Characterisation and rational design of porous conjugated polymers for solar energy conversion

点击翻译按钮获取中文摘要

Conjugated microporous polymers (CMPs) have exciting applications as sensors, emitting diodes but also as potential materials for transforming solar energy to either electricity for direct use or to chemical fuels such as hydrogen for energy storage, the chemical fuel could be transformed to electricity in a later stage. I propose to concentrate on these last two applications that have the potential to accelerate the energetic transition to "low-carbon" energies due to the possible high availability and low costs of those materials.CMPs are formed of building blocks ("bricks") that are assembled into complex 3D skeletons that form nanoparticles ("houses"). These "houses" will have different shapes and depending on the shape, be more or less functional. The "houses" can in turn interact and assemble into a "city". In the same way as "houses" can present larger or smaller volumes and "cities" can be more or less dense, CMPs can have a broad distribution of pore sizes. Ultimately, the way "houses" are organised and connected will impact transport and efficiency of the "city". Similarly, CMPs 3D skeleton and pore network will impact photo-electrochemical properties and device efficiency.The chemical design of the elemental "bricks" is almost infinite and thus, their combinations impossible to screen by trial and error method. Furthermore, synthesizing some combinations might be a real challenge or even impossible. Therefore, chemical intuition is what ultimately guides synthetic chemists. However, even in state-of-the-art labs, synthesizing new CMPs, and then characterizing them is a slow process. In this fellowship, I propose to develop a computational screening tool that can be used complementary to combinatorial chemistry to speed up materials discovery. Reaching the prediction stage within the time of the fellowship would be over-optimistic but defining a set of new design rules to guide synthesis of new CMPs can be achieved. The computational tool will aim to link chemical design with electronic properties of the material. All the structural properties of CMPs have to be grasped by the computational tool. In order to answer the challenge, different computational techniques will have to be combined in a multiscale modelling scheme where parameters for the larger scale model are extracted from the shorter scale model Such models must be experimentally validated to be useful for calculating photo-electrochemical properties. CMPs are built in a random manner and possess no long-range order. Thus, structural characterization is challenging. Part of the project is therefore dedicated to the validation of the model by a combination of spectroscopic techniques.CMPs are so far insoluble and thus processing them into thin film is challenging. Thin films would be ideal for the applications I want to investigate and would further enable optical and electrical characterization. I propose to further investigate processing routes to thin films from this insoluble CMPs as well as using my computational tool to propose new chemical design for soluble CMPs.