Park Sohyun, Kim Hwa Rang, Kim Juhee, Hong Byung-Hee, Yoon Hyo Jae
Department of Chemistry, Korea University, Seoul, 02841, South Korea.
Department of Chemistry, Seoul National University, Seoul, 08826, South Korea.
Adv Mater. 2021 Oct;33(41):e2103177. doi: 10.1002/adma.202103177. Epub 2021 Aug 27.
Enhancing thermopower is a key goal in organic and molecular thermoelectrics. Herein, it is shown that introducing noncovalent contact with a single-layer graphene (SLG) electrode improves the thermopower of saturated molecules as compared to the traditional gold-thiolate covalent contact. Thermoelectric junction measurements with a liquid-metal technique reveal that the value of Seebeck coefficient in large-area junctions based on n-alkylamine self-assembled monolayers (SAMs) on SLG is increased up to fivefold compared to the analogous junction based on n-alkanethiolate SAMs on gold. Experiments with Raman spectroscopy and field-effect transistor analysis indicate that such enhancements benefit from the creation of new in-gap states and electron doping through noncovalent interaction between the amine anchor and the SLG electrode, which leads to a reduced energy offset between the Fermi level and the transport channel. This work demonstrates that control of interfacial bonding nature in molecular junctions improves the Seebeck effect in saturated molecules.
提高热电功率是有机和分子热电学的一个关键目标。在此表明，与传统的金硫醇共价接触相比，引入与单层石墨烯（SLG）电极的非共价接触可提高饱和分子的热电功率。采用液态金属技术进行的热电结测量表明，基于SLG上的正烷基胺自组装单分子层（SAMs）的大面积结中的塞贝克系数值，与基于金上的正烷硫醇盐SAMs的类似结相比增加了五倍。拉曼光谱和场效应晶体管分析实验表明，这种增强得益于新的能隙态的产生以及通过胺锚与SLG电极之间的非共价相互作用进行的电子掺杂，这导致费米能级与传输通道之间的能量偏移减小。这项工作表明，控制分子结中的界面键合性质可改善饱和分子中的塞贝克效应。
