Collaborative Research: NSF-BSF: Understanding Semiconducting Polymers in High-Dielectric-Constant Environments

非技术综述：对塑料半导体的研究导致了可以收集太阳能并将其转化为电能的材料。然而，目前用这种半导体塑料制造的设备很复杂，需要两种材料才能有效地将光转换为电能。目前的项目探索这种结构最终是否可以简化，可能会产生基于单一材料的器件。为此，将使用模型系统系统地研究局域环境对塑料半导体的电子和光学性质的影响，以测试预测通过使塑料半导体的局域环境更极性可以制造更高效的器件的理论。在这个项目中取得的基本见解将允许设计和生产新的塑料半导体，提高基于塑料的太阳能电池的效率和潜在的稳定性，并可能简化它们的生产，最终可以像印刷报纸一样印刷它们。这些都是提高塑料半导体在一系列应用中的经济可行性的因素，反过来，将有助于减少温室气体排放，并促进基于太阳能电池集成到温室中的零能耗住房和低水密集型农业等概念的实施。技术摘要：计划中的工作旨在显著提高我们对高-K环境如何影响聚合物半导体光电性能的基本理解。虽然功能聚合物的有效介电常数k可以通过化学设计或聚合物的周围环境来控制，但分子结构的变化也会影响其他特性，包括极性、分子堆积、相行为和电子性质。因此，到目前为止，很少有直接的结构/功能关系在实验上建立起来。在这个项目中，目前阻碍结构/功能相互关系的各种复杂因素将通过i)在加工过程中尽可能地将聚合物自组装与高k材料的引入分开，以允许在比较之前/之后的清洁，以及ii)寻求新的自组装策略来创建分子杂化材料和混合物，从而绕过目前各种阻碍结构/功能相互关系的复杂因素。这些方法允许调整自组装的长度尺度和特定的界面区域，进而提供了将受欢迎的光电效应与可能影响光电性能/材料性能的其他因素分开的方法。在该项目中获得的知识将应用于聚合物太阳能电池，这通常依赖于施主：受主体异质结来实现有效的激子分裂。该项目的一个主要目标是勾勒出是否存在通过修改相关半导体聚合物主干附近的k来显著降低激子结合能(从而实现有机太阳能电池中有效的激子分裂)的途径，或者是否确实需要修改主干本身。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Research into 'plastic' semiconductors has led to materials that can harvest the energy of the sun and convert it into electricity. Yet, current devices made with such semiconducting plastics are complex and require two materials to efficiently convert light into electricity. The current project explores whether eventually this structure could be simplified, possibly yielding devices based on a single material. For this, the effect of the local environment on the electronic and optical properties of the plastic semiconductor will be systematically investigated using model systems to test theories that predict that more efficient devices could be produced by making the local environment of the plastic semiconductor more polar. The fundamental insight achieved in this project will allow to design and produce new plastic semiconductors, improve the efficiency and potentially the stability of plastic-based solar cells, and will likely simplify their production so that they eventually could be printed similar to the way newspapers are printed. These all are factors that would improve the economic viability of plastic semiconductors in a range of applications and, in turn, would contribute to reduced greenhouse gas emission and facilitate implementation of concepts such as zero-energy housing and low-water-intensity farming based on solar cell integrations into greenhouses.TECHNICAL SUMMARY:The planned work aims to significantly advance our fundamental understanding of how high-k environments affect the optoelectronic properties of polymer semiconductors. While the effective dielectric constant, k, of functional polymers can be manipulated via chemical design or the surrounding of the polymer, changes in molecular structure to create a high-k polymers also affect other features, including polarity, molecular packing, phase behavior, and electronic properties. As a consequence, few direct structure/function relations have been experimentally established to date. In this project, various current complications that have hindered the delivery of structure/function interrelations will be circumvented via i) separating the polymer self-assembly during processing from the introduction of the high-k material as much as possible, to allow for a clean before/after comparisons, and ii) pursuing new self-assembly strategies to create molecular hybrid materials and blends. These approaches allow to tune the lengthscales and specific interfacial areas of the self-assembly and, in turn, provide means to disentangle sought-after optoelectronic effects from other factors that might impact optoelectronic properties/materials performance. The knowledge gained during the project will be applied to polymer solar cells, which generally rely on donor:acceptor bulk heterojunctions to achieve efficient exciton splitting. A main goal of the project is to delineate if there is ever a pathway to significantly lower the exciton binding energy (and thus realize efficient exciton splitting in organic solar cells) by modifying k in the vicinity of relevant semiconducting polymer backbones or if one really needs to modify the backbone itself.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.