Photophysics of Conjugated Polymer Thin Films and Semiconducting Single-Walled Carbon Nanotubes

技术摘要：材料研究部和化学部为该奖项提供资金。该奖项支持关于(1)共轭聚合物薄膜和(2)半导体单壁碳纳米管的光物理的理论和计算研究和教育。在(1)中，PI旨在了解(A)单组分聚合物以及(B)由聚合物混合组成的异质结构中的电荷产生机制。PI将研究形态和链间相互作用的作用，并发展一种同时描述激子、激子和激基络合物以及自由和束缚极化子对的理论。在单组分聚合物中，PI旨在解决关于光学阈值附近薄膜中极化子衍生态的起源的古老争议。PI假设在存在显著的链间相互作用的情况下，光激发导致分支，并直接产生极化子对状态。PI将在简化的模型上进行计算来支持这一关键思想，并提出进一步的详细计算。在聚合物共混物中，PI指出，通过电荷转移产生的链间激子的结合能或电荷产生的波长依赖关系不能在简单的智慧中理解，即带偏移大于链内激子的结合能。单组分体系的计算将扩展到混合体系。在(2)中，PI有两个大的目标。第一个是对手性富集型特定纳米管进行的非线性和调制光学光谱实验的定量理解。PI的目的是定量地理解(A)低能暗激子的能量学，(B)半导体纳米管中的Aharonov-Bohm效应和磁光光谱中振荡强度从亮激子到暗激子的传递，(C)横向于纳米管轴的光吸收，以及(D)电吸收。第二个目标是开发复杂的理论和计算技术，以了解高能激子甚至多激子的物理学。参与该项目的研究生和博士后研究员将在物理、化学和光学方面获得经验。一名本科生也将参与这项研究。令人兴奋的新研究成果将被纳入一门跨学科的研究生课程。P.I.作为导师参与了亚利桑那州韦尔的Cienaga高中的学生退出项目。此外，计划每年在同一所高中举办一到两次关于科学职业的演讲。P.I.还参加了一个两国光学联盟，该联盟涉及与墨西哥各研究所的科学家和学生交换信息。将继续与印度科学家开展现有的国际合作。与来自印度和意大利的科学家的新的国际合作正在启动。非-技术摘要：材料研究司和化学司为该奖项提供资金。该奖项支持试图了解光如何与纳米结构，特别是大分子和碳纳米管相互作用的理论和计算研究和教育。PI利用计算机模拟和理论在微观层面上获得洞察力。这些纳米结构中的电子之间的相互作用可能非常强，并导致新的效应、新颖的微观过程或不寻常的光学性质。在过去的二十年里，共轭聚合物和分子已经从实验室的奇特之处演变成了关键的新光学材料。该奖项支持的工作是涉及凝聚态物理和材料化学的跨学科工作。它为纳米电子学、计算和纳米结构材料的新技术的出现提供了智力基础。从事该项目的研究生和博士后研究员将在物理、化学和光学的界面上获得经验。一名本科生也将参与这项研究。令人兴奋的新研究成果将被纳入一门跨学科的研究生课程。P.I.作为导师参与了亚利桑那州韦尔的Cienaga高中的学生退出项目。此外，计划每年在同一所高中举办一到两次关于科学职业的演讲。P.I.还参加了一个两国光学联盟，该联盟涉及与墨西哥各研究所的科学家和学生交换信息。将继续与印度科学家开展现有的国际合作。与来自印度和意大利的科学家的新的国际合作正在启动。

TECHNICAL SUMMARY:The Division of Materials Research and the Chemistry Division contribute funds to this award. This award supports theoretical and computational research and education on the photophysics of (1) thin films of -conjugated polymers, and (2) semiconducting single-walled carbon nanotubes.In (1), the PI aims to understand the mechanism of charge generation in thin films of (a) single-component polymers as well as (b) heterostructures consisting of polymer blends. The PI will investigate the roles of morphology and interchain interactions, and develop a theory that will describe simultaneously excitons, excimers and exciplexes, and free and bound polaron pairs. In the single-component polymers the PI aims to resolve an old controversy regarding the origin of polaron-derived states in thin films near the optical threshold. The PI hypothesizes that photoexcitation in the presence of significant interchain interactions leads to branching and generates a polaron-pair state directly.The PI will perform calculations on simplified models to support this key idea and propose further detailed calculations. In the polymer blends the PI notes that the binding energy of the interchain exciton generated by charge-transfer or the wavelength dependence of the charge generation cannot be understood within the simple wisdom that the band offset be larger than the binding energy of the intrachain exciton. Calculations for the single-component systems will be extended to the blends.In (2) the PI has two broad goals. The first is to reach quantitative understanding of the nonlinear and modulation optical spectroscopic experiments that are being performed for chirally enriched specific nanotubes. The PI aims to quantitatively understand (a) the energetics of the low-energy dark excitons, (b) the Aharonov-Bohm effect in semiconducting nanotubes and the transfer of oscillation strength from the bright to the dark exciton in magneto-optic spectroscopy, (c) optical absorptions polarized transverse to the nanotube axis, and (d) electroabsorpion. The second goal is to develop sophisticated theoretical and computational techniques to understand the physics of higher energy excitons and even multiexcitons.Graduate students and the postdoctoral fellow working on the project will gain experience at the interface of physics, chemistry and optics. An undergraduate student will also be involved in the research. Exciting new research results will be incorporated into an interdisciplinary graduate course. The P.I. participates as a mentor in the Student Exit Project in the Cienaga High School in Vail, Arizona. In addition, one to two presentations per year on careers in science in the same high school are planned. The P.I. also participates in a Binational Consortium in Optics, which involves exchange of information with scientists and students from Institutes in Mexico. Existing international cooperation with scientists in India will be continued. New international collaborations with scientists from India as well as Italy are being initiated.NON-TECHNICAL SUMMARY:The Division of Materials Research and the Chemistry Division contribute funds to this award. This award supports theoretical and computational research and education seeking to understand how light interacts with nanostructures, particularly large molecules and carbon nanotubes. The PI uses computer simulation and theory to gain insight at a microscopic level. The interactions between electrons in these nanostructures can be very strong and lead to new effects, novel microscopic processes, or unusual optical properties. During the past twenty years conjugated polymers and molecules have evolved from laboratory curiosities to key new optical materials. The work supported by this award is interdisciplinary involving condensed matter physics and materials chemistry. It contributes to the intellectual base from which of new technologies for nanoscale electronics, computation, and nanostructured materials may emerge.Graduate students and the postdoctoral fellow working on the project will gain experience at the interface of physics, chemistry and optics. An undergraduate student will also be involved in the research. Exciting new research results will be incorporated into an interdisciplinary graduate course. The P.I. participates as a mentor in the Student Exit Project in the Cienaga High School in Vail, Arizona. In addition, one to two presentations per year on careers in science in the same high school are planned. The P.I. also participates in a Binational Consortium in Optics, which involves exchange of information with scientists and students from Institutes in Mexico. Existing international cooperation with scientists in India will be continued. New international collaborations with scientists from India as well as Italy are being initiated.