Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 45: Organic Thin Films II

DS 45.2: Talk

Friday, March 26, 2010, 12:15–12:30, H8

Use of Phthalocyanines as Photosensitizers for Dye-Sensitized Solar Cells Based on Zinc Oxide — •Melanie Rudolph¹, Jane Falgenhauer¹, Thomas Loewenstein¹, Nkosiphile Masilela², Mopelola Idowu², Tebello Nyokong², and Derck Schlettwein¹ — ¹Institute of Applied Physics, Justus-Liebig-University Giessen, Germany. email:schlettwein@uni-giessen.de — ²Department of Chemistry, Rhodes University, Grahamstown, South Africa

Thin films of porous zinc oxide were prepared by electrodeposition from aqueous precursor solutions containing a structure- directing agent. Phthalocyanines (Pcs) with different central groups and different chemical substituents in the ligand were adsorbed onto the ZnO surface as photosensitizers. The obtained hybrid thin films were investigated with respect to their applicability in dye-sensitized solar cells. Aggregation is known to be a limiting factor for the solar energy conversion efficiency of sensitized semiconductor photoelectrodes, particularly in the case of phthalocyanines. The aggregation behaviour of the adsorbed Pc molecules was therefore analyzed by means of solid state UV/VIS transmission spectroscopy. Different methods were investigated to decrease intermolecular interactions within the photosensitizer layer. The photovoltaic performance of the dye-sensitized electrodes was analyzed by time-resolved photocurrent and photovoltage measurements as well as I(V) characteristics. These results were discussed in context with the aggregation tendency concluded from the UV/VIS data and the position of dye energy levels relative to the conduction band of ZnO.