Electron-Hole Pairs Generated in the Crystalline Phase of Polymer Diodes Studied by Electrically Detected Magnetic Resonance Techniques
Electron-Hole Pairs Generated in the Crystalline Phase of Polymer Diodes Studied by Electrically Detected Magnetic Resonance Techniques
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用电检测磁共振技术研究聚合物二极管晶相中产生的电子空穴对
DOI：
10.1021/acs.jpcc.9b07796
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发表时间：
2019
影响因子：
3.7
通讯作者：
and Katsuichi Kanemoto
中科院分区：
文献类型：
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作者：
Kousuke Iwamoto;Yuto Hayakawa;Shuto Hatanaka;Takayuki Suzuki;and Katsuichi Kanemoto
利用电探测磁共振（EDMR）技术研究了聚3-己基噻吩（P3 HT）二极管中电子空穴对的性质。对于给定的空穴密度，EDMR强度随着注入电子密度的增加而增加，表明EDMR信号来自e-h对。EDMR谱由两条高斯曲线组成，其中一条给出的ag值与空穴载流子的ag值非常相似，这表明EDMR谱是由形成e-h对的空穴和电子载流子的电子自旋共振（ESR）谱之和给出的。二极管工作下的载流子和电子-氢对之间的偏置相关性直接从载流子的近红外（NIR）光谱和电子-氢对的EDMR的独立测量检查。当偏置增加到阈值以上时，尽管NIR信号逐渐增加，但EDMR信号强烈降低，这提供了在偏置区域中通过电场解离e-h对的证据。由于电子对的这一特性，二极管内部载流子和电子对之间的相关性会根据偏置幅度而变化：载流子和电子对共存或仅存在载流子。由于P3 HT膜的结晶相，推测e-h对形成于不同的层。虽然来自层间e-h对的EDMR信号的强度很小，但是当样品暴露于空气中时，强度大幅增加，这表明形成了结合氧的磁反应物质。
The properties of electron–hole (e–h) pairs generated in a working poly(3-hexylthiophene) (P3HT) diode are investigated by electrically detected magnetic resonance (EDMR) techniques. The EDMR intensity is shown to increase with increasing density of injected electrons for a given hole density, demonstrating that the EDMR signal arises from an e–h pair. The EDMR spectrum consists of two Gaussian curves, one of which gives ag-value very similar to that of hole carriers, suggesting that the EDMR spectrum is given by the sum of electron spin resonance (ESR) spectra from hole and electron carriers forming e–h pairs. Bias-dependent correlation between carriers and e–h pairs under diode operation is examined directly from independent measurements of near-infrared (NIR) spectroscopy for carriers and EDMR for e–h pairs. When the bias is increased to above a threshold, the EDMR signal is strongly reduced despite a gradual increase in the NIR signals, providing evidence that the e–h pairs are dissociated by an electric field in the bias region. Because of this property of the pair, the correlation between the carriers and e–h pairs inside the diode changes depending on the bias magnitude: the carriers and e–h pairs coexist or only the carriers exist. The e–h pair is presumed to be formed across different lamellae because of the crystalline phase of the P3HT film. Although the intensity of the EDMR signal from the interlamellar e–h pair is small, the intensity increases substantially when the sample is exposed to air, suggesting the formation of a magnetoreactive species that incorporates oxygen.