Synergistic effect of complementary organic dye co-sensitizers for potential panchromatic light-harvesting of dye-sensitized solar cells

Dye co-sensitization technique is a promising strategy adopted to establish a broader absorption wavelength and higher spectral response towards panchromatic light-harvesting of dye-sensitized solar cells, DSSC. In this work, the co-sensitizing between chlorophyll pigment extracted from Mitragyna Speciosa (kratom) and anthocyanin pigment extracted from Rubus Fruticosus (blackberry) has been successfully investigated. Five different volu-metric ratios of chlorophyll and anthocyanin dyes were analyzed through ultraviolet-visible spectroscopy, UV-Vis, Fourier-transform infrared spectroscopy measurements. FTIR, current to voltage characteristics, I-V and incidence photon to current efficiency, IPCE measurement. It was discovered that the optimal volumetric ratio of Anth-80%, Chll-20% (Co-B) has contributed to a remarkably higher power conversion efficiency, PCE, due to its constructive complementarity and interconnected absorption peaks, broadening its light spectral response throughout the visible region. Furthermore, the lower bandgap energy difference, oEg, between the two sen-sitizers promotes parallel spectral response in the 500-700 nm range. As a result, a significant increase in the IPCE spectra of the co-sensitized system up to 900 nm indicates panchromatic light sensitization properties. The substantial increase in the IPCE spectra has contributed to the rise in the Co-B cell's photocurrent density, JSC. Finally, the availability of various functional groups responsible for attaching the dye to the TiO2 semiconductor surface increased the dye adsorption and coverage, resulting in the formation of an effective organic passivation layer that prevents back carrier recombination. At their most optimal volumetric ratio, these combined effects have boosted the Co-B cell's efficiency to 0.37%.