Investigation of the electronic transport through photochromic molecules under plasmonic excitation Etudes du transport électronique à travers des molécules photochromes sous excitation plasmonique

该联合项目致力于研究与金属导线接触的可光开关分子在光照射下的电子输运特性。它的基础是掌握三个热点问题，即通过金属-分子-金属结电传输的理解，量身定制的开关分子的合成，以及与光辅助传输物理相关的高级等离子体。等离子体色谱仪将结合这些主题，以揭示等离子体共振如何耦合到金属-分子-金属器件，从而旨在通过电极的光学天线效应来提高光致变色分子的开关效率。我们将研究可调谐的单分子结，其中的引线带有优化的格栅，用于激发传播的表面等离子体激元(SPP)。同时，我们将纳米组装两个由几个分子连接的金纳米粒子，并利用先进的扫描探针技术研究局域表面等离子体共振(LSPR)对电荷传输的影响。对于这两种器件的概念，开关效率将作为等离子体激发的函数进行研究。这些研究一方面将揭示一条优化电极等离子体性质的途径，另一方面将为改进双芳基分子的合成和光致变色性能提供指导。二芳基乙烯的功能是基于开环/闭环原理，这有利于器件的应用，因为由于异构化引起的电子变化只伴随着很小的几何变化。主要的预期结果是设计一种具有可重复和高效可调电导的分子电子器件。

The joint project PlasmoChrom is devoted to the study of electronic transport properties of photoswitchable molecules contacted to metal leads under light irradiation. It is based on the mastering of three hot topics, which are the understanding of electrical transport through metal-molecule-metal junctions, the synthesis of tailored switching molecules, and advanced plasmonics related to the physics of photo-assisted transport. PlasmoChrom will combine these topics in order to reveal how plasmonic resonances can be coupled to metal-molecule-metal devices and thereby aim at enhancing the switching efficiency of photochromic molecules by virtue of optical antenna effects of the electrodes. We will investigate tunable single-molecule junctions with leads patterned with gratings optimized for exciting propagating surface plasmon polaritons (SPPs). In parallel we will nano-assemble two gold nanoparticles connected by a few molecules and investigate by advanced scanning probe techniques how localized surface plasmon resonance (LSPRs) affects the charge transport. For both device concepts the switching efficiency will be studied as a function of plasmonic excitation. These studies will reveal on the one hand a route to optimize the plasmonic properties of the electrodes and, on the other hand, provide guidelines for the improvement of the molecular synthesis and photochromic properties of diarylethene-based molecules. The functionality of diarylethenes is based on the ring-opening/ring-closure principle, which is favorable for device applications because the electronic changes due to the isomerization go along with only minor geometrical changes. The main expected outcome is the design of a molecular electronics device with reproducibly and efficiently tunable conductance.