Near IR sensitization of polymer/fullerene solar cells: controlling the morphology and transport in ternary blends

三元体异质结复合材料的设计和开发需要对有机半导体和光致发光的三个独立方面和基本课题进行研究。合成：该项目将从用于传输基质以及敏化剂的可用聚合物开始，然后快速转向为近红外敏化目的定制的新型聚合物，即具有各种带隙和HOMO位置的较小变化。2.形貌：三元BHJ复合材料的形貌评估和形貌控制将是本项目的另一个挑战。不能完全互溶的聚合物（这是常见的情况）在溶液和固体状态下都会表现出分层。根据Hildebrandt，如果聚合物具有相当的分子间粘附力，则它们彼此是可混溶的。我们理解和研究三元体系中的相分离机制将基于类似于汉森理论的方法。通过评估各个组分的溶解度参数，我们研究了三元复合物的汉森球.输运和电荷转移：二元BHJ复合材料中的输运已经是一个复杂的过程。在这个项目中，我们将研究在三元复合材料的传输机制。具体来说，我们将探索合适的实验方法，允许区分两种聚合物的作用和它们各自对空穴传输的贡献。与传输同样重要的是三元共混物中的电荷产生过程。时间分辨泵浦-探测光谱在纳秒制度将被用来了解这两种聚合物如何相互作用。最重要的是，我们想弄清楚这两种聚合物是否可能表现出直接的电荷转移、能量转移，甚至没有电子相互作用。

The design and development of ternary bulk heterojunction (BHJ) composites requires the investigation of three separate aspects and fundamental topics of organic semiconductors and photovoltaics.1. Synthesis: The project will start with available polymers for the transport matrix as well as for the sensitizers, and then quickly move over to novel polymers, customized for the purpose of near IR sensitizing, i.e. with various bandgap and smaller variations in the HOMO position.2. Morphology: The morphology assessment and morphology control of ternary BHJ composites will be another challenge in this project. Polymers which are not completely miscible to each other (and that is the common situation) will show demixing in solution as well as in the solid state. Following Hildebrandt, polymers are miscible to each other if they have comparable intermolecular adhesion forces. Our access to understand and investigate the phase separation mechanisms in ternary systems will be based on an approach similar to Hansen theory. By assessing the solubility parameters for the individual components we investigate the Hansen sphere for a ternary composite.3. Transport and Charge Transfer: Transport in binary BHJ composites is already a complex process. Within this project we will investigate the transport mechanisms in ternary composites. Specifically, we will explore suitable experimental methods which allow to distinguish between the role of the two polymer and their individual contributions to the hole transport. As important as transport is the charge generation process in the ternary blends. Time resolved pump-probe spectroscopy in the ns regime will be used to understand how the two polymers interact with each other. Most importantly, we want to clarify whether the two polymers may show direct charge transfer, energy transfer, or even have no electronic interactions.