Revelation of Structure-Property Relationships of Polymers Using Molecular Simulation

与化石燃料生产能源有关的环境问题和飙升的原油价格一直是发展可再生能源的主要刺激因素。事实上，一小时阳光照射在地球上的能量超过了人类一整年所消耗的能量，而找到一种合适的方式来捕捉这种形式的能量肯定可以永远解决人类对能源的担忧。80年代初有机半导体的出现使用聚合物制造太阳能电池成为可能。这些所谓的塑料太阳能电池的优势包括重量轻、化学结构的多功能性、机械灵活性和易于加工(价格低廉)。然而，仍然有两个主要障碍需要克服，它们是电力转换效率(~8.3%，最新报道的值)和耐用性(~1年)。预计10%或更高的效率和大约10年的设备寿命将使这项技术在商业上可行。最近，各种研究人员的初步结果表明，共轭双嵌段共聚物可能有助于克服第一个障碍，因为这类材料显示出高功率转换效率所需的各种可控纳米级形态。为了同时解决电力转换效率和耐用性问题，我建议使用多个三嵌段共聚物。基本思想是，除了具有所需电子性能的两块三嵌段共聚物外，第三块将对电极和/或传输层具有很强的亲和力，并能够降低氧和水的扩散系数，这两种化合物被认为会导致聚合物太阳能电池中有源层的退化。使用多个三嵌段共聚物将使太阳能电池吸收最大部分的入射阳光。特别是，我将应用分子模拟技术来研究各种三嵌段共聚物的结构-性能关系。预计在拟议的工作中产生的见解将使我们能够更好地设计聚合物太阳能电池。

Environmental issues related to energy production from fossil fuels and soaring crude oil prices have been the main stimulants for the development of renewable energy resources. In fact, energy from one hour of sunlight striking on Earth is more than all of the energy consumed by mankind in an entire year and finding a suitable way to capture this form of energy could definitely solve energy concerns of the human race forever. Advent of organic semiconductors in the early 80s made it possible to fabricate solar cells from polymers. The advantages of these so-called plastic solar cells include lightweight, versatility of chemical structure, mechanical flexibility and ease of processing (inexpensive). However, there are still two major hurdles that need to be overcome and they are the power conversion efficiency (~ 8.3%, latest reported value) and durability (~ 1 year). It is expected that efficiencies of 10% or higher and device lifetimes of around 10 years will make this technology commercially viable. Most recently, preliminary results of various researchers have shown that conjugated di-block copolymers may help overcome the first hurdle as such materials exhibit a variety of controllable nano-scale morphology needed for high power conversion efficiency. To address both the power conversion efficiency and durability issues, I propose to use multiple tri-block copolymers. The basic idea is that beside the two blocks of the tri-block copolymers having the desired electronic properties, the third block will have strong affinity for the electrodes and/or transport layer and the ability to reduce the diffusivity of oxygen and water, the compounds that are believed to cause degradation of the active layer in polymer solar cells. Use of multiple tri-block copolymers will make the solar cell to absorb maximum portion of incident sunlight. In particular, I will apply molecular simulation techniques to study structure-property relationship of various tri-block copolymers. It is expected that insights generated in the proposed work will allow us to better design polymer solar cells.