Molecular Diodes and an Approch to Single Molecule Electronics

分子电子学代表了器件小型化的终极挑战：它提供了设计具有特定特性的组件的方法，与此相关，申请人小组最近的一项发现导致了迄今为止分子二极管的最高内在整流比（Ashwell等人，物理学家）。化学。化学。物理学报，2006,8(3):391 - 391。报告的电流比为3000 +/-1 V，与另一组报告的下一个最高值相比，提高了150倍。这一发现引起了极大的关注：该论文于2006年6月被指定为热门文章，此后连续7个月被英国皇家化学学会网站列为十大论文，访问量最高的次数为6次；在韩国、波兰和英国的杂志上，还刊登了该报纸的封面和社论。有机薄膜内部整流的例子仍然很少，直到现在，报道的电流比太小，没有任何实际意义。上述发现克服了这一缺陷，本提案的实验挑战性目标是在超薄膜和最终单分子器件研究时提高分子二极管的性能。它将通过(i)优化空间阻碍Au/D-bridge-D*-bridge-A/Au和Au/D-bridge-A*-bridge-A/Au结构中的整流供体-受体序列（星号表示较弱的电活性成分）和（ii）开发非侵入性接触技术，涉及制造后单分子或小分子簇跨越纳米级金电极间隙的自组装。目标是利用迄今为止的发现，在+/-1 V下将整流比提高到100,000。

Molecular electronics represents the ultimate challenge in device miniaturisation: it provides the means to design components with specific properties and, in relation to this, a recent discovery from the applicant's group has resulted in the highest intrinsic rectification ratio to date from a molecular diode (Ashwell et al., Phys. Chem. Chem. Phys. 2006, 8, 3314). The reported current ratio of 3000 at +/-1 V represents a 150-fold improvement compared with the next highest reported value from another group. The discovery has attracted much attention: the paper was designated as a Hot Article in June 2006 and it has since been listed as a Top Ten paper on the Royal Society of Chemistry website for seven consecutive months and most accessed six times; it also features on the journal's cover and there are editorial highlights of the paper in Korean, Polish and UK journals. There are still few examples of intrinsic rectification from organic films and, until now, the reported current ratios have been far too small to have any practical significance. The aforementioned discovery overcomes this deficiency and the experimentally challenging objective of this proposal is to enhance the performance of molecular diodes when studied as ultra-thin films and ultimately single molecule devices. It will be attempted by (i) optimising the rectifying donor-acceptor sequence in sterically hindered Au/D-bridge-D*-bridge-A/Au and Au/D-bridge-A*-bridge-A/Au structures in which the asterisks represent weaker electroactive components and (ii) developing non-invasive contacting techniques that involve the post-fabrication self-assembly of single molecules or small molecular clusters across nano-sized gold electrode gaps. The aim is to utilise the discoveries made to date to increase the rectification ratio to 100,000 at +/-1 V.