会

  • 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年09月  -  2019年09月    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年09月  -  2019年09月    応用物理学会

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科研費獲得実績 【 表示 / 非表示

  • 初期構造に依存しない安定構造探索法の開発

    若手研究(B)

    研究期間:  2013年04月  -  2016年03月

    研究課題番号:  25820324

  • 実空間局所磁気構造解析法によるスピネル化合物の異常磁気相関の解明

    若手研究(B)

    研究期間:  2009年04月  -  2011年03月

    研究課題番号:  21740239

 

担当授業科目 【 表示 / 非表示

  • 2019年度  環境材料設計

  • 2019年度  計算材料学Ⅰ

  • 2018年度  環境材料設計

  • 2018年度  計算材料学Ⅰ

  • 2017年度  計算材料学Ⅰ

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