Molecular Diodes and an Approch to Single Molecule Electronics

分子电子学代表了器件封装中的最终挑战：它提供了设计具有特定特性的部件的手段，并且与此相关，申请人小组的最近发现已经导致了迄今为止来自分子二极管的最高固有整流比（Ashwell等人，Phys.Chem.Chem.Phys.2006，8，3314）。在+/-1 V时报告的电流比为3000，与另一组报告的次高值相比，改善了150倍。这一发现引起了广泛的关注：该论文在2006年6月被指定为热门文章，此后连续七个月被列为皇家化学学会网站的十大论文，最多访问六次;它还出现在该杂志的封面上，并在韩国，波兰和英国期刊上发表了该论文的编辑摘要。仍然有几个例子，从有机薄膜的本征整流，直到现在，报道的电流比已经太小，有任何实际意义。上述发现克服了这一缺陷，并且该提议的实验挑战性目标是在作为超薄膜和最终单分子器件进行研究时增强分子二极管的性能。它将尝试通过（i）优化空间位阻Au/D-桥-D*-桥-A/Au和Au/D-桥-A*-桥-A/Au结构中的整流供体-受体序列，其中，电活性组分代表较弱的电活性组分，以及（ii）开发涉及单个分子或小分子簇在纳米尺寸的金电极间隙上的制造后自组装的非侵入性接触技术。目的是利用迄今为止的发现，在+/-1 V时将整流比提高到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.