Influence of Order and Disorder on the Photogeneration of Charge Carriers

该项目（有序和无序对电荷载体光生作用的影响）研究了潜在半结晶共轭PPE-PPV共聚物的化学侧链结构对聚合物与富勒烯衍生物（例如PCBM）的供体-受体本体异质结内的构象顺序的影响。申请人已经具有超过10年的使用该材料体系的一些代表性共聚物的经验。这种材料类别的一些代表的性能至少与聚（3-己基噻吩）（P3 HT）的性能相当。虽然PPE-PPV与富勒烯衍生物的相互作用可能导致聚合物有序性的改善，但在与PCBM的非退火共混物的情况下，P3 HT的有序性变得扭曲。此外，这种材料体系的优点是聚合物构象可以在有序的AnE-PV共聚物的半结晶形式和完全无序的AnE-PV共聚物之间进行微调，无定形代表仅通过选择-分别取代-诱导溶解度的侧链。此外，不需要退火过程来改善具有PCBM的共混物的富聚合物相中的有序性，以获得良好的光电性能，如在P3 HT的情况下所需的。通过混合具有不同有序度的这样的共聚物，因此对于PCBM的溶解度不同，这些材料的光电性质有很大的变化空间。在本项目中，我们将使用一种系统的合成方法来优化这方面的体系。量子化学计算将一方面通过预测共聚物的二级结构/构象，另一方面通过测定聚合物和聚合物-富勒烯复合物的UV/维斯光谱来补充合成工作，包括通过跃迁和电荷差密度分析跃迁的电子结构。此外，还应根据聚合物内的有序程度，对材料系统的光生载流子进行实验研究。应当提及的是，通常聚合物以不同构象的两种不同相存在：1）以富含聚合物的微晶存在，和2）在与富含富勒烯的相的界面处以相当无定形的聚合物-富勒烯共混物相存在。在此基础上，我们的目标是加深对聚合物与富勒烯之间界面结构的了解，最后揭示聚合物在富勒烯衍生物体异质结中的构象如何影响电荷传输和复合。我们的目标是定量回答这个问题的基础上超快光谱（电荷产生和重组），太阳能电池设备（电荷产生和重组）以及空间电荷限制电流（SCLC）二极管的电荷传输（载流子迁移率）的调查。

The project (Influence of Order and Disorder on the Photogeneration of Charge Carriers) investigates the influence of the chemical side-chain structure of potentially semi-crystalline conjugated PPE-PPV copolymers on the resulting conformational order of the polymer within donor-acceptor bulk heterojunctions with fullerene derivatives (e.g. PCBM). The applicants already have more than 10 years of experience with some representative copolymers of this material system. The performance of some representatives of this material class is at least comparable with that of poly(3-hexylthiophene) (P3HT). While for the PPE-PPV interactions with fullerene derivatives may lead to improved polymer order, the order of P3HT becomes distorted in case of non-annealed blends with PCBM.The advantage of this material system is furthermore that the polymer conformation can be finely tuned between ordered, semi-crystalline versions of the AnE-PV copolymer and completely disordered, amorphous representatives solely by the choice - respectively substitution - of solubility inducing side-chains. In addition, there are no annealing processes required to improve the order in the polymer-rich phase of the blend with PCBM in order to obtain good optoelectronic properties, as required in case of P3HT. By mixing suchcopolymers with different degrees of order and therefore solubility for PCBM, there is much space for variation of the optoelectronic properties of these materials. In the present project we will use a systematic synthetic approach for optimizing the system in this respect.Quantum chemical calculations will complement the synthetic efforts on the one hand by predictions concerning the secondary structure/conformation of the copolymers and on the other hand by determination of UV/VIS spectrum of the polymer and the polymer-fullerene complex, including an analysis of the electronicstructure of the transitions by means of transition and charge difference densities.Furthermore, the material system shall be experimentally investigated in respect of the photogeneration of charge carriers depending on the extent of order within the polymer. It should be mentioned that in general the polymer exits in two different phases of different conformation: 1) in polymer-rich crystallites and 2) in a rather amorphous polymer-fullerene blend phase at the interface to the fullerene-rich phase. Based on that, we aim to develop an improved understanding about the structure of the interface between polymer and fullerene.Finally it shall be revealed how the polymer conformation within a bulk heterojunction with fullerene derivatives influences on charge transport and recombination. We aim for a quantitative answer to this question based on ultrafast spectroscopy (charge generation and recombination), solar cell devices (charge generation and recombination) as well as space-charge limited current (SCLC) diodes for the investigation of charge transport (charge carrier mobility).