DOE OSTI2022
Copper redox shuttles, particularly [Cu(tmby) 2 ] 2+/1+ (tmby = bis(4,4',6,6'-tetramethyl-2,2'-bipyridine)), proved to be among the best electrolytes for dye-sensitized solar cells (DSCs), realizing higher power conversion efficiencies both under full sun and indoor illumination than conventional iodide/triiodide and cobalt electrolytes. Even though [Cu(tmby) 2 ] 2+/1+ renders a relatively higher performance, this metal complex is bulky and is limited by mass transport. Since the regeneration of the dye ground state by Cu I and the reaction of Cu II at the counter electrode are comparatively faster processes, the efficiency of DSC involving Cu I /Cu II electrolytes under relatively high light intensities is largely governed by the diffusion of Cu I /Cu II species. Understanding mass transport in these solar cells will enable further improvements in the performance of such copper-based DSCs. Here in the present study, the role of illumination intensity on the photogenerated current and its relationship to mass transport is evaluated using the best cosensitized dye (D35:XY1) and copper electrolyte ([Cu(tmby) 2 ] 2+/1+ ) combination.