Co-sensitization of TiO₂-MWCNTs hybrid anode for efficient dye-sensitized solar cells

Co-sensitization of dyes on hybrid TiO₂- MWCNTs photoanode is an effective approach to enhance the performance of a dye-sensitized solar cell (DSSC). In this work, N719 sensitizer is co-sensitized with N3. The co-sensitized device showed enhanced V_OC and J_SC in comparison to single-dye sensitized devices. Upon optimization, the device made of the 0.1Mm N₃ + 0.4 mM N719 yielded J_SC = 12.5 mA cm^-2, V_oc = 0.73 V, FF = 0.45 and η = 4.1 %.This performance is superior to that of either of the individual DSSCs sensitized with N3 (3.69%) and N719 (3.51 %) under the same conditions of fabrication. The efficiency of DSSCs was further improved to 4.46% by the incorporation of MWCNTs in TiO_2. The hybrid TiO₂/MWCNTs photoanodes with different concentrations of CNTs (0.04. 0.08, 0.12, 0.16 wt. %) were prepared using mixing technique. The optimized molar ratio of N3/N719 was used for the sensitization of hybrid photonodes. Density functional theory (DFT) was used to compute the band gaps of TiO₂ and CNT-TiO₂ clusters.