Molecular semiconductors: Terahertz spectroscopy of charge transport on the nanoscale

分子半导体：纳米级电荷传输的太赫兹光谱

• 批准号: 420459768
• 负责人: Professor Dr. Roland Kersting
• 金额: --
• 依托单位: Lehrstuhl für Photonik und Optoelektronik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/420459768?language=en
• 关键词: Molecular; semiconductors; Terahertz; spectroscopy; charge

Over the past two decades, the development of organic field-effect transistors (OFETs) brought first applications into reach. The mobilities obtained on thin-film OFETs, however, converged at values of about 10 cm2/Vs, which may not be sufficient for many applications. Additionally, the fundamental understanding of carrier transport has not reached the level known from inorganic semiconductors. With the proposed research, we want to shed light on two processes that are expected to slow down transport in molecular semiconductors. These are the carrier-phonon interaction that leads to polarons and the dynamic localization of charges.The proposed work is stimulated by the insight that both, polarons and dynamic localization may be efficiently screened within the channel of OFETs, which should lead to free carriers and Bloch-like transport. In order to access these fundamental properties of carrier transport, we will perform terahertz (THz) transmission experiments that probe the local transport on the nanoscale and are not affected by grain boundaries or other extrinsic parameters. From the THz data, effective masses of the carriers, as well as their scattering times, will be obtained. Their temperature dependencies will show how polaron formation and dynamic localization affect transport. Of particular interest is the extent to which these processes are screened by charge carriers at densities, which are typical for the inversion layer of OFETs. The expected results are not only of fundamental interest, but they also may stimulate the development of novel molecular semiconductors and may lead to a significant leap in mobilities that brings OFETs closer to application.

在过去的二十年中，有机田间效应晶体管（OFET）的开发使第一应用物达到了影响。但是，在薄膜上获得的迁移率在约10 cm2/vs的值时收敛，这对于许多应用可能不足。此外，对载体运输的基本理解尚未达到无机半导体已知的水平。通过拟议的研究，我们希望阐明两个过程，这些过程有望减慢分子半导体的转运。这些是导致极性和电荷动态定位的载波 - 波相互作用。拟议的工作受到洞察力的刺激，即极性和动态定位都可以在OFET的通道内有效筛选，这应该导致自由载体和Bloch样运输。为了访问载流子传输的这些基本特性，我们将执行Terahertz（THZ）传输实验，该实验探测纳米级上的局部运输，并且不受晶界或其他外部参数的影响。从THZ数据中，将获得载体的有效质量及其散射时间。他们的温度依赖性将显示极性形成和动态定位如何影响运输。特别有趣的是，这些过程在密度下通过电荷载体筛选的程度，这对于OFET的反转层是典型的。预期的结果不仅具有基本兴趣，而且还可能刺激新型分子半导体的发展，并可能导致迁移率的显着飞跃，从而使OFET更接近应用。