DMREF: Metallic-type transport in polymers: Establishing materials design criteria and predicting structure/property interrelations

非技术描述：提出了一个材料设计框架，它将提供对决定有机半导体中电荷传输性质的因素的定量见解，并将为加速材料发现提供可验证的假设。部分原因是，尽管价值数十亿美元的有机电子工业是基于有机半导体的性能和加工性的独特组合，但对这些材料来说，溶解性/加工性、分子间相互作用和其他影响电荷载流子离域的因素仍然不完全清楚，电荷载流子离域决定了传输特性。关键性能可以微妙地依赖于化学结构和工艺条件，而且通常，性能和工艺参数的变化以不明显的方式交织在一起。这造成了一项艰巨的任务，即建立全面的结构/加工/性质相互关系，通常将材料发现减少到启发式的、耗时的、昂贵的研究中。为了揭示结构/加工和传输性质的复杂相互作用，来自佐治亚理工学院(GT)、马萨诸塞大学阿默斯特分校(UMassachusetts Amherst)和洛斯阿拉莫斯国家实验室(LANL)的材料化学家、材料工程师、超快光谱学家和理论家组成了一个多学科团队。这项研究将提供关键的见解，使材料的定量设计能够同时优化迁移率和导电性。它还将向广大社区提供一个广泛的数据库，可以挖掘这些数据库来推进材料科学发现平台，并将用于教育。我们将开发具有改进的参数化的理论工具，允许对更广泛的材料集进行建模。目标材料将被用于各种应用，其中包括电极、热电材料和电荷提取层。高度多样化的团队将接触到服务不足的社区，招募女性和代表性不足的科学家和工程师在其共享计划中开展研究，但也通过各种参与计划和公共宣传活动与高中和公众进行广泛互动。技术描述：该研究解决了电荷载流子相干长度和传输特性如何与掺杂有机材料的特定结构特征相关的基本问题。光学光谱(吸收光谱、光致吸收光谱、光致发光光谱、光致发光激发光谱和二维相干激发光谱)以及热分析和X射线衍射数据将被用来建立一个利用各种掺杂剂的掺杂聚合物、低聚物和小分子的数据库。LANL将使用现有的理论工具对关键的光谱观测数据进行建模，使用原子方法的第一性原理计算、非绝热分子动力学模拟和参数化的Holstein格子模型来模拟电荷的量子动力学，重点是材料中载流子的空间相干长度。非线性光谱将被用来改进量子动力学模型的细节，因为它们不仅提供了种群的细节，而且还提供了时间和空间相干动力学的细节。特别是，这些测量可以将均匀的激发线宽从总的光谱线形中分离出来，从而提供一个非常灵敏的空间相干性探测器，受到导致载流子局部化的量子动力学的限制。PIS还计划将DMREF聚合物半导体工具箱和数据库作为开源发布，并通过确保感兴趣的研究人员能够为DMREF聚合物半导体工具箱和数据库代码库做出贡献，围绕该语言建立一个用户社区。这将使该项目有更广泛的增长。这方面对高级数字基础设施办公室的软件集群特别感兴趣，该办公室为这一奖项提供了共同资金。

Non-technical Description: A materials design framework is proposed that will provide quantitative insights into what determines charge transport properties in organic semiconductors, and will provide verifiable hypotheses towards accelerated materials discovery. The motivation is partly that, although the multibillion dollar organic electronic industry is based on a unique combination of performance and processability of organic semiconductors, solubility/processability, intermolecular interactions, and other factors impacting delocalization of charge carriers, which determines transport properties, are still not fully understood for these materials. Critical properties can depend subtly on chemical structure and processing conditions and, often, changes in properties and processing parameters are intertwined in non-obvious ways. This creates a daunting task to establish comprehensive structure/processing/property interrelations, often reducing materials discovery to heuristic time-consuming, expensive studies. To unravel the complex interaction of structure/processing and transport properties, a multidisciplinary team of materials chemists, materials engineers, ultrafast spectroscopists, and theorists from Georgia Tech (GT), University of Massachusetts Amherst (UMass), and Los Alamos National Laboratory (LANL), has been assembled. This research will provide critical insights that will enable the quantitative design of materials that optimize both mobility and conductivity. It will also make available to a broad community an extensive database that can be mined to advance materials science discovery platforms, and that will be used in education. We will develop theoretical tools with improved parameterization, allowing the modeling of a broader set of materials. The target materials will be employed in a variety of applications including, amongst others, electrodes, thermoelectric materials, and charge-extraction layers. The highly diverse team will reach out to under-served communities, by recruiting female and under-represented scientists and engineers to carry out research in its shared program, but also through extensive interactions with high schools and the public through a variety of engagement programs and public outreach events.Technical Description: The research addresses fundamental questions of how charge-carrier coherence length and transport properties correlate with specific structural features in doped organic materials. Optical spectroscopies (absorption, photoinduced absorption, photoluminescence, photoluminescence excitation, and two-dimensional coherent excitation spectra), along with thermal analysis and X-ray diffraction data, will be used to construct a database on doped polymers, oligomers and small molecules, utilizing a variety of dopants. Key spectral observables will be modeled with existing theoretical tools at LANL, using first-principle calculations with atomistic approaches, nonadiabatic molecular dynamics simulations, and parameterized Holstein lattice models to simulate quantum dynamics of charges, focusing on spatial coherence lengths of charge carriers in materials. Nonlinear spectroscopies will be used to refine the details of the quantum dynamics models, as they provide details of not only population but also temporal and spatial coherence dynamics. In particular, these measurements can isolate the homogeneous excitation linewidth from the total spectral lineshape, thereby providing a very sensitive probe of spatial coherence, limited by the quantum dynamics that lead to carrier localization. The PIs also plan to release the DMREF Polymeric Semiconductor Toolbox and Database as open source and build a user community around the language by ensuring that interested researchers are able to contribute to the DMREF Polymeric Semiconductor Toolbox and Database codebase. This will allow a wider growth of the project. This aspect is of special interest to the software cluster in the Office of Advanced Cyberinfrastructure, which has provided co-funding for this award.