半導体ポリマーにおける電光発光の量子効率の改善
Yong Cao1, Ian D Parker1, Gang Yu1
1UNIAX Corporation, 6780 Cortona Drive, Santa Barbara, California 93117-3022, USA.
Nature
|April 19, 2018
まとめ
研究者は,ポリマー発光ダイオードで,材料を混合することによって,電光発光と光発光効率の50%の比率を達成しました. この突破は強く結合するエクシトンの理論上の限界を超え,弱いエクシトンの結合エネルギーを示しています.
科学分野:
- 材料科学
- オーガニック電子
- フォト物理学
背景:
- 結合されたポリマーは,ポリマー発光ダイオード (PLED) のために不可欠な発光性を表します.
- PLEDの性能は,光発光 (PL) QEに対する電光発光 (EL) 量子効率 (QE) によって制限されます.
- EL:PL QEの理論的限界は,強く結合したエキストンでは25%ですが,弱い結合したエキストンでは1に近づくことができます.
研究 の 目的:
- PLEDにおける EL:PL QE比を向上させる方法を調査する.
- 結合ポリマーにおけるエクシトン結合エネルギーと効率の関係を探求する.
- PLEDの理論的な効率の限界が超えられるかどうかを判断する.
主な方法:
- 電子輸送材料と混合された結合ポリマーを使用してPLEDの製造.
- 電子注入効率を向上させるための材料混合の最適化.
- 電気発光と光発光の量子効率の測定と比較
主要な成果:
- 開発したPLEDでは EL:PL QE比率が約50%に達した.
- この比率は,強く結合したシングレットとトリプルエットエクシトンの 25% の理論的限界を大幅に超えています.
- 結果は,弱いエクシトン結合エネルギーまたはシングレット結合状態の形成のより高い確率を示唆しています.
結論:
- 電子輸送材料を混ぜることで,電子注入とPLEDの効率が効果的に向上します.
- これらの発見は,これらのPLEDにおける主要な興奮状態として強く結合されたエキストンという仮定に異議を唱える.
- この研究は,高効率の有機発光装置を設計するための道を開きます.
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