オーガニックヘテロジャンクションにおける再結合と電容器のような電荷の蓄積の減少
Kyra N Schwarz, Paul B Geraghty, Valerie D Mitchell
1Department of Physics , Swansea University , Singleton Park , Swansea , Wales SA2 8PP , United Kingdom.
Journal of the American Chemical Society
|January 11, 2020
まとめ
研究者らは,特定の有機光伏 (OPV) 活性層形態がナノスケール電場を作り,電荷再結合を大幅に減少させることを発見しました. これにより,より厚いOPVデバイスは,バイ分子再結合からキャリアを保護することにより,高い効率を維持できます.
科学分野:
- 材料科学
- 物理化学
- オーガニック電子
背景:
- オーガニック光伏 (OPV) 装置の効率は向上していますが,電荷キャリア再結合は重要な制限です.
- 再結合は,特にインターフェイスで,光生成電子と穴の間の拡散とクーロンビック吸引により発生します.
研究 の 目的:
- OPV活性層における電荷再結合抑制におけるナノスケール電場の役割を調査する.
- 特定の活性層の形態が電荷キャリアのダイナミクスとデバイスの性能にどのように影響するかを理解する.
主な方法:
- キャリアダイナミクスを探査するためにフェムト秒間スペクトロスコピーを利用しました.
- ナノスケールの電場と一時的なスターク効果を測定した
- チャージキャリア再結合率を分析し,理論的な予測 (ランゲヴィン理論) と比較した.
主要な成果:
- 自由キャリアの間の電場に起因する,重要な一時的なスターク効果 (∼487 kV/cm) が観察された.
- ランゲヴィン理論の予測と比較して,再結合を約2000倍減らすエネルギーカスケードを作成する特定の活性層形態を特定した.
- これらの形状を持つより厚いOPV膜 (>600 nm) は,増加したキャリア密度と再結合からの保護により> 8%の効率を維持することが示されています.
結論:
- OPV活性層の特定のナノスケール形態は,空間的に電荷を分離することによって二分子再結合を緩和することができます.
- 大量ヘテロジュンクションは,コンデンサとして機能し,インターフェースから分離された電荷を保存します.
- これらの発見は,形質学的制御を通じてOPVのパフォーマンスをさらに向上させるための経路を示唆しています.
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