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

Abstract

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 cm², V_oc = 888 mV, FF = 57.44, and η = 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⁻/I₃⁻, dye aggregation, and charge recombination.