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Molecular-Level Approaches to Photosensitive Nanostructured Materials: A Combined Theoretical and Experimental Study of Ultrafast Energy and Charge Transfer

光敏纳米结构材料的分子级方法：超快能量和电荷转移的理论与实验相结合的研究

基本信息

批准号：
209000113
负责人：
Professorin Dr. Irene Burghardt
金额：
--
依托单位：
Institut für Physikalische und Theoretische Chemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/209000113?language=en
关键词：
Molecular Level Approaches Photosensitive Nanostructured

项目摘要

This project is concerned with the molecular-level investigation of photoinduced charge generation in perylene diimide (PDI)-based donor-acceptor (DA) block co-oligomer species forming highly ordered lamellar mesophases, which show promise for applications in organic photovoltaics. These DA systems represent the most recent generation of a new class of materials which have been spectroscopically and theoretically investigated during the initial funding period of this project, in the framework of a joint DFG/ANR project with the group of S. Haacke at Strasbourg University. Notably, it was shown in these previous investigations that (i) the first-generation materials show ultrafast charge separation but high recombination rates, which could be explained by the specific molecular packing properties, (ii) the second-generation materials can be chemically tuned, such as to obtain charge transfer states with lifetimes up to a few nanoseconds, and low recombination rates in solution. Against this background, the present follow-up project is devoted to the detailed modeling of the second-generation materials in a highly ordered thin-film morphology. Based upon available structural data as well as new time-resolved spectroscopic studies that are currently underway, we will use a combination of electronic structure and microelectrostatics calculations, quantum dynamical calculations, molecular dynamics simulations, and Kinetic Monte Carlo (KMC) simulations to obtain a detailed picture of the process, from the initial charge separation to long-range carrier transport. A first-principles parametrized lattice Hamiltonian will be constructed using information from electronic structure calculations for suitable fragments, along with a microelectrostatics treatment that accurately describes the local electrostatics including polarization effects. This lattice Hamiltonian provides a unified representation for both quantum dynamical simulations (on the femtosecond to picosecond scale) and KMC simulations (on the picosecond to microsecond scale), and permits a consistent embedding of the dynamical modelling in a multi-scale setting. In this context, high-dimensional quantum dynamical calculations using the Multi-Layer Multiconfiguration Time-Dependent Hartree (ML-MCTDH) method will be typically carried out for more than one hundred electronic states and vibrational modes, to cover a time scale up to tens of picoseconds. A special focus will be placed upon the role of molecular packing, inducing exciton and charge delocalization, along with additional transfer pathways. In particular, PDI stacking is expected to lead to a complex photochemistry of charge separated species, which could tangibly influence the charge generation and transport. The present analysis is expected to quantify the combined effects of chemical composition and molecular packing, providing essential ingredients for the rational design of next-generation DA materials.

本项目关注的是分子水平上的光诱导电荷产生的研究，在？二酰亚胺（PDI）为基础的给体-受体（DA）嵌段共聚低聚物物种形成高度有序的层状中间相，这显示出在有机光致发光应用的前景。这些DA系统代表了最新一代的新材料，在该项目的初始资助期间，在DFG/ANR与S. Haacke在斯特拉斯堡大学。值得注意的是，在这些先前的研究中表明，（i）第一代材料显示出超快的电荷分离，但复合率高，这可以通过特定的分子堆积特性来解释，（ii）第二代材料可以进行化学调节，例如获得寿命高达几纳秒的电荷转移状态，以及溶液中的低复合率。在此背景下，本后续项目致力于第二代材料在高度有序的薄膜形态的详细建模。基于现有的结构数据以及目前正在进行的新的时间分辨光谱研究，我们将使用电子结构和微静电计算，量子动力学计算，分子动力学模拟和动力学蒙特卡罗（KMC）模拟的组合，以获得从初始电荷分离到远程载流子传输的过程的详细图像。一个第一原理参数化晶格哈密顿量将被构造使用合适的片段，沿着与微静电处理，准确地描述了本地静电，包括极化效应的电子结构计算的信息。该晶格哈密顿量为量子动力学模拟（在飞秒到皮秒尺度上）和KMC模拟（在皮秒到微秒尺度上）提供了统一的表示，并且允许在多尺度设置中一致地嵌入动力学建模。在这种情况下，使用多层多组态时间相关哈特里（ML-MCTDH）方法的高维量子动力学计算通常会对一百多个电子态和振动模式进行计算，以覆盖高达数十皮秒的时间尺度。一个特别的重点将放在分子包装的作用，诱导激子和电荷离域，沿着额外的转移途径。特别是，PDI堆叠预计会导致电荷分离物质的复杂光化学，这可能会切实影响电荷的产生和传输。目前的分析预计将量化的化学成分和分子堆积的综合影响，为下一代DA材料的合理设计提供必要的成分。