2019 Fiscal Year Final Research Report
Quantification of lattice defect density in semiconductors using emissive ruthenium complexes as probes
| Project/Area Number |
17K19169
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Inorganic materials chemistry, Energy-related chemistry, and related fields
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
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| Project Period (FY) |
2017-06-30 – 2020-03-31
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| Keywords | 光触媒 / 水分解 / 人工光合成 |
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| Outline of Final Research Achievements |
SrTiO3-δ having controlled oxygen defect density (i.e., electron density) was synthesized, and the photocatalytic activities for hydrogen and oxygen evolution were found to be increased linearly with increasing the electron density from ~10E17 cm-3. Trapping effect of photoexcited charge carriers at the surface of SrTiO3-δ was investigated by measuring emission lifetimes of ruthenium complexes adsorbed on the SrTiO3-δ surface. The result showed that increasing the oxygen defect density in SrTiO3-δ could suppress electron injection from the excited state of the ruthenium complex. Using several ruthenium complexes that had different excited state oxidation potentials, it was possible to measure the energy level of defects existing in the semiconductor.
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| Free Research Field |
エネルギー変換型光触媒
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| Academic Significance and Societal Importance of the Research Achievements |
半導体中の格子欠陥は、光励起電子と正孔の再結合中心として働くことが経験的に知られており、欠陥密度の低減は高性能な太陽電池や光触媒を開発する上で欠かせない共通課題である。そのためには、格子欠陥を適切に評価する手法が不可欠となるが、材料の種類(組成や形状)を選ばず汎用的に適用できる測定手法はこれまで開発されてこなかった。
本研究では、欠陥濃度を精密に制御した半導体光触媒の活性を調べ、欠陥濃度と活性の関係をはじめて明らかにした。さらには新規に開発した分光学的手法により、その表面欠陥のエネルギー準位を特定できることも示した。これらの事実より、本研究の学術的な価値は極めて高いと認められる。
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