Band gap engineering in blended organic semiconductor films based on dielectric interactions
Band gap engineering in blended organic semiconductor films based on dielectric interactions
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DOI：
10.1038/s41563-021-01025-z
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发表时间：
2021-06-10
期刊：
影响因子：
41.2
通讯作者：
Leo, Karl
中科院分区：
文献类型：
--
作者：
Ortstein, Katrin;Hutsch, Sebastian;Leo, Karl
混合有机分子以调整其能级是目前研究的一种方法，用于设计有机半导体的体积和界面光电特性。实验证明，通过混合具有不同能量的相似卤化衍生物来控制静电效应，电离能和电子亲和能可以均匀地向同一方向移动。我们发现有机半导体的能隙也可以通过混合来调节。我们以不同环数的寡硫吩为例，研究了它们的结构和电子性质。光电子能谱和反光电子能谱显示了单粒子间隙的可调性，光学间隙表现出类似但较小的效应。理论分析表明，这种调谐主要是由介电常数随混合比的变化引起的。进一步的研究将探索这种能级工程策略对光电器件的实际影响。具有不同电离能和电子亲和间隙的噻吩分子的紧密混合导致介电常数的变化，导致单粒子水平上的间隙变化，通过控制混合比可以精细地调节。
Blending organic molecules to tune their energy levels is currently being investigated as an approach to engineer the bulk and interfacial optoelectronic properties of organic semiconductors. It has been proven that the ionization energy and electron affinity can be equally shifted in the same direction by electrostatic effects controlled by blending similar halogenated derivatives with different energetics. Here we show that the energy gap of organic semiconductors can also be tuned by blending. We use oligothiophenes with different numbers of thiophene rings as an example and investigate their structure and electronic properties. Photoelectron spectroscopy and inverse photoelectron spectroscopy show tunability of the single-particle gap, with the optical gaps showing similar, but smaller, effects. Theoretical analysis shows that this tuning is mainly caused by a change in the dielectric constant with blend ratio. Further studies will explore the practical impact of this energy-level engineering strategy for optoelectronic devices.Changes in dielectric constant due to intimate mixing of thiophene molecules with different gaps between ionization energy and electron affinity induce gap variations at the single-particle level, finely tunable by controlling the mixture ratio.