Strategic design and synthesis of novel tridentate bipyridine pyrazolate coupled Ru(II) complexes to achieve superior solar conversion efficiency

A new series of tridentate bipyridine pyrazolate coupled Ru(ii) complexes CK1, CK2, HY1 and HY2 were strategically designed and synthesized. In comparison to N719, CK2 and HY2 achieved the original proposal of obtaining an absorption extinction coefficient ranging from 350 to ∼550 nm, accompanied by lowering of the lowest lying energy gap. These advantages allow us to reduce the thickness of the TiO₂ layer, resulting in great suppression of the dark current and hence an increase of V_oc. Upon optimization, HY2 attained η = 8.07, J_sc = 15.81 mA cm^-2, V_oc = 753 mV and FF = 0.678, the results of which are equivalent to that of N719 (η = 8.02, J_sc = 15.70 mA cm^-2, V_oc = 765 mV and FF = 0.668) maximized in this study.