Highly efficient solution processed nanorice structured NiS counter electrode for quantum dot sensitized solar cells

Facile and nano-rice structured nickel sulfide (NiS) thin films were synthesized and utilized as counter electrode (CE) in quantum dot sensitized solar cells (QDSSCs) for polysulfide redox reactions. NiS thin films deposited on fluorine-doped tin oxide substrate results in formation of highly efficient CE for liquid-junction QDSSCs. Under illumination of 1 sun (100 mW cm−2), the QDSSC based NiS CE exhibited power conversion efficiency (η) of 2.97%, which is higher than platinum (1.45%) CE. Electrochemical impedance spectroscopy affirms that high value of η in NiS CE is due to the elevated electro-catalytic activity towards polysulfide electrolyte reduction and also due to the scale-down in the charge transfer resistance (3.16 Ω) at the CE-electrolyte interface.