Functional Photo-electrochemical Devices for Solar Cellsand Solar Fuels Based on Molecular Components

Sammanfattning: This thesis concerns the development and the study of molecular functional photo-electrochemical cells (PEC) for solar cells and solar fuels.The first chapter gives a general introduction about photosynthesis, dye-sensitized solar cell and photo-electrochemical device for water splitting.The second chapter describes a TiO2-Co-catalyst electrode manufactured by a direct photo-deposition method. The electrode showed activity for electrochemical water oxidation in an electrochemical device.In the third chapter, a photo-electrochemical cell (PEC) with two-electrodes for visible light driven water splitting has been successfully demonstrated. One electrode was a photo-anode, which assembled a ruthenium water oxidation catalyst (complex 1) into a dye-sensitized porous nanostructured TiO2 electrode by employing a cation-exchange membrane (Nafion). The other electrode was platinum which was used as a passive cathode for proton reduction.In the fourth chapter, an earth abundant metal complex with an anchoring group (cobalt complex 2) was synthesized and investigated as water oxidation catalyst. This complex was further applied into a photo-anode in a PEC. The photo-anode was assembled by co-sensitization of complex 2 to a dye-sensitized porous nanostructured TiO2 electrode. The PEC device gave ca. 250 υA/cm2 photo-current and 7.2 % IPCE without applying any bias voltage, which is much higher than the reported results in the sample type of PEC. Meanwhile, we have shown that the catalytic effect is not from free cobalt ions, CoOx film or nanoparticles formed in situ by using complex 2 in the device.The last two chapters describe an optimization of the NiO films prepared in two steps rather than one step film and applied in p-type DSSCs. This optimized film could adsorb more dye (P1), leading to a significant light harvesting efficiency (LHE) and IPCE in DSSCs. We further combined this P1 sensitized photo-cathode with a hydrogen evolution catalyst (complex 3) and applied this photo-cathode into a PEC for visible light hydrogen evolution.