Shen Shaocheng, Shiri Mehrdad, Mahalingam Paramasivam, Tang Chaolong, Bills Tyler, Bushnell Alexander J, Balandin Tanya A, Mejía Leopoldo, Zhang Haixin, Xu Bingqian, Franco Ignacio, Azoulay Jason D, Wang Kun
Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States.
Department of Physics, University of Miami, Coral Gables, Florida 33146, United States.
J Am Chem Soc. 2025 Jun 18;147(24):20310-20317. doi: 10.1021/jacs.4c18150. Epub 2025 May 1.
A grand challenge in molecular electronics is the development of molecular materials that can facilitate efficient long-range charge transport. Research spanning more than two decades has been fueled by the prospects of creating a new generation of miniaturized electronic technologies based on molecules whose synthetic tunability offers tailored electronic properties and functions unattainable with conventional electronic materials. However, current design paradigms produce molecules that exhibit off-resonant transport under low bias, which limits the conductance of molecular materials to unsatisfactorily low levels─several orders of magnitude below the conductance quantum 1 ─and often results in an exponential decay in conductance with length. Here, we demonstrate a chemically robust, air-stable, and highly tunable molecular wire platform comprised of open-shell donor-acceptor macromolecules that exhibit remarkably high conductance close to 1 over a length surpassing 20 nm under low bias, with no discernible decay with length. Single-molecule transport measurements and calculations show that the ultralong-range resonant transport arises from extended π-conjugation, a narrow bandgap, and diradical character, which synergistically enables excellent alignment of frontier molecular orbitals with the electrode Fermi energy. The implementation of this long-sought-after transport regime within molecular materials offers new opportunities for the integration of manifold properties within emerging nanoelectronic technologies.
分子电子学中的一个重大挑战是开发能够促进高效长程电荷传输的分子材料。二十多年来的研究一直受到基于分子创造新一代微型化电子技术前景的推动，这些分子的合成可调性提供了传统电子材料无法实现的定制电子特性和功能。然而，目前的设计范式产生的分子在低偏压下表现出非共振传输，这将分子材料的电导率限制在令人不满意的低水平——比电导量子1低几个数量级——并且常常导致电导率随长度呈指数衰减。在这里，我们展示了一个由开壳供体-受体大分子组成的化学稳定、空气稳定且高度可调的分子线平台，该平台在低偏压下，在超过20纳米的长度上表现出接近1的极高电导率，且电导率没有明显的长度衰减。单分子传输测量和计算表明，超长程共振传输源于扩展的π共轭、窄带隙和双自由基特性，这些特性协同作用，使前沿分子轨道与电极费米能级实现了良好的对齐。在分子材料中实现这种长期追求的传输机制为新兴纳米电子技术中多种特性的集成提供了新的机会。
