Aqueous-Based Dye Sensitized Solar Cells: Copper Electrolytes

Abstract

Nowadays, dye-sensitized solar cells (DSCs) have been a great alternative to the conventional p-n junction photovoltaic devices that convert solar energy to electrical current, especially for indoor applications. However, a DSC to be used as the power source in any indoor appliance, it should be an eco-friendly device. One of the most important components of DSCs is the electrolyte, since it plays a crucial role in the regulation of electron transfer kinetics. The most currently used electrolyte systems are the I-/I3- couple and copper or cobalt complexes dissolved in an organic solvent. The solvent is usually a nitrile based organic compound, where some of which are either toxic or of very high volatility.

In this study, we report on the use of eco-friendly aqueous electrolyte systems that contain one of three highly-charged pyridyl-based aqueous copper complexes (anionic or cationic) with hydrophilic groups such as –OHs and their use in DSCs with different commercially available organic and metal complex dyes. Additionally, these complexes bear two groups on the 6, 6’ positions for the bipyridine-based or 2, 9 for phenanthroline-based complexes that stabilize the Cu (I) state, achieving DSCs with reduced cost, improved environmental compatibility, and having promising efficiencies.

The Ru-based C106 dye sensitizer showed the best photovoltaic performance with the Cu(dmdcbpy)2]2+/1+ based electrolyte, and was further demonstrated to show a remarkable PCE value at ambient lighting for 100% aqueous-based DSCs. Under illumination from a white LED light (1000 lux) we achieved a PCE value of 6.54%.