Control of the nanoscale morphology of bulk heterojunction solar cells via chemical assembly of low bandgap conjugated polymers on nanoparticle support

该项目的重点是了解接枝到纳米粒子上的共轭聚合物（CP）的共价预组织如何影响其光伏（PV）特性。使用Dresden小组新开发的表面引发Kumada缩聚反应，将合成两个系列的具有系统可变接枝密度的具有低带隙共聚物壳的毛状纳米颗粒，所述低带隙共聚物壳含有二噻吩并[3，2-B：2 '，3'-d]噻咯供体单元和苯并噻二唑或萘二酰亚胺受体单元。溶液处理的太阳能电池将在RiskoreDTU由两种毛状颗粒与PCBM结合制备。将系统地研究接枝密度对PV性能的影响;将结果与相应的线性CP的性能进行比较。我们的“预组织”方法的固有优点是，从表面通过同时聚合形成的链自动地呈现为彼此平行地堆叠和拉伸，这应该有利于电荷和能量传输，即使在典型的无定形无规共聚物的情况下。此外，精细工程的内部组成的毛状颗粒，如准备所需的梯度和定位的各种功能在颗粒的外围，应该是直截了当的与我们的接枝从方法，这是一个新的和潜在的强大的工具，在自组装，电荷分离和电荷重组过程的调节。

The project focuses on understanding of how covalent preorganization of conjugated polymers (CPs) grafted to nanoparticles affects their photovoltaic (PV) properties. Using surface-initiated Kumada polycondensation newly developed in the Dresden group, two series of hairy nanoparticles with systematically variable grafting density having low bandgap copolymer shell containing dithieno[3,2-b:2’,3’-d]silole donor units and benzothiadiazole or naphthalene diimide acceptor units, will be synthesized. Solution-processed solar cells will be prepared from the two kinds of hairy particles in combination with PCBM at the Risø DTU. The influence of the grafting density on PV properties will be systematically investigated; the results will be compared with the performance of the corresponding linear CPs. An inherent advantage of our “preorganization” approach is that the chains formed by simultaneous polymerization from the surface automatically appear to be staked parallel to one another and stretched, which should favor charge and energy transport even in the case of typically amorphous random copolymers. Further, a fine engineering of the internal composition of the hairy particles, such as preparation of desired gradients and positioning of various functions at the periphery of the particles, should be straightforward with our grafting-from approach that is a new and potentially powerful tool in regulation of self-assembly, charge-separation and charge-recombination processes.