Thiocyanate-free isoquinazolylpyrazolate Ru(II) complexes were synthesized and applied as sensitizers in dye-sensitized solar cells (DSCs). Unlike most other successful Ru sensitizers, Co-based electrolytes were used, and resulting record efficiency of 9.53% was obtained under simulated sunlight with an intensity of 100 mW cm-2. Specifically, dye 51-57dht.1 and an electrolyte based on Co(phen)3 led to measurement of a JSC of 13.89 mA cm-2, VOC of 900 mV, and FF of 0.762 to yield 9.53% efficiency. The improved device performances were achieved by the inclusion of 2-hexylthiophene units onto ...