基于分子自组装的稳定可重复分子整流器

Repeatable molecular rectifier based on self-assembled monolayers

以分子自组装的方法在金电极表面制备了“2-巯基-5-磺酸基苯并咪唑（MBIS）”的单层有机分子膜,并用掠角反射红外光谱（RAIRS）对其进行了表征.覆盖有MBIS单分子层的金膜表面具有明显的亲水性,其接触角为31.3°,而纯金膜表面的接触角为106.6°。用扫描隧道显微镜（STM）测试了MBIS单分子膜的整流性质,测得在偏压±1V时的整流比为20.6。末端含有磺酸基的MBIS单分子层膜能够忍受真空热蒸发方法蒸镀金属顶电极的冲击,因此容易用通常的热蒸镀方法制备夹层器件。“金/MBIS单层分子膜/银”器件首次测得的整流比为11.8（±2V）,随后20次连续测量显示整流比为6.62～8.95（±2V）。“金/MBIS单层分子膜/铜”器件的整流比约为4（±1V）,整流器件之间有良好的稳定性及重现性。

An organic monolayer of 2-mercapto-5-benzimidazolesulfonic acid sodium salt（MBIS） was grown on the surface of a gold electrode by SAMs（self-assembled monolayers）,which was characterized by grazing-angle reflection-absorption infrared spectroscopy（RAIRS）.Au substrate coated with MBIS monolayer was obviously hydrophilic with contact angle of 31.3°,while bare Au of 106.6°.Rectification ratio（RR） of such an MBIS monolayer on a gold electrode was found to be 20.6 at ±1V,based on the measurement by scanning tunneling microscopy（STM）.As the terminal sulfonic group protected the MBIS monolayer from the impact of vacuum thermal evaporation of top electrode,sandwich devices could be fabricated well through common thermal evaporation methods.The device of Au/monolayer MBIS/Ag showed the rectification ratio of 11.8 at ±2V at the first measurement,and nearly consistent rectifying property（RR from 6.62-8.95） in the next 20 continuous voltage scanning cycles.Device of Au/monolayer MBIS/Cu were also demonstrated with RR of about 4 at ±1V,and the rectifying property was stable and repeatable among different devices.