Dresden 2020 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 84: Poster Session - Solid-Liquid Interfaces: Reactions and Electrochemisty

O 84.4: Poster

Mittwoch, 18. März 2020, 18:15–20:00, P2/EG

Assembly and Characterization of Aqueous Dye-sensitized Solar Cells with Organic Nitroxides as Redox-mediators — •Daniel Holzhacker, Raffael Ruess, and Derck Schlettwein — Justus Liebig University Gießen, Institute of Applied Physics

Dye-sensitized solar cells (DSSCs) present a possible low-cost technology for the conversion of sunlight into electrical energy. The most efficient DSSCs are based on organic cobalt (II/III)-complexes in organic solvents, i.e. acetonitrile. Due to environmental reasons it is attractive to avoid the organic solvents. In view of the damage caused by water contamination in organic electrolytes, replacing acetonitrile by water seems to be a big challenge in DSSC research. Following tests on one or two components, complete aqueous DSSCs were assembled. Using cyclic voltammetry (CV) the diffusion coefficient and the redox-potential of the organic nitroxides in water were determined. For the investigation of the energy levels of the adsorbed dyes, CV and UV/vis-spectroscopy were performed. The cells were based on thin ( 2−3 µ m) screen-printed and annealed titania films, sensitized with different organic dyes (D51, D35 or Y123) overnight. J-V-curves and transient photocurrents of the different types of cells were measured. Power conversion efficiencies up to 4.4 %, which are among the highest reached for aqueous DSSCs so far, could be achieved using the molecule TEMPO as redox-mediator. Its derivates AZADO and TEMPOL showed great potential in photocurrent and open circuit voltage but a limitation in the fill factor indicates the need for further investigations.