Hierarchical micro/nano-structured titanium nitride spheres as a high-performance counter electrode for a dye-sensitized solar cell

Abstract

Hierarchical micro/nano-structured TiN spheres (micro/nano-TiNs) counter electrodes are fabricated by coating hierarchical micro/nano-TiO2 paste onto Ti foil followed by a nitridation reaction. Compared with particulate TiN and TiN flat electrodes, the as-prepared hierarchical micro/nano-TiNs electrode based dye-sensitized solar cells (DSCs) delivers significantly improved photovoltaic performances due to the presence of the hierarchical structure. In particular, VOC is enhanced by about 60 mV, which may be predominantly attributed to the gaining of favourable interfacial active sites and the traces of N-doped carbon residues. After an initial optimization of the particle sizes of the hierarchical micro/nano-TiNs, the reflectance effect of large submicroscale particles is attempted to improve the ISC. The highest overall conversion efficiency yields 7.83%, which is 30% higher than that of Pt/FTO (6.04%).