Morphology controllable time-dependent CoSnanoparticle thin films as efficient counterelectrodeforquantumdot-sensitizedsolarcells

Highlights: • CoS thin film is deposited on FTO glass by a facile chemical bath deposition method. • The surface of the CoS films exhibit uniform nanoparticle morphology. • Morphology and electrocatalytic activity of CoS CE are varied with deposition time. • The power conversion efficiency of 3.67% with CoS 3 h CE based QDSSCs. Cobalt sulfide (CoS) agglomerated nanoparticle thin films obtained by a facile chemical bath method at different deposition times. The CoS counter electrode (CE) deposited at 3 h deposition time (CC-3h) based quantum dot sensitized solar cells (QDSSCs) achieves higher power conversion efficiency (η) of 3.67% than those of CC-2h (1.83%), CC-4h (2.52%), and Pt (1.48%) CEs, under one sun illumination (100 mW cm⁻², AM 1.5 G). The electrochemical analysis revealed that CC-3h CE shows a smaller charge transfer resistance (9.22 Ω) at the CE/electrolyte interface than the CC-2h (23.34 Ω), CC-4h (19.73 Ω) and Pt (139.92 Ω) CEs, respectively.