Molecular Design of Metal Complexes and Coadsorption Materials for Panchromatic and Highly Efficient Dye-Sensitized Solar Cells( I )

Searching for new materials, device fabrication and performance characterization are crucial to the commercialization of photovoltaic (PV) technologies. Dye-sensitized solar cells (DSCs) are one of the promising new-generation PVs devoted to outdoor and indoor applications in virtue of the semi-transparency, colorfulness, flexibility, impressive power conversion efficiency, good stability, easy scaling-up process and low manufacturing cost. In the DSCs, photosensitizers self-assembled onto the surface of mesoporous metal oxides (such as TiO2 and ZnO) not only serve as the photon-to-electricity conversion centers, but also play vital roles in power conversion efficiency and durability of the devices. Molecular design of ruthenium and osmium complex photosensitizers coordinated with polypyridyl ligands for the applications in DSCs is the core of this research project, not only to reinforce the light-harvesting ability of visible and near-infrared photons, but also for more and deeper understanding of the ligand and metal effects on the properties of coordination complexes. To gain insights into the spin-allowed singlet metal-to-ligand charge transfer (MLCT) and spin-orbit coupling (SOC) induced triplet MLCT transitions, molecular simulation based on the time-dependent density functional theory (TDDFT) will be carried out. Furthermore, the impacts of various phosphine ligands and counteranions on the metal complexes and device performance will be individually studied to advance the molecular-engineering of coordination complexes. On the other hand, multi-functionalized coadsorbents will be developed to reduce dye aggregation, passivate TiO2 surface, uplift the quasi-fermi level of TiO2, and increase light absorption capability of the devices. The device fabrication conditions will be optimized to demonstrate the potential of new materials. The new results of this project can provide more and clearer clues to the material innovation for panchromatic and highly efficient DSCs.