The potential of mixed dyes of Morus nigra L. and Sargassum binderi as photo absorber layer in solar cell devices

The application of natural plant-derived dyes as photo-absorber in solar cells application, have been extensively studied and proven. Natural plant-derived dyes are known containing natural compounds (e.g. carotenoids, chlorophyll, anthocyanin) that have the characteristics of electronic delocalization in extended πorbital system involving in electronic transfer mechanism. Hence, the mixture of Morus nigra L. (mulberry, M) and Sargassum binderi (seaweed, S) were successfully prepared and several physical characterizations were carried out such as UV-vis, TGA and SEM to analyse the photo-absorber (sensitizer) properties. From the results obtained, by adjusting the ratios of M:S into 1:10, 3:1, 30:1, the wavelength of photo-absorbers were slightly changed. TGA result showed that S has higher melting point than M. Meanwhile for SEM results, the M dye particles on titanium dioxide (TiO2) were in porous structure with smooth surface and the existence of both distinct shapes of both individual dye (M and S). The highest conductivity was recorded by 30M:1S with the value 0.629 V followed by the 3M:1S with the value of 0.563 at the distance of 15 cm from source of light . The result pattern was found similar trend to the previous analysis by four point probe, which mixed dyes can conduct more electricity compare to single dye. From the results, it show that mixed dye performed higher solar efficiency compared to the individual dye (M and S), as example, the mixed ratio of 30 M:1 S formed 9.44x1002 % of solar efficiency with M and S only 9.2x10-02 % and 3.68x10-02 % respectively. Overall results suggesting that by adjusting the ratio mixture of mixed dyes solution, the photo-absorber properties and the solar efficiency values were differed and with slight modification method, better electrical conductivity can be expected for solar cells application.