Synthesis of phenanthrene-annulated imidazolium electrolyte-based dye sensitized solar cells as redox mediators

Phenanthrene-annulated imidazolium (PAI) compounds are synthesised in this study. These additive-free PAI electrolytes with high conductivity are used as redox mediators in dye sensitized solar cells. High efficiency and current density of 2.35% and 8 mA.cm(-2), respectively, are obtained. Moreover, the electron lifetime (tau(e)) for the PAI electrolytes that contain bromide and iodide additives is calculated to be 1.38 and 0.84 ms, respectively, from electrochemical impedance spectroscopy measurements. It was observed that a high tau(e) provides favourable time to efficiently gather more electrons therefore minimizing the probability of recombination. These results illustrate the prospective of the developed PAI electrolytes to compete with other conventional electrolytes that use ionic salts.