New engineered and environmentally friendly dye-sensitized solar cells: Efficient extraction of dyes from Cytisus, Alcea rosea, and Roselle

In this study, an efficient extraction of natural dyes from three plants such as Cytisus, Alcea rosea, and Roselle was carried out by solid-liquid extraction method. Extraction conditions were optimized using the Response Surface Methodology (RSM). Temperature, time, and solvent ratio of extractions were the variables, and absorption intensities in maximum wavelength of extracted samples were the response of experiments. Optimum extraction conditions for the Cytisus, A rosea, and Roselle flowers were at 55 degrees C in 60 minutes, 44 degrees C in 40 minutes, and 54 degrees C in 32 minutes, respectively. Also, the best solvent for extraction of dyes was pure ethanol and pure water, respectively, for the Cytisus, A rosea, and Rosell. Moreover, results of the study showed that absorption intensities of the Cytisus, A rosea, and Roselle were equal to 1.182 at 400 nm, 1.532 at 540 nm, and 1.932 at 520 nm, respectively. To fabricate solar cells, anode electrode was coated by a thin layer of TiO2. The surface morphology of TiO2 film investigated by SEM and AFM showed a suitable homogeneity of TiO2 film without crack with an average particle size of 25 to 30 nm. Atomic force microscopy (AFM) images demonstrated that the average roughness of TiO2 thin film is about 205 nm, while the surface roughnesses of anodes was equal to 154, 101, and 119 nm after applying the Cytisus, Roselle, and A rosea on TiO2 film, respectively. Fabricated solar cells were characterized by photovoltaic and IPCE tests. Results represented that fabricated solar cells synthesized by extracted dye from Roselle had the best performance compared with other cells. The efficiency of this cell was equal to 0.842%, with an open-circuit voltage (Voc) of 0.644, a short-circuit current (Jsc) of 1.912, a fill factor (FF) of 0.683, and an incident photon-to-current efficiency (IPCE) of 18.943%.