DSSC

PRICKLY PEAR AS A NEW NATURAL DYE FOR DYE-SENSITIZED SOLAR CELLS WITH THIN FILMS COMPOSED OF TIO2/ZNO Mansi P. Rajyaguru, Riddhi P. Govindiya and J. H. Markna Department of Nanotechnology, V.V.P. Engineering College, Gujarat Technological University, Rajkot, Gujarat, India Abstract Today every country faces energy crises; so to overcome it, a number of solutions are given to progress towards solar energy which is rich and free to use. Dye-sensitized solar cells (DSSCs) technology comes from the concept of “artificial photosynthesis”, attempting to replicate plants ability to convert solar energy into useful energy. It represents a totally new photovoltaic technology with great potential. DSSC has been considered as the best substitute for traditional silicon-based solar cells, for their compatibility with low-cost manufacture methods and the high indoor efficiency. Natural dyeing is of great importance in the field of solar energy, thanks to its modest production and low production cost. In this research, we investigated the performance of DSSCs using a natural dye extracted from the nopal as a sensitizer for the photoanode titanium oxide/zinc oxide. Surface morphology was calculated by scanning electron microscopy (SEM) and X ray diffraction (XRD). Finally, the solar photovoltaic characterization of the solar cell was studied using the I–V characteristics. Keywords Dye-synthesized solar cell, TiO2/ZnO composite, Prickly pear Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 1. Introduction The sun is one of the green and economical energy sources. Nowadays, solar energy technology is increasingly growing worldwide and market 270 Prickly Pear as a New Natural Dye for Dye-Sensitized Solar Cells places have been established by solar cells in a wide range of tenders from shopper to modest electronics scattered energy systems. The single recent discussion on solar cell which is sensitized solar cell can considerably reduce energy desires compared with other conventional solar cells and can significantly reduce speed. The first dye-sensitized solar cells (DSSCs) were invented by Gratzel in the early 1990s. In 1991, advanced a sensitized solar cells were designed with energy conversion productivity beyond 7% and 11.4% in 2001 (Prabu et al., 2014). Associated near silicon, CdTe, and CIGS solar cells, sensitized solar cells are worthwhile, harmless, and environment friendly. From this time, sensitized solar cells can be considered as auspicious solar energy gathering expertise, which helps to control the crises of energy in the world significantly without disturbing the environment (Moradiya et al., 2018). Every hour, the sun spreads or hits the sunlight on the globe providing enough energy to gratify need of global energy for a whole year. Solar energy expertise connects the sun’s energy which makes it beneficial to mankind. A solar cell (SC) is individual of the numerous methods for conversion of solar energy into electricity. Silicon-based SCs provides quite high productivity of 15–25% for mass-produced and it is beneficial in many applications. However, the high rate and requirement for a wide space to place the solar panel are some of its disadvantages (Susanti et al., 2014). The presentation of sensitized SC rests on the selected dye and semiconductor electrode as a sensitizer. Instead the usage of standard dyes, natural dye is suitable as it is easily available, biodegradable, non-toxic, and more efficient. There are mainly three procedures that follow in DSSC. Firstly, the dye adsorbed on the titanium oxide (TiO2) layer will cooperate with sun’s light that promotes an electron to excited state level from lower energy level. After photons from the light source enter the solar cell, photoexcitation follows since the solar cell is excited by electrons in the dye. Formerly, the electron which is excited is inserted inside semiconductor (TiO2), and the chemical diffusion occurs from the TiO2 layer of electron into the fluorine-doped tin oxide (FTO) conductive film. The circuit is completed when the electron returns back to the cell (Mazalan et al., 2013). 2. Experimental section 2.1 Material The chemicals used in the research are standardized and can be easily available in the laboratory. The natural dye can be available from the environment. The FTO transparent conductive coated glass (4 mm 271 Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 Mansi P. Rajyaguru, Riddhi P. Govindiya and J. H. Markna width with side 2 × 2 cm2) was used. The chemicals used in this study were TiO2 (transparency 97%) and zinc oxide (ZnO). 2.2 Preparation of natural dye sensitizers Fresh prickly pear fruit was washed properly with distilled water to eradicate all the scums. Then it was cut into pieces and mashed using a mortar and pestle to make a liquid paste of it. Afterwards, it was added to 20 ml of ethanol. Then the remaining parts detached by purification was washed away with hexane for numerous periods to eradicate any lubricate present on the excerpt. The excerpt was directly used as a dye for sensitizing solar cell. The extracted dye in the form of liquid is shown in Figure 1 (Sakthivel and Baskaran, 2015). Figure 1. 2.3 Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 Prickly pear, fruit Preparation of photoanode TiO2 paste was primed using an analogous method defined elsewhere. Firstly (2 cm × 2 cm), FTO glasses were cleaned with ethanol and acetone for 10 min individually using an ultrasonic bath. Then a mixture of TiO2 powder (3 g) and a small amount of ZnO (0.1 ml) was taken to make a slurry of it. Check the conducting side of the glass and rub on two equivalent stripes of adhesive tape on the ends of the conductive side facing up from the glass plate used to monitor the thickness and to control the conductive part for absorption of dye. The mixture of TiO2 and ZnO prepared paste was dropped on the leftover part of the glass and was layered using “doctor blade” method (i.e., sliding a paste with a glass rod on the substrate) to cover the whole 272 Prickly Pear as a New Natural Dye for Dye-Sensitized Solar Cells plate with paste and the process of coating was carried out until it becomes homogeneous. Later, the coating on glass gets dried up at room temperature, the tape was detached cautiously without disturbing the coated layer. Then, primed coated layer was sintered at 450°C for 30 min to enrich the solidity and strength of the film. After sintering, the coated layer was allowed to dry. After the layer gets completely dry, it was allowed to immerse into the extracted dye for 1 h until the coated film is been shielded through the dye. When the dye is absorbed, the film was removed from the solution and was cleaned through distilled water as the scums present on the coated film gets removed. Lastly, the film dries up and gets ready to chain with the other electrode for the completion of sensitized solar cell device preparation. 2.4 Cell assembly To assemble the DSSC based on natural dye-sensitized TiO2 nanostructure, the prepared TiO2 nanostructure electrode which was immersed in the dye solution was placed upside down on the other counter electrode. The representation of FTO counter electrode placed over the dye-adsorbed TiO2 nanostructure electrode is shown in Figure 2 (Andargie and Worku, 2016). Then, both the glasses were clipped. (A) Figure 2. Schematic representation of solar cell Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 273 Mansi P. Rajyaguru, Riddhi P. Govindiya and J. H. Markna 2.5 Characterization and measurement Using X ray diffraction (XRD) method, the assembly of the prepared layer was studied and characterized using a Pan-Analytical XRD. For determination of the surface morphology of the prepared layer was studied with the help of characterization tool, scanning electron microscopy (SEM; VEGA 3 TE SCAN). The current–voltage (I–V) characteristics of the sensitized solar device was measured with the help of instrument white Sun 10 × 10 digital simulators (AGV Pvt. Ltd., Mumbai) which was connected with a PC. 3. Result and discussion 3.1 Structure and surface morphological examination To identify phase and orientation of the TiO2/ZnO nanocomposite, XRD method is used for the study. The pattern of TiO2/ZnO nanocomposite obtained through XRD is given away in Figure 3. The inserted figure displays the data of XRD pattern of TiO2 and ZnO in this presented research study. (A) Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 274 Prickly Pear as a New Natural Dye for Dye-Sensitized Solar Cells (B) Figure 3. The pattern of XRD image of nanostructure TiO2/ZnO. (A) XRD of ZnO and (B) XRD of TiO2 Figure 4 displays the study of surface morphology of the ZnOdoped TiO2 nanoparticles. The SEM investigation of ZnO-doped TiO2 nanoparticles revealed that the crystallites in nanometer size are homogeneous. The study demonstrates the size of grain which is spherical having a uniform shape. The dispersal of substrate is closely packed which gives rise to some minute holes. From the study of micrograph, the nature of the film is observed which result in highly mesoporous. It was also observed that the particles obtained were of constant size in aggregated clusters (Gratzel, 2017). Figure 4. SEM image of TiO2/ZnO thin film 275 Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 Mansi P. Rajyaguru, Riddhi P. Govindiya and J. H. Markna 3.2 Photocurrent–voltage (I–V) examination The photovoltaic tests of DSSCs using natural dyes were carried out using one sun illumination 0.5 cm2. The measure of current-voltage graph is shown in Figure 5. Short-circuit current (Jsc), open-circuitvoltage (Voc), fill factor (FF), and energy conversion efficiency (η) values was estimated of natural dye in sensitized solar cell. The photovoltaic characteristics of DSSCs is defined as: FF = η= J max × Vmax J sc × Voc (1) Pmax J max × Vmax FF × (Voc × J oc ) = = Pin Pin Pin (2) Here, Jmax represent maximum power point current and Vmax represent maximum power point voltage (Ganta et al., 2017). The photoelectrochemical parameters of DSSCs sensitized with the extract of prickly pear were shown in Figure 5 and Table I. From Figure 5, values of short-circuit current (Jsc), open-circuit voltage (Voc), FF, and energy conversion efficiency (η) of DSSCs with the (TiO2/ZnO) are 0.30 mA.cm−2, 0.48 V, 0.65, and 0.08, respectively. And when (TiO2/ZnO + extracted dye) is used, the values are 0.85 mA.cm−2, 0.55 V, 0.58, and 0.24, respectively. These results show that high Jsc values are obtained when natural dye extracted from prickly pear is added to the TiO2/ZnO paste (Selvaraj et al, 2018). (A) Proceedings of SSIP Annual Conference on Student Innovation, Start-ups and Ecosystem – 2019 (B) Figure 5. Current–voltage curve of DSSC: (A) TiO2/ZnO and prickly pear dye and (B) TiO2/ZnO paste 276 Prickly Pear as a New Natural Dye for Dye-Sensitized Solar Cells Table I. Photoelectrochemical parameters TiO2/ZnO Prickly pear Voc (v) Jsc (mA cm−2) Fill factor (FF) Conversion efficiency (η) 0.48 0.55 0.30 0.85 0.65 0.58 0.08 0.24 4. Conclusion In summary, a dye obtained from nature which grows with nominal H2O and light was preferred as best sensitizers in sensitized solar cell. The natural DSSC was prepared with extracted prickly pear as a dye. Additionally, a composite layer was prepared of TiO2/ZnO on conducting substrate using doctor blade method to gain the preferred conductive range. The surface morphology of TiO2/ZnO thin film was calculated by SEM. XRD examination for structural properties was also carried out for TiO2 and ZnO. The I–V measurements of the made sensitized solar cell using prickly pear as sensitizers got the remarkable values of short current (Jsc), open circuit voltage (Voc), FF, and conversion efficiency (η) as 0.85, 0.55, 0.58, and 0.24, respectively. Overall, the naturally extracted dyes used as sensitizers are auspicious due to their low fabrication rate, modest, and ecological kindliness. Acknowledgment J.H. Markna stays grateful towards GUJCOST (DST – Gujarat Government), Gandhinagar on behalf of their commercial funding (GUJCOST/MRP/2015-16/2607). References Andargie, W. and Worku, D. 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