Dye Oriza sativa glutinosa doped Fe as a active element of Dye Sensitized Solar Cell (DSSC)

The aims of the research are to determine the effect of doping Fe (III) Sulphate into dye Oriza sativa glutinosa on the characteristics parameters of solar cells, to determine the optical characteristic, functional group and electrical characteristic of dye Oriza sativa glutinosa doped Fe (III) sulphate. TiO2 nano size as much as 0.5 gr dissolved in 3 ml ethanol. 100 gr black sticky rice (Oriza sativa glutinosa) was immersed in 80 ml ethanol solution (95%) and kept at room temperature without exposing to light. Then it was filtered with a filter paper no.42, and the extracted result was process with chromatography. Furthermore, it was doped with Fe (III) sulphate respectively of 10-1 M, 10-2 M, 10-3 M. The characteristic of dye solution was measured using UV-Visible Spectrophotometer Lambda 25 for absorbance, Elkahfi 100/I-V meter for conductivity amd Keithey 2602A for characterization of current and voltage (I-V). The result showed that the area of dye Oriza sativa glutionosa doped Fe (III) sulphate with concentration 10-1 M the largest, because the value of Voc intercept at 6.40 × 10-1 mV and the value Isc intercept at 1.89 × 10-3 mA, with efficiency value is 0.148%.


Introduction
Dye sensitized solar cells (DSSC) is one type of solar cells which is attractive to be studied and development as an alternative way to substitute the conventional solar cells based on silicon semiconductor over the last decade. There are some advantages of DSSC, easy to fabricate, low cost and environmental friendly [1]. A DSSC is composed of a nanocrystalline porous semiconductor electrode-absorbed dye, a counter electrode, and an electrolyte containing iodine and triiodide ions. [2]. The principle of operation of DSSC is based on sensitization of a wide band-gap metal oxide semiconductor to the visible light region by an adsorbed molecular dye. When the metal oxide semiconductor film is immersed in the dye, a monolayer of the dye is anchored onto its surface. Excitation of atoms by sun light occurs in the dye and the photogenerated charges are separated at the interface between the dye and metal oxide [3]. The DSSC sensitized by Ru-containing compounds are reaching, 11-12% the highest efficiency as reported by Chiba and Islam [1]. However, noble metals limited in amount, and costly in production. Therefore, alternative organic dyes such as natural dyes have been studied intensively. Although its absorbance ability is lower than dye synthetic, such as ruthenium complex, but the findings of Hao et al. [4] and Yuliarto et al. [5] showed that extracts of black rice can be used as photosensitizer in DSSC. Furthermore, Hao et al. [4] also report that the dye of black rice extract is the best natural dye be caused, this kind of dye can absorb wavelength in wide spectrum. The anthocyanin pigments contained in black rice was over 80% of cyaniding-3-glucoside, the other minor pigments were peonidin-3-glucoside, malvidin-3-glucoside, and cyanidin-3ramnoglucoside [6]. Saehana et al. [7] reported that a conversion efficiency of 0.17% was obtained using black rice dye as sensitizer. Until now, variations of the optimization is done by many researchers to improve the efficiency and stability of performance dye sensitized solar cell. Therefore, various engineering has been carried out such as by modifying the TiO 2 electrode, electrolyte and, dye used [8]. This research studied the effect of doping Fe (III) Sulphate into dye Oryza sativa glutinosa as photosensitizer for dye sensitized solar cells. Selection of iron complex is based on ferrous metals located in the transition metals in which the electron configuration d 6 as ruthenium and Osmium (used as dye solar cells), have quantum relatively high to produce sensitization of nanocrystalline TiO 2 , soluble in polar solvents, and its wavelength at visible region is 551 nm.

Preparation of TiO 2 Solution
TiO 2 nano powders as much as 0.5 gr dissolved in 3 ml of ethanol, then stirred using a vortex stirrer with a speed of 300 rpm for 30 minutes. TiO 2 paste was stored in closed container lined with aluminium foil.

Preparation of Electrolyte
Natrium iodid (NaI) of 2 grams are mixed into 3.68 ml acetonitrile added 1 ml propylene carbonate.
Further to the solution is added 14.56 ml polyethylene glycol then stirred. Further to the solution is added iodine (I 2 ) of 0.2 grams was stirred with a vortex stirrer at 300 rpm for 30 minutes. Electrolytes solution was stored in closed containers lined with aluminum foil.

Preparation of Counter Electrode
To prepare platinum catalyst coated on FTO glass substrate, 1 ml hexachloroplatinic acid solution in 207 ml isopropanol was spread on the FTO conducting surface. The Pt-coated FTO counter electrode was then heated in a furnace at 250 0 C for 15 minutes.

Preparation of the TiO 2 /Dye Electrode
The FTO glass (1 × 1 cm 2 ) was cleaned with distilled water and ethanol to remove impurities. The cleaned FTO surface was coated with TiO 2 paste using spin coating techniques. The FTO/TiO 2 electrodes were sintered at 450 o C for 30 minutes. The electrode were immersed in the dye solution for 24 hours. The white TiO 2 film will change color when dye is absorbed.

Fabrication of Natural Colorant-Sensitized Solar Cells (DSSC)
Natural colorant-sensitized solar cells with active area about 1 cm 2 were fabricated by sandwiching the electrolyte between TiO 2 /dye electrode and Pt counter electrode. The I-V characteristics of DSSC were obtained under light illumination (1000 W/m 2 ) using keithley 2602A source meter.

Absorption Spectra of Black Sticky Rice doped Fe (III) Sulphate
Before being used as a sensitizer, extract black sticky rice and extract black sticky rice doped Fe (III)  Absorbance dye of the fourth materials showed that the value of wavelength of these material are able to work on the UV-Visible light. From Figure 1, doping Fe (III) sulphate into the dye causes peak absorbance by dye shifted from wavelength 553 nm becomes 595 nm, 601 nm, and 660 nm. In this case there has been a process of intermolecular copigmentation between anthocyanin extract of black sticky rice with copigmen compound of Fe (III) sulphate which is characterized by a bathochromic shift. Bathochromic shift causes absorption peak shifts towards larger wavelengths. .81 cm -1 showed the C-H bonds (alkanes) in an area stretching hydrogen, the intensity of absorption that form C-H bonds (alkanes) to be reduced due to vibration in the catchment area occurs with changes in dipole moment that is smaller because no polar OH covalent bonds with Fe (III). In spectra 1745.65 cm -1 showed the C=O stretching in the double bond with a very high intensity of absorption. Therefore carbonyl group in black sticky rice extract is very polar, so this stretching bond is produced change dipole moment is quite large. Then the intensity of absorption form C=O stretching bond is reduced because doping Fe (III) sulphate into extract of black sticky rice change molecular structure of the carbonyl group in ketones which causes the frequency of C=O stretching vibration become lower.  Based on the graph in Figure 4, it can be shown that the dye extract black sticky rice doped Fe 10 -1 M has the largest area, because the value of V oc intercept at 6.40 × 10 -1 mV and the value I sc intercept at 1.89 × 10 -3 mA. Therefore, it has the largest value of efficiency. In generally, the results of the efficiency of the extract black sticky rice without Fe (III) sulphate and black sticky rice doped Fe (III) sulphate with concentrations 10 -1 M, 10 -2 M, 10 -3 M, are shown in Table 1. small (under 1%). There are two kind of efforts to increase the performance DSSC. The first, using different counter electrode with polyaniline (PANI), because PANI can increase efficiency from 6.90% using platinum to 7.15% using PANI [10]. The second, using the kind of electrolyte which has viscosity is smaller than PEG electrolyte such as PEO polymer gel [11].

Summary
From the results of this study concluded that the solar cell DSSC has been successfully created by using dye extract black sticky rice and extract black sticky rice doped Fe with various concentrations. The results of the absorbance dye showed that the value of wavelength these material are able to work on the UV-Visible light. The largest conductivity value is dye extract black sticky rice doping Fe (III) sulphate with concentration 10 -1 M, whereas the greatest efficiency in achieved by using the extract black sticky rice doped Fe (III) sulphate with concentration 10 -1 M on 24 hour immersion in the amount of 0.148%.