Collaborative Research: Tailoring Electron and Spin Transport in Single Molecule Junctions

信息经济的增长和人工智能的重要性日益提高，推动了对急剧增加的计算能力的需求。现有的半导体技术无法以所需的速度满足这些需求。此外，计算和数据存储的大规模增长所带来的能源需求可能会严重限制信息处理的数量和速度。因此，迫切需要新的节能技术。该研究项目汇集了一个在理论、合成和高级表征方面具有综合专业知识的团队。该团队将设计和合成新的分子，并开发新的表征方法，以便为在单分子的最终尺寸限制下运行的电子设备铺平道路。这项研究将使单分子有效的电荷流动和开关成为可能，并允许创造高密度低功耗电子产品。研究人员将进一步展示如何将量子现象用于单分子器件，以新的有效方式编码信息，并将高密度分子阵列的功耗降至最低。该研究团队将从代表性不足的群体中培养本科生和研究生，从传统上服务不足的农村和城市社区培养未来的科学领袖，并让从武装部队过渡到高等教育的退伍军人参与其中。尽管进行了广泛的研究来了解单分子电子器件中的量子输运，但对于如何系统地定制分子中的电荷和自旋输运，仍然缺乏预测性和可推广的分子水平理解。这种理解的出现受到分子-电极界面上复杂的多体相互作用和所研究的不同分子结构的广泛变化的阻碍。提出的理论驱动研究通过i)系统地改变有机半导体框架以定制组合分子/电极系统，以捕获界面相互作用对能级排列的超大影响，从而捕获单分子结的电导；ii)寻求显著增强电荷输运或使用系统设计的全有机自由基创建自旋极化电流的途径。从所提出的研究见解提供了新的设计规则来控制单分子和跨分子电极界面的电荷流。研究人员还将开发关键原理，使自旋电流无需铁磁电极即可流动。这些问题是有机半导体材料科学的基本主题，超越了分子的特定类别和单分子中量子输运的特定挑战。它们更广泛地涉及有机电子学领域，包括分子和薄膜有机电子学。协同研究结合了新材料的合成、单分子极限材料的设计和表征，为提高高性能计算和数据分析的能源效率奠定了基础，最终使新的信息处理模式成为可能，对美国制造业产生前所未有的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical DescriptionThe growth of the information economy and the rising importance of artificial intelligence are driving a need for dramatically increased computing power. Such demands cannot be met at the required pace using existing semiconductor technologies. In addition, energy requirements to power the massive increase in computing and data storage may present a serious limitation to how much and how fast information can be processed. New energy-efficient technologies are therefore urgently needed. This research project brings together a team with combined expertise in theory, synthesis, and advanced characterization. The team will design and synthesize novel molecules and develop new characterization methods in order to pave the way to electronic devices that operate at the ultimate size limit of single molecules. This research will enable efficient charge flow and switching in single molecules and allow for the creation of high-density low-power electronics. The investigators will further demonstrate how quantum phenomena can be used in single molecule devices to encode information in new and efficient ways, and to minimize power consumption in high-density molecular arrays. The research team will train undergraduate and graduate students from underrepresented groups, educate future scientific leaders from traditionally underserved rural and urban communities, and involve veterans who transition from the armed services into higher education.Technical DescriptionDespite extensive research to understand quantum transport in single molecule electronic devices, a predictive and generalizable molecular-level understanding of how to systematically tailor charge- and spin-transport through molecules is still missing. The emergence of such an understanding is hampered by the complex many-body interactions at the molecule-electrode interface and the wide variation of different molecular constructs investigated. The proposed theory-driven research addresses this challenge by i) systematically varying the organic semiconductor framework to tailor the combined molecule/electrode system, to capture the outsized influence of interfacial interactions on energy level alignment and hence conductance in single molecule junctions; and ii) seeking to significantly enhance charge-transport or to create pathways towards spin-polarized current using systematically designed all-organic radicals. Insights from the proposed research provide new design rules for controlling charge-flow in single molecules and across molecule-electrode interfaces at will. Investigators will also develop key principles that enable the flow of spin-current without the need for ferromagnetic electrodes. These issues are fundamental themes in the materials science of organic semiconductors that transcend the specific classes of molecules and the specific challenges of quantum transport in single molecules. They pertain to the field of organic electronics more broadly, encompassing molecular and thin film organic electronics. The synergistic research, combining synthesis of new materials, materials by design and characterization at the single molecule limit, lays the foundation for improved energy-efficiency in high-performance computing and data analysis, which ultimately enables new information processing modalities with potentially unprecedented impact on US manufacturing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.