鉛のないペロフスキットにおける非同期光刺激電子と構造の緩解
Cunming Liu, Yingqi Wang1, Huifang Geng2
1Center for High Pressure Science and Technology Advanced Research , Shanghai 201203 , China.
Journal of the American Chemical Society
|July 31, 2019
まとめ
無鉛のペロブスキットは有望だが,電荷輸送能力は低い. 超高速のX線吸収スペクトロスコーピーは セルフトラップされた穴と キャリアの移動を阻害する長寿の歪んだ状態を明らかにしました
科学分野:
- 材料科学
- 固体物理学
- 太陽光発電
背景:
- 無鉛ペロブスキットは有毒な鉛ハリドペロブスキット (LHP) の代替品として調査されています.
- これらの材料は,分散エネルギー帯により,より安定した構造と潜在的に優れた電荷キャリアの移動性を提供します.
- しかし,予期せぬほど 負荷の運びが悪いので 応用が限られている.
研究 の 目的:
- 欠乏した電荷媒体の輸送の根本的なメカニズムの調査を空白でオーダーされた無鉛のペロフスキートで行う.
- 超高速スペクトロスコーピーを用いて,Cs3Bi2Br9の光刺激電子と構造ダイナミクスを直接探査する.
主な方法:
- 超高速の元素特異性X線一時吸収 (XTA) スペクトロスコーピーを採用した.
- Cs3Bi2Br9における光刺激された電荷媒体の動態と格子構造を研究した.
主要な成果:
- Br中心の光生成孔の急速な自己トラップが発見され,局所的な格子歪み (V_k中心形成) を引き起こした.
- 驚くほど長生き (∼59 μs) 構造的歪曲を特定し,キャリア再結合よりも遅い.
- この長期にわたる歪みは,チャージキャリアの輸送を阻害する可能性があります.
結論:
- 鉛のないペロブスキットの負荷輸送は,穴の自己トラップと大きな格子歪みに関連しています.
- 長期にわたる歪んだ状態は一時的な背景として作用し,電荷キャリアの移動性に悪影響を及ぼします.
- これらのダイナミクスを理解することは,効率的な無鉛ペロブスキート材料の設計に不可欠です.
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