Long range charge transport in Molecular Electronic devices

分子电子学（ME）领域寻求通过将分子结合到电子电路中来提高传统微电子器件的电子功能，以提高性能，降低成本，减少功率需求并提供新颖的电子功能。我们的团队率先开发了一种可靠的、可重复的分子结，具有足够的使用寿命（~年）和耐温性（-260至+300°C），可用于实际应用。这种连接点实现了硅片无法实现的音频处理功能，2014年开发的原型机目前正在评估其在全球音频配件市场上的商业化价值，该市场每年超过20亿美元。在这种装置中，特别重要的是1- 25nm范围内的电子传输机制，这与传统半导体或广泛研究的“有机”电子学中较厚薄膜（> - 50nm）中的传输有着根本的不同。我们计划探索利用分子轨道进行电荷传输的新型传输机制，最终目标是利用分子结构的变化合理地设计新的电子行为。我们已经报道了一个高度依赖于分子结构的电离机制的初步结果，并在5-20纳米的距离上工作，这对于量子力学隧道来说太大了。1-25纳米的传输距离范围不仅避免了“有机电子学”的陷阱，而且还实现了“弹道”传输，可以实现非常高频的工作（>1000 GHz）。我们将利用过去十年中发展起来的坚固的分子结结构来开展三个相关的基本子项目，研究分子结构如何影响电子行为：***项目1：传输的结构控制。具有相似结构但不同能级的噻吩衍生物将在隧道以外的距离范围内（即5-20 nm）进行研究，在那里我们已经观察到轨道能量的强烈影响。我们将研究轨道能量的变化对共振输运、场电离和弹道输运机制的影响。***项目2：双层和三层结。相邻分子层轨道能量的差异预计会引起触点和分子轨道之间的整流和可能的共振。我们将研究轨道能量对输运的影响，以帮助制定分子电子行为的“设计规则”。***项目3：工作分子器件的光学监测。除了通过光谱学验证器件结构外，我们还将研究器件光电流和光发射作为内部能级和弹道输运的探针。***这些项目有可能导致一个全新的微电子类基于分子结具有不同于硅的有价值的功能和行为

The field of molecular electronics (ME) seeks to enhance electronic functions of conventional microelectronic devices by incorporating molecules into electronic circuits to improve performance, lower costs, reduce power demands and provide novel electronic functions. Our group was the first to develop a reliable, reproducible molecular junction with sufficient lifetime (~ years) and temperature tolerance (-260 to +300 °C) for practical applications. This junction enabled an audio processing function not possible with silicon, and a prototype developed in 2014 is currently being evaluated for commercialization in an audio accessory market exceeding $2B/year worldwide. Of particular importance in such devices are the electron transport mechanisms over distances in the 1-25 nm range, which differ fundamentally from the transport in either conventional semiconductors or in the thicker films (>50 nm) in widely studied "organic" electronics. We plan to explore novel transport mechanisms that exploit molecular orbitals for charge transport, with the ultimate objective of rationally designing novel electronic behaviours using variations in molecular structure. We have reported initial results on an ionization mechanism strongly dependent on molecular structure and operative over 5-20 nm, distances too great for quantum mechanical tunneling. A transport distance range of 1-25 nm not only avoids the pitfalls of "organic electronics" but also enables "ballistic" transport, which can enable very high frequency operation (>1000 GHz). We will use the robust molecular junction structure developed over the past decade to pursue three related fundamental subprojects on how molecular structure affects electronic behaviour:***Project 1: Structural Control of Transport. Thiophene derivatives with similar structures but varying energy levels will be investigated in the distance range beyond tunneling (i.e., 5-20 nm), where we have observed strong effects of orbital energies. We will investigate the effects of variations in orbital energies to resonant transport, field ionization, and ballistic transport mechanisms.***Project 2: Bi-layer and Tri-layer Junctions. Differences in orbital energies of adjacent molecular layers are expected to cause rectification and possibly resonance between the contacts and molecular orbitals. We will study the effects of orbital energies on transport to help formulate the "design rules" of molecular electronic behaviour.***Project 3: Optical Monitoring of Working Molecular Devices. In addition to verifying device structures via spectroscopy, we will investigate device photocurrents and light emission as probes of internal energy levels and ballistic transport.***These projects have the potential to lead to an entire new class of microelectronics based on molecular junctions with valuable functions and behaviours distinct from those of silicon.**