Molecular Understanding of Thermo-Electric Properties in Organic Polymers

任何来自初级能源的能量转换都伴随着热损失。一种有效的和环境友好的方式来重新利用废热是热电。热电转换温差，从而将热转换成电。作为材料性质，它由电导率（s）和热导率（k）以及塞贝克系数（a）确定。热电效率可以用品质因数zT =（sa^2/k）T来量化。最佳热电材料的zT约为1（等于或低于250°C）。低成本、环境友好、可溶液加工和柔性热电模块的新兴候选物是π共轭的半导体聚合物。然而，它们表现出低电导率，导致zT非常低，为10^-5（室温下）。掺杂可以将电导率增加到金属类值，但降低塞贝克系数。 可以通过减少掺杂剂体积和控制聚合物的氧化态来实现最佳平衡，导致zT~1。尽管这一最新进展，仍然没有根本的理解不同的掺杂剂，确定超分子聚合物掺杂剂结构，以及电荷和传热properties.This project is aimed at the molecular understanding of thermal and electrical properties of polymer-dopant blends，using multiscale atomistic simulations.以下属性将被建模为最先进的p型和n型有机热电：1）结构，2）光谱特性，3）电荷传输机制，4）电导率，5）塞贝克系数和6）热导率，以解决掺杂剂和半导体聚合物链之间的相互作用。最终的目标是了解聚合物半导体材料中从分子到微观尺度的热电现象的结构-功能关系。该项目将是第一个系统的分子驱动的研究，结合原子模拟与电荷和热输运理论在（半）导电聚合物和复杂的聚合物掺杂剂共混物。它还将为理解有机自旋电子学和有机电池等新兴技术的物理化学铺平道路。

Any energy transformation from primary sources is accompanied by heat losses. An efficient and environmental friendly way to reutilize the waste heat is thermoelectrics. Thermoelectricity converts temperature differences and thus heat into electricity. As a material property it is determined by the electrical (s) and thermal (k) conductivity and the Seebeck coefficient (a). The thermoelectric efficiency can be quantified with the figure-of-merit zT = (sa^2/k)T. Optimal thermoelectric materials posses a zT of about 1 (at or below 250°C). Emerging candidates for low cost, environmental friendly, solution-processable and flexible thermoelectric modules, are pi-conjugated, semiconducting polymers. However, they exhibit low electrical conductivity, leading to very low zT of 10^-5 (at room temperature). Doping can increase the electrical conductivity up to metallic-like values, but lower the Seebeck coefficient. An optimum balance can be achieved by reducing the dopants volume and controlling the oxidation state of the polymer, leading to zT~1. Despite this recent progress, there is still no fundamental understanding of the effects induced by different dopants that determine the supramolecular polymer-dopant structures, as well as charge and the heat transfer properties.This project is aimed at the molecular understanding of thermal and electrical properties of polymer-dopant blends, using multiscale atomistic simulations. The following properties will be modelled for state-of-the-art p- and n-type organic thermoelectrics: 1) structure, 2) spectroscopic properties, 3) charge transport regimes, 4) electrical conductivity, 5) Seebeck coefficient and 6) thermal conductivity to address the interplay between dopants and semiconducting polymer chains. The ultimate goal is to understand the structure-function relationships that rule thermoelectric phenomena, from the molecular up to the microscopic scale, in polymer semiconductors materials. This project will be the first systematic molecular driven investigation, combining atomistic simulations with charge and thermal transport theories in (semi)conducting polymers and complex polymer-dopant blends. It will also pave the way toward a physical-chemical understanding of emerging technologies such as organic spintronics and organic batteries.