Plenární přednášky 401 PL01 POLYMERS AND CRYSTALS  A HAPPY MARRIAGE MESOSCOPIC ELECTRODES FOR GENERATION AND STORAGE OF ELECTRIC POWER FROM SUNLIGHT PL03 GLASSES FOR SEEING BEYOND THE VISIBLE

U Graetzel M Bach, D Lupo, P Comte, J Moser, F Weissörtel, J Salbeck, H Spreitzert, M Graetzel
2010 Chem. Listy   unpublished
Biominerals are remarkable materials with complex and often hierarchical structures (see image of sea urchin spine below) and superiour physical properties compared to man made materials made at ambient conditions in aqueous environment. Biominerals are organic-inorganic hybrid materials and the crystallization of the inorganic mineral is highly controlled by organic-usually polymeric additives. The formation processes of Biominerals can be mimicked, which is the field of polymer controlled
more » ... tallization or bio-inspired mineralization. Polymers can have different and often multiple roles in a crystallization process. They can be a scaffold for mineral formation, complex ions, inhibit or enhance crystal nucleation, stabilize amorphous precursor faces, selectively adsorb on crystal faces changing their morphology, encode self organization of nanoparticles and many more. Examples for the various roles of polymers in crystallization processes to generate crystals with complex structures are given. Especially coding of nanoparticles by polymers for subsequent tailored aggregation of nanoparticles is an attractive new research field summarized as Nonclassical Crystalli-zation. This crystallization path is based on nanoparticles instead of ions, atoms or molecules and offers new possibilities for the formation of crystals. These possibilities will be discussed too. Microstructure of a sea urchin spine (Scanning electron micrograph). Although the spine has the properties of a single crystal, its morphology exhibits no crystal faces which are typical for single crystals. The lecture covers our recent research on mesoscopic electrodes that made up of a network of nanometer-sized particles such as titanium dioxide, zinc oxide, tungsten trioxide, Fe 2 O 3 or LiMnPO 4. The pores between the particles are filled with an electrolyte or p-type semiconductor, in this way inter-penetrating bicontinuous network composites are formed which are phase-separated by a hetero-junction. Electrons can percolate rapidly across the network of nanoparticles allowing the huge junction area to be addressed electronically. Intriguingly , cross surface electron and hole transfer in self-assembled monolayers (SAM) of redox-active molecules has also been observed. These mesoscopic oxide electrodes show great promise for a number of applications, such as high power lithium insertion batteries photo-electrochemical cells for solar hydrogen generation and dye-sensitized solar cells (DSCs). The DSC achieves currently a conversion efficiency of over 11 percent and exhibits excellent long term stability, rendering it a credible alternative to conventional silicon based devices. These new cells offers opportunities for applications in building integrated photovoltaic device and light weight solar power supplies. Recently large-scale production of flexible DSC modules has started. REFERENCES 1. O'Regan B.
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