Oehzelt Martin, Koch Norbert, Heimel Georg
1] Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Bereich Solarenergieforschung, Albert-Einstein-Straße 15, 12489 Berlin, Germany [2] Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany.
Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany.
Nat Commun. 2014 Jun 18;5:4174. doi: 10.1038/ncomms5174.
Minimizing charge carrier injection barriers and extraction losses at interfaces between organic semiconductors and metallic electrodes is critical for optimizing the performance of organic (opto-) electronic devices. Here, we implement a detailed electrostatic model, capable of reproducing the alignment between the electrode Fermi energy and the transport states in the organic semiconductor both qualitatively and quantitatively. Covering the full phenomenological range of interfacial energy level alignment regimes within a single, consistent framework and continuously connecting the limiting cases described by previously proposed models allows us to resolve conflicting views in the literature. Our results highlight the density of states in the organic semiconductor as a key factor. Its shape and, in particular, the energy distribution of electronic states tailing into the fundamental gap is found to determine both the minimum value of practically achievable injection barriers as well as their spatial profile, ranging from abrupt interface dipoles to extended band-bending regions.
最小化有机半导体与金属电极界面处的电荷载流子注入势垒和提取损耗对于优化有机（光）电子器件的性能至关重要。在此，我们建立了一个详细的静电模型，该模型能够定性和定量地再现电极费米能级与有机半导体中传输态之间的对齐情况。在一个统一的框架内涵盖界面能级对齐机制的整个唯象学范围，并连续连接先前提出的模型所描述的极限情况，这使我们能够解决文献中相互矛盾的观点。我们的结果突出了有机半导体中的态密度作为一个关键因素。发现其形状，特别是拖尾到基本能隙中的电子态的能量分布，既决定了实际可实现的注入势垒的最小值，也决定了它们的空间分布，范围从陡峭的界面偶极子到扩展的能带弯曲区域。
