Enhanced photovoltaic performance with co-sensitization of a ruthenium(II) sensitizer and an organic dye in dye-sensitized solar cells

Co-sensitization is demonstrated to be an effective technique to enhance the efficiency of dye-sensitized solar cells, where an efficiency of 9.23% is achieved by mixing N3 and RK-1 dyes. The assembled solar cells are characterized by UV-vis absorption measurements, current-voltage characteristics, and electrochemical impedance spectroscopy. The co-sensitized solar cell shows an enhanced photovoltaic performance as compared to the devices sensitized by individual dyes. Upon optimization, the device made of 0.3 mM N3 + 0.2 mM RK-1 yielded J(sc) = 18.1 mA cm(2), V-oc = 888 mV, FF = 57.44, and eta = 9.23%. This performance is superior to that of solar cells sensitized with either N3 (6.10%) or RK-1 (5.82%) fabricated under the same conditions. The enhanced efficiency can be attributed to the decrease of the competitive light absorption by I-/I-3(-), dye aggregation, and charge recombination.