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

Abstract

<p style="text-align: left;">In this study, an efficient extraction of natural dyes from three plants such as Cytisus,&nbsp;<i>Alcea rosea</i>, 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,&nbsp;<i>A&nbsp;rosea</i>, and Roselle flowers were at 55&deg;C in 60&nbsp;minutes, 44&deg;C in 40&nbsp;minutes, and 54&deg;C in 32&nbsp;minutes, respectively. Also, the best solvent for extraction of dyes was pure ethanol and pure water, respectively, for the Cytisus,&nbsp;<i>A&nbsp;rosea</i>, and Rosell. Moreover, results of the study showed that absorption intensities of the Cytisus,&nbsp;<i>A&nbsp;rosea</i>, and Roselle were equal to 1.182 at 400&nbsp;nm, 1.532 at 540&nbsp;nm, and 1.932 at 520&nbsp;nm, respectively. To fabricate solar cells, anode electrode was coated by a thin layer of TiO₂. The surface morphology of TiO₂&nbsp;film investigated by SEM and AFM showed a suitable homogeneity of TiO₂&nbsp;film without crack with an average particle size of 25 to 30&nbsp;nm. Atomic force microscopy (AFM) images demonstrated that the average roughness of TiO₂&nbsp;thin film is about 205&nbsp;nm, while the surface roughnesses of anodes was equal to 154, 101, and 119&nbsp;nm after applying the Cytisus, Roselle, and&nbsp;<i>A&nbsp;rosea</i>&nbsp;on TiO₂&nbsp;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%.</p>