ITO DSSC solar cells made of a transparent chlorophyll-based nanoparticle alloy (2023)

Solar cells are very expensive, so society cannot afford them. Therefore, it is necessary to consider alternative solutions for the production of photovoltaic cells in a simple, light and relatively cheap way [1]. Solar energy can be converted into electricity by using plant leaves as a DSSC dye for chlorophyll leaves [2, 3].

This research is very important because its results can make a huge contribution to low-cost and high-efficiency electricity supply, which can be used to overcome the current national energy crisis in Indonesia [4].

A solar cell is a mechanism based on the solar cell effect that absorbs photons generated by radiation and then converts them into electricity [5]. The charges in the material are due to the absorption of the material.

Currently, a very promising source of energy are dye solar cells (DSSC), which are the most advanced technology for producing energy from solar cells [6]. The main component of DSSC are leaves, which contain a large amount of chlorophyll due to photosynthesis. Solar cells using natural chlorophyll-based dyes have a higher tendency to degrade [7]. The chlorophyll content in the leaves allows more electrons to flow, creating an electric current.

Chlorophyll absorbs the energy of sunlight into molecules and releases electrons from water molecules and protons from oxygen [8]. Photosynthesis reactions are as follows:

6 $ {CO}_2+{H}_2 \mathrm{O} \frac{{sunlight}}{{chlorophyll}} {C}_6 \mathrm{H}_{12} {O}_6+6 {O} $2 (1)

Two electrons are released during photosynthesis, the more electrons are released [9]. The electrons released in photosynthesis are shown in Figure 1.

picture 1.Releasing electrons from chlorophyll leaves

Optimization of solar cell efficiency depends not only on natural dyes with high absorption or high chlorophyll content, but also on the combination, i.e. the electrical and optical properties of the transparent conductive layers used [10, 11]. In order to optimize the production of solar cells, which cannot do without the permeability of transparent conductors, energy-absorbing dyes are used [12, 13].

The electron release of the chlorophyll combined with the light transmittance level of the transparent conductive alloy and the crystallinity level of the cambium largely determine the efficiency of the solar cell. The grain size and the level of crystals formed have a great influence on the rate of diffusion of the natural dye chlorophyll.

The release of electrons in solar cells and the improvement of solar cell efficiency also greatly depends on the transparent conductors used. According to the results of research on solar cells, a good transparent conductor is a thin layer with a high reflectivity. The ITO used in the previous study had an anti-reflection index of 87.67% and a nanoparticle size of 48.71Å. The efficiency of photovoltaic efficiency obtained on papaya leaves was 0.69% [14]. With transparent conductivity as well as concentration, grain size and immersion time in TiO₂these parameters will change the pore size characteristic of the surface, which will increase the color absorption, which means an increase in light absorption [15, 16]. Therefore, pigment absorption is promising for chlorophyll phytochromes as well as absorbent materials [17]. A dye showing some progress is DSSC TiO₂[18]. To fabricate high-performance DSSCs, several components need to be optimized, including the optimization of the anti-reflection ITO, the broadening of the energy bands and the enlargement of the grains formed by TiO2₂, TiO2 concentration₂and immersion time in TiO2₂.This study will use leaves with a high content of chlorophyll, i.e. spinach leaves, cassava leaves and mango leaves, and indium tin oxide (ITO) reflective coatings and DSSC TiO2₂[19, 20].

Preliminary results of researchers [18] showed that such an approach could potentially be used in the development of DSSC photovoltaic cells. Therefore, several experimental parameters that affect solar cell performance will be optimized, namely optical properties, electrical properties, dye concentration. Of course, the concentration of the electrolyte, the annealing of all the components that make up the solar cell also affect the performance of the solar cell. Solar cells [21, 22].

In order to obtain the best DSSC solar cell, all its components are optimized in terms of optical properties, electrical properties, natural color concentration, electrolyte concentration, annealing of the manufactured DSSC solar cell.

Dye solar cells (DSSC) are a promising new generation of high-efficiency solar cells due to low-cost materials and a very simple manufacturing process. The DSSC function is due to the interaction of the TiO2 anode and cathode₂The surface is coated with a photosensitive paint and then surrounded by a sea of ​​electrolyte [21].

The results of research on the absorption of photon energy by natural colors are shown in Figure 2.

Figure 3 and Figure 4 explain the electron flow process. Photons of different energies of sunlight hit the cell and penetrate the paint layer because the tin oxide (FTO) and TiO₂Nanocrystals are transparent to visible light. During this process, holes created by photon excitation remain in the molecule because the dye is separated from all other energy levels. The holes are eventually filled with electrons from the ions of the electrolyte. At the same time, the oxidizing dye is reduced by iodide to give triiodide. The triiodide diffuses to the counter electrode and accepts electrons from the external load, regenerates the iodide, and then the whole process will ensure the flow of electrons from the working electrode to the external circuit.

photo 2.Magnified cross-section of a dye-sensitized solar cell

photo 3.DSSC mechanism of action

Figure 4.DSSC mechanism of action

The current in the DSSC was generated by injecting electrons $\left(\mathrm{S}^*\left|\mathrm{TiO}_2 \rightarrow \mathrm{S}-\right| \mathrm{TiO}_2+ \mathrm{ e } -\left(\mathrm{TiO}_2\right)\right)$ After photoexcitation of the electrons of the dye molecule by light radiation ($\mathrm{S}+\mathrm{hv} \rightarrow \mathrm {S } ^ *$). Electron capture by acceptor compounds in the electrolyte ($3 \mathrm{~S}^{-}\left|\mathrm{TiO}_2+I_3^{-} \rightarrow \mathrm{S}\right| \mathrm{TiO2 } _2+ 3 \mathrm{I}^{-}$). Recombination (electron capture) occurs between the electrons in the conduction band and the $I_3^{-}$ compound, which reduces the value of the photon current generated by the DSSC [23]. The absorption of the obtained mulberry dyeing extract is shown in Figure 5. The colored extract has the best ability to absorb red-violet light with a wavelength of 510 nm, and the absorbed light is green light.

Figure 5.Mulberry extract color absorption

Figure 6.Anton color absorption

The color absorption spectrum is shown in Fig. 5. The absorption spectrum of chlorophyll leaf extract is in the wavelength range of 190-690 nm, the maximum absorption peak of chlorophyll a is at 300 nm, and the maximum absorption peak of chlorophyll b is at 520 nm. It was observed that the dye best absorbs light with a wavelength of about 300 nm, while TiO₂Absorption is best in the range of 300 nm to 450 nm and 520 nm.

Absorption results of black glutinous rice, turmeric and hibiscus extracts at wavelengths from 200 nm to 800 nm in Figure 6. Black glutinous rice with maximum absorption at 310 nm, turmeric at 350 nm and hibiscus flower at 420 nm.

The results of efficiency tests of DSSC photovoltaic cells with papaya chlorophyll showed that the highest efficiency, i.e. 0.00071%, was achieved when the granulation of the ITO substrate was 44.46 [24].

3.1 Test scheme

Figure 7.Schematic representation of the research process

Figure 7 Research process, as above. Photosynthesis-based DSCC fabrication using transparent conductors from ITO deposition followed by TiO2 coating₂on vrhu ITO. The result is a TiO coating₂A natural leaf extract containing chlorophyll is deposited on the ITO. These results are then analyzed with XRD and UV-VIS to see the grain size and thickness of the layer formed. Then, the crystal structure and absorption were also analyzed. Based on the above analysis results, the results of the DSCC performance analysis are then analyzed.

3.2 Manufacturing process of DSSC solar panels

3.2.1 Creating a DSSC layer

(1) Production of dyes

The principle of extracting chlorophyll from papaya leaves, mango leaves and orange leaves is used to make dyes. Each sheet weighs 10 grams. Then, each leaf was washed with distilled water and dried at room temperature for 15 minutes. Then grind the pure chlorophyll leaves with a porcelain cup until smooth and place them in 50 ml of 70% alcohol solvent.

(2) Production of titanium dioxide₂pasta

in the production of titanium dioxide₂For a paste, add 2.0 g of polyvinyl alcohol (PVA) to 13.0 ml of distilled water and stir with a magnetic stirrer for about 30 minutes until the solution thickens and becomes homogeneous. PVA is used as a binder in the production of titanium dioxide₂paste. Then add 0.5 g of titanium dioxide₂Weigh the powder and add TiO2 to the resulting suspension₂Powder ratio to 5g TiO2₂Mix 15 drops or 0.75 ml of PVA with a spatula and filter through gauze.

(3) Titanium dioxide₂confused

Titanium dioxide₂layer coated on ITO glass with an area of ​​2×2 cm for TiO₂Apply a layer about 10 nm thick to the ITO surface. The sides of the ITO are taped as a barrier. TiO as previously prepared₂Put the paste on the non-sticky glass surface of the ITO, then smooth the paste on the surface of the ITO. Titanium dioxide thickness₂The applied layer corresponds to the thickness of the adhesive tape used. Titanium dioxide₂The resulting layer was left for 30 minutes, then the tape was removed and the layer was allowed to dry at room temperature to dry. For the production of titanium dioxide₂The layer is more crystalline and annealed with an electric heater lined with aluminum foil. Each color is annealed at 50°C. After cooling to room temperature, each sample with each dye was dropped onto ITO glass deposited on TiO2₂make 4 kapi make TiO₂The layer is completely covered with paint and left to dry. Then rinse with NaCl and dry.

(4) Administration of electrolytes

Add up to 4 drops or 0.25 ml of electrolyte with a pipette. The electrolyte solution is used to transfer electrons from the carbon to the dye.

3.2.2 DSSC Executive Analysis

DSSC cell testing is based on the direct light under light method. The performance and efficiency of the cell is achieved when the solar cell object is exposed to a certain intensity of light at the top electrode (anode).

The study used a constant intensity light source. The recorded DSSC output results are open circuit voltage (Voc) and short circuit current (I_SC) DSSC. DSSC output parameters include open circuit voltage (open circuit) Voc, short circuit current Isc, which can be known by measurement.

4.1 layer view

The produced samples will be analyzed using UV.Vis and XRD results for coating thickness, reflectance, absorption, grain size and coating crystallization level.

4.2 Absorption of chlorophyll dye

Chlorophyll absorption tests were performed at a wavelength of 300-800 nm using a Shimadzu UV-1601 spectrophotometer. Measure the absorbance of chlorophyll at λ using a spectrophotometer₆₄₉Nano i Lambda₆₆₅Nano. From these results, the amount of chlorophyll was calculatedA, chlorophyllB, and the total chlorophyll contained in the color by the equation,

Klorofil $\boldsymbol{a}=13,7$(OD665)-5,76(OD649)

Chlorophyll $\boldsymbol{b}=$25.8 (OD649)-7.60 (OD665)

Kupni klorofil $=20,0(\mathrm{OD} 665)+6,10(\mathrm{OD} 665)$ (2)

describe:

OD = optical density

Calculations of the adsorption of chlorophyll dye on papaya leaves (sample A), orange leaf dye (sample B) and mango leaf dye (sample C) were carried out using equation 1 (2). The results of the absorption analysis of chlorophyll dyes are presented in Table 1.

Table 1.Chlorophyll dye absorption