ハリド二重ペロフスキットの調節欠陥
Nathan R Wolf1, Adam Jaffe1, Adam H Slavney1
1Department of Chemistry, Stanford University, Stanford, California94305, United States.
Journal of the American Chemical Society
|November 7, 2022
まとめ
高圧は,ブロミン空隙の欠陥を調節することによって,ハリドペロブスキットの伝導性を劇的に変化させます. この浅い状態から深い状態への移行は,これらの半導体内の電子輸送に影響します.
科学分野:
- 材料科学
- 固体物理学
- 半導体物理学
背景:
- ドーパントの欠陥は,電荷キャリアを閉じ込めたり生成したりすることで,半導体電子輸送に重大な影響を及ぼします.
- ハリドペロブスキットは,かなりの圧力反応で知られている技術的に重要な半導体です.
- ハリドペロブスキート内の欠陥に対する高圧の影響は,実験的に未調査のままである.
研究 の 目的:
- 小帯域の二重ペロブスキートCs2AgTlX6 (X = ClまたはBr) に高圧による構造的,光学的,および電子的影響を調査する.
- これらの材料の観測された光電子的振る舞いにおける圧力誘発の欠陥チューニングの役割を決定する.
主な方法:
- Cs2AgTlX6 (X = Clまたは Br) の単結晶を56GPaまで圧縮する.
- 異なる圧力下での構造的,光学的,電子的性質の測定
- 軌道の相互作用を分析して 欠陥の行動を理解する.
主要な成果:
- 軽度の圧縮 (1.7 GPa) は,Cs2AgTlBr6の伝導性を数桁増加させ,帯域間隔 (0.94から0.7 eV) を減少させた.
- 高圧で観察された複雑な光電子的振る舞い, 1.2 eVのバンドギャップの変動と10 ^ 4までの伝導性の変化.
- 導電性の変化は,プレッシャーによるブローム空位欠陥の浅い状態から1.5GPa近くの深い状態への移行と相関しています.
結論:
- 圧力誘発によるブローム空隙の調節は,帯差変化とは関係なく,ハリドペロブスキットの伝導性を大幅に変化させます.
- 浅から深い欠陥への移行は,Tls- Brp抗結合相互作用の圧力低下によって引き起こされる.
- ハロゲン空白は,s軌道由来伝導帯を持つハリド二重ペロブスキットの浅いドナーである可能性が高い.
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