Applications of nitroxides as redox mediators in dye-sensitized solar cells

Overview

Topic status: We're looking for students to study this topic.

Project Summary

Dye-sensitized solar cells (DSCs) are presently an area of intense academic and industrial interest due to their potential application as a low-cost alternative to existing photovoltaic technologies. In DSCs, there are three main components; a light absorbing sensitizer, a semiconducting metal oxide and an electrolyte. To date, the state-of-the art DSC fabricated by combining a ruthenium dye, an iodine electrolyte, and a thick mesoporous titania film has been shown to have the record solar-to-electricity conversion efficiency of 11.1%. While representing state-of-the-art, one area that could be improved is the electrolyte. The iodine system (I-/I3-) which represents the almost exclusive used redox mediator, suffers from a mismatch between its redox potential and that of common dye sensitizers. The excess energy given off during this cycling is lost to the system and therefore limits the performance of DSC. Substantial investigation has been carried out into finding alternative redox mediators that could be used in place of the iodine system including iron and cobalt based metal complexes and stable organic free radicals species (e.g. piperidine-based nitroxides). At present however, these systems lack the efficiency and stability of the iodine-based electrolyes.  

Fused aromatic nitroxides, such as isoindoline and azaphenalene nitroxides, possess some advantages over the more common nitroxide-containing piperidine or pyrrolidine units. In particular, the fused aromatic moiety imparts rigidity on the ring system, making it less susceptible to ring-opening reactions and providing greater chemical and thermal stability. The presence of an aromatic moiety within the nitroxide’s carbon framework also allows for the addition of further functionality. Recently, through molecular modeling, we have identified a number of reversible nitroxide/N-oxoammonium couples based on isoindoline and azaphenalene nitroxides, that theoretically should have redox potentials much closer to that of most common sensitizers.

Expected outcomes, applications and/or benefits

The above mentioned compounds should give more efficient electron transport from the sensitizer and lead to less inherent energy loss giving an overall more efficient DSC. Synthetic studies to produce a number of these predicted nitroxide targets are required. The potential student would synthesise and evaluate a range of isoindoline and azaphenalene nitroxide/N-oxammonium cation redox couples as potential electrolytes in dye sensitized solar cells. Students will gain synthetic skills in organic chemistry and chromatography and instrumental experience with compound characterisation (NMR, HPLC, MS, IR, fluorescence, UV/vis etc).

Required student skills/experience

Students require an undergraduate GPA of 5.5 or better and should have a minimum of chemistry as a minor within their degree. Interests in organic chemistry (either synthetic or physical organic) would be preferable.

Study level
Vacation research experience scholarship
Supervisors
QUT
Organisational unit

Science and Engineering Faculty

Research area

Chemistry

Keywords
solar, nitroxides
Contact
Contact the supervisor for more information