NIRT: Nanoscale Molecular Opto-Electronics

0103175LindsayThis proposal was submitted in response to the situation“Nanoscale Science and Engineering”（NSF 00-119）. 它汇集了有机光化学专家，实验和理论物理学家和工程师在大学（亚利桑那州立大学）-工业（摩托罗拉）合作，旨在开发基于光合电子转移范例的纳米级分子光电器件。该项目的第一阶段建立在PI目前对分子电子器件基本构建模块的工作基础上。他们将使用双功能化分子，一端共价键合到涂金的导电AFM针尖上，另一端共价键合到金基底上。通过这种方式，他们将在单分子水平上测量简单分子绝缘体（正构烷烃）和分子导线（类胡萝卜素）的电学性质。这些测量将与第一原理模拟进行比较，目标是发展理论和实验，直到它们对分子及其与金属电极的接触中的传输有相当准确的描述。有了这些信息，他们将把分子插入氧化硅晶片上金电极的纳米级间隙中。这些设备将在摩托罗拉制造。最后的间隙制造使用了电化学沉积的主动反馈控制，这是一种由该小组的顾问开发的技术。这一步骤的目标是（1）在晶片上制造两个电极器件，这些器件可以根据单分子AFM数据进行表征，（2）探索这些器件的电流-电压特性，其灵活性比AFM更大第二阶段将侧重于光学激发分子和高能电荷分离态分子的电子特性。使用光来为分子尺度的电子器件提供额外的输入提供了几个优点，并且可能为设计和制造技术上有用的结构开辟道路。他们将使用与上面概述的方法大致相同的方法，但是增加了发色团的受控光学激发。他们将从类胡萝卜素开始，作为最简单的系统，但将继续研究含有卟啉和富勒烯的分子，这些分子可以转变为长寿命的三重态或长寿命的电荷分离态。这些系统提出了理论和实验上的挑战，他们提出了计算方法来处理激发或充电时的核弛豫，以及处理高度相关的分子电子态。他们提出了一种单分子光电开关作为候选器件，以集中该小组的长期努力。该装置可能被证明是有用的光电分子级积木。但是，发展科学和技术，将进入建立设备和理解它是这个项目的主要动机。这个小组提供了一个非凡的机会，培训少数民族学生在多学科方法纳米科学在学术和工业研究环境。

0103175LindsayThis proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 00-119). It brings together experts in organic photochemistry, experimental and theoretical physicists and engineers in a University (Arizona State)-Industry (Motorola)collaboration aimed at developing nanoscale molecular optoelectronic devices based on paradigms from photosynthetic electron transfer.The first phase of the project builds on the PIs' current work on the basic building blocks of molecular electronic devices. They will use bifunctionalized molecules covalently bonded at one end to a gold-coated conducting AFM tip and at the other end to a gold substrate. In this way they will measure the electrical properties of simple molecular insulators (n-alkanes) and molecular wires (carotenoids) at the single molecule level. These measurements will be compared to first-principles simulations, with the goal of developing both theory and experiment until they have a reasonably accurate description of transport in both the molecules and their contacts to the metal electrodes. Armed with this information, they will insert the molecules into nano-scale gaps in gold electrodes on oxidized silicon wafers.These devices will be made at Motorola. Final gap fabrication uses active-feedback control of electrochemical deposition, a technique developed by a consultant to the group.The goals of this step are to (1)make two electrode devices on wafers that can be characterized in terms of the single-molecule AFM data and (2) explore the current-voltage characteristics of these devices with greater flexibility than possible in the AFM (for example, making temperature-dependent measurements).The second phase will focus on the electronic properties of optically excited molecules, and molecules in high-energy charge-separated states. The use of light to provide additional inputs to molecular-scale electronic devices offers several advantages, and may lead the way to the design and fabrication of technologically useful constructs. They will use much the same approach as outlined above, but with the addition of controlled optical excitation of chromophores. They will start with the carotenoids, as the simplest system, but will go on to study molecules containing porphyrins and fullerenes that are built to make transitions into long-lived triplet states, or into long-live charge-separated states. These systems present theoretical as well as experimental challenges, and they propose computational approaches for dealing with nuclear-relaxation on excitation or charging and for dealing with highly correlated molecular electronic states.They propose a single-molecule opto-electronic switch as a candidate device on which to focus the long-range efforts of the group. The device might prove useful as an optoelectronic molecular-scale building block. But developing the science and technology that would go into building the device and understanding it are the main motivation for this project.This group provides an extraordinary opportunity for training minority students in multidisciplinary approaches to nanoscience in both academic and industrial research environments.