Cocktail co-sensitization of two novel metal-free dyes and N-719: A promising strategy for enhanced performance of dye-sensitized solar cells

Abstract

The present investigation involved the synthesis and characterization of two novel metal-free dyes, MOS-1 and MOS-2, intended for use in dye-sensitized solar cells (DSSCs). MOS-1 and MOS-2 showed strong absorption in the visible region, making them suitable for co-sensitization with N719, a commonly used ruthenium-based dye in dye-sensitized solar cells (DSSCs). We compared the efficiency of DSSCs using MOS-1 and MOS-2 with N719, only MOS-1 or MOS-2, and only N-719. Co-sensitization of MOS-1, MOS-2, and N719 at the same concentration of 0.2 mM resulted in the highest efficiency of 10.45%, which was 1.4 times higher than N-719 alone. MOS-1 and MOS-2 alone also yielded impressive efficiencies of 4.75% and 5.18%, respectively. However, their efficiency was lower than N719 alone (7.27%). The enhanced efficiency of the co-sensitization system can be attributed to broader absorption and efficient electron injection, resulting in increased photocurrent and open-circuit voltage. Further information about the processes accountable for the photovoltaic enhancements was obtained through the utilization of incident photon to current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) evaluations. IPCE results showed that the increase in Jsc was due to a reduction in photocurrent loss caused by the electrolyte (I-/I3-). EIS studies indicated that electron recombination was reduced, likely due to the formation of a more compact and ordered monolayer of sensitizers resulting from increased dye absorption. Co-sensitization with metal-free dyes and N719 is a promising strategy for improving DSSC performance.