Influence of Order and Disorder on the Photogeneration of Charge Carriers

该项目(有序和无序对载流子光产生的影响)研究了潜在的半结晶共轭PPE-PPV共聚物的化学侧链结构对富勒烯衍生物(如PCBM)施主-受主主体异质结中聚合物构象有序性的影响。申请者已经在这一材料体系的一些代表性共聚物方面拥有10年以上的经验。这类材料的某些代表的性能至少可以与聚(3-己基噻吩基)(P3HT)相媲美。由于PPE-PPV与富勒烯衍生物的相互作用可以改善聚合物的有序性，而P3HT的有序性在与PCBM共混时会发生扭曲。此外，这种材料体系的优点是，聚合物的构象可以在有序的、半结晶的ANE-PV共聚物和完全无序的、无定形的代表之间精细地调节，仅通过选择-分别取代-溶解性诱导侧链。此外，不需要像P3HT那样，为了获得良好的光电性能而改善与PCBM共混物中富聚合物相的有序性。通过混合这种具有不同有序度的共聚物，从而对PCBM进行溶解，这些材料的光电性能有很大的变化空间。在本项目中，我们将使用系统的合成方法来优化这方面的体系。量子化学计算一方面将通过预测共聚物的二级结构/构象来补充合成努力，另一方面通过测定聚合物和聚合物-富勒烯络合物的UV/VIS光谱，包括通过跃迁和电荷差密度来分析跃迁的电子结构。此外，材料体系将根据聚合物中的有序性程度来实验研究载流子的光产生。应该指出的是，一般来说，聚合物存在于两个不同构象的不同相中：1)在富含聚合物的微晶中；2)在富富勒烯相的界面处，存在于相当无定形的聚合物-富勒烯共混相中。在此基础上，我们的目标是加深对聚合物和富勒烯界面结构的理解，最后揭示富勒烯衍生物的体相异质结中的聚合物构象对电荷传输和复合的影响。我们的目标是基于超快光谱(电荷产生和复合)，太阳能电池器件(电荷产生和复合)以及空间电荷限制电流(SCLC)二极管来研究电荷传输(电荷载流子迁移率)来定量回答这个问题。

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).