ABSTRACT: The development of new types of solar cells is promoted by increasing public awareness that the earth’s oil reserves could run out during this century. As the energy need of the planet is likely to double within the next 50 years and frightening climatic consequences of the greenhouse effect caused by fossil fuel combustion are anticipated, it is urgent that we develop a new kind of renewable energy to cover the substantial deficit left by fossil fuels. Since the prototype of a Dye Sensitized Solar Cell (DSSC) was reported in 1991, it has aroused intense interest owing to its low cost, simple preparation procedure, and benign effect on the environments. However, the potential problems caused by liquid electrolyte limit the long-term performance and practical use of DSSC. Therefore, much attention has been given to improving the light-to-electrical power conversion and replacing the liquid electrolytes by solid-state or quasi-solid- state electrolytes. This review will focus on progress in the development of improved electrolytes, especially quasi- solid-state electrolytes such as Titanium Dioxide (TiO 2 ) for DSSC’s.
The world’s energy focus has shifted from burning fossil fuels to relatively less expensive, efficient and renewable resources especially the solar energy as indicated in . This is due to the fact that fossil fuel is slowly, but inevitably vanishing and produces gases that have a negative effect on environment, health and climate as stated in [2, 3] . In addition, the worldwide energy consumption is expected to double in the next four decades due to rapid population increase and technological dynamism in many developing countries as stated by Hamann et al . The authors in  states that as a consequence of dwindling fossil fuel resources, a huge power supply gap of 14 terawatts is expected by 2050. According to Gratzel  solar energy, being abundant, is expected to play a crucial role as a future energy source. In an attempt to utilize the energy from the sun, scientists have deployed photovoltaics, a field of technology and research related to the devices which directly convert photons of light of specific wavelengths into electricity. The solar cell is the elementary building block of the photovoltaic technology. The solar cell is made of semiconductor materials and they include wafer-based silicon solar cells, amorphous thin film, Cadmium Telluride and dye sensitized solar cell with silicon being the main area of focus. Silicon solar cells have some shortcomings with its biggest problem being cost since they require a relatively thick layer of doped silicon in order to have reasonable photon capture rates, and silicon processing is expensive as explained by Chung et al. . There have been a number of different approaches to reduce this cost over the last decade, notably the thin-film approaches, but to date they have seen limited application due to a variety of practical problems. Another line of research has been to improve efficiency through the multi-junction approach, although these cells are expensive and suitable only for large commercial deployments. Energy conversion efficiency of a crystalline silicon-based solar cell is 24.4%, which is more than twice DSSC’s which is closer to 11%.
Oprea  has studied the maximum absorption spectrum of the deprotonated dyes and neutral dyes, UV/Vis absorption peak of all coumarin dyes shown good results, it also matches with experimental data (NKX-2311 has maximum light harvesting property) and the electron has the tendency to localized near to the COO- group by absorbing the photons. The ma x i mu m a b s o r b ance of the berry solution is 440 nm. This decrease in transmittance, in turn, enhances the absorption of the films, thereby increasing the photon efficiency. UV-Visible absorption spectra are very intense and wide absorption band regions, dye molecule with maximum absorption wavelength at 660 nm the higher excitation is due to π→π* transition, whereas sharp peaks at 440 nm indicates n→π* transition, pelargonidin dye molecules has double excitation at near 440 nm and 528 nm are shown in Figure 4. The molar attenuation coefficient of all dyes has increased due to the presence of hydroxyl groups in B ring position of dyes. And also due to the presence of –OH (hydroxyl group) the absorption is shifted to near UV spectra with maximum extinction coefficient. The absorption bands of both graphs show that the transition to high absorption intensity and excitation energy. The efficient dye sensitizer used for DSSC should have high Light Harvesting Efficiency (LHE), which can be expressed by following equation :
Abstract— Dye Sensitized Solar Cells (DSSCs) are the thin film low cost solar cells. It is based on the semiconductor formed between photo sensitized anode and electrolyte. It is a photo electrochemical system. DSSC are simple to make, flexible and transparent. The price to performance ratio is good. DSSC Consist of Transparent Conductive oxide (TCO) glass, Dye sensitized Nanoparticle, electrolyte and counter-electrode. Conversion efficiency depends on type of electrolyte used, materials which curbs recombination, type of dye and Nanoparticles. This study brings various possible arrangements of TCO and organic and natural dye sensitization of Nanoparticles and various electrolyte used in DSSC. By modifying a various component the conversion efficiency of the DSSC are increased. This study focuses on various strategies followed to increase conversion efficiency.
PEDOT:PSS/glass CE has obtained higher FF of 0.51 and thus higher η = 4.67% (increasing 22% compared with 3.64% for the DSSC with PEDOT:PSS/FTO CE). This is mainly due to the reduced charge transfer resistance and porous diffusion impedance because of the large electro- chemical surface area in the porous TiO 2 -PEDOT:PSS
We modified the PEDOT:PSS (Poly ethylene dioxy thiophene: Poly styrene sulphonate) counter electrode in four different ways using MWCNTs and a sandwiched type cell is made with Lawsone a natural dye and Iodine as electrolyte. Electrical characteristics are plotted and photovoltaic parameters are measured for three consecutive days. It is found that DSSC with fMWCNTs in PEDOT:PSS as counter electrode shows maximum J sc (2.63mA/cm 2 ) and efficiency (0.6%).
coating, photocatalysts and so on [1-6]. Hesperidin shows a characteristic flavanone absorption spectrum with UV maxima at 286 and an inflection of low intensity at 330 nm. Hesperidin appear to be extremely safe and without side effects. Hesperidin has nontoxic both to the human beings and to nature, easily assimilated, non accumulative and caused no allergic reactions. Hesperidin is an abundant and inexpensive by-product of Citrus cultivation and is the major flavonoid in sweet orange and lemon. In paper work is focusing in the direction of systematic sample preparation, characterization, and find out optical parameters from physical phenomena such as absorption, transmission, reflection, and also application of solar cells in the form of DSSC for using Hesperidin pigment [8, 9].
the notable difficulties stimulated the researchers and industrialists to develop alternate sensitizers, particularly organic dyes. Next to ruthenium complex, organic dyes based DSSC offers maximum efficiency of up to 9% and it shows highest absorption coefficient . Most of the literature supports that the organic dyes employed in DSSC can as well be replaced with the dyes extracted from natural products like flowers, fruits, vegetables, leaves etc. It is highly desirable to explore this type of non toxic natural dye with good optical properties to the research. Easy availability, eco friendly, easy fabrication, low extraction temperature and cost of purification are the important advantages of the natural dyes over other type of sensitizers. Most of the natural products show various colors and this may be attributed to the various pigments such as anthocyanins, carotenoids, and chlorophyll present in it. Generally, the increase in the ratio between the rate of forward (charge injection) and reverse (recombination) reaction process is the key tool to optimize the sensitizer . Enough energy levels for efficient electron transport and more anchoring groups to bind semiconductors are the two important features that sensitizer should meet . Orttiz et al.  achieved the efficiency of 0.19% for annatto dye sensitized ZnOnanoparticles and 0.01% for bixin sensitized ZnO cells. Wongcharee et al.  fabricatedsolar cells using natural dyes extracted from rosella, blue pea and a mixture of the extracts and has reported the efficiency to lie in the range of 0.57– 0.33%. Thambidurai etal  observed the solar cell efficiency as 0.33%, 0.41% and 0.28% for ixoracoccinea, mulberry and beetroot dye based ZnO solar cells.
Dyes extracted from Bixa Orellana .L seedhave resulted in the DSSCs with highest efficiency. This is expected because of the presence of deeper and darker coloration of the seeds extracts due to the presence of anthocyanins which have an increased absorption of light in visible spectra as depicted in „‟fig.5‟‟. The result leads us to believe that darker dyes are preferable candidates due to their increased absorption of visible light as compared to lighter ones(as observed in Plumeriarubra. L flower) leading to an increased photo current densities.Moreover, in this study it is found that extracting solvent has a crucial rule in the response of the cells.The DSSC sensitized with dye extracted with ethanol is found to have the best efficiency.
Abstract— The natural dye, Curcumin, was extracted from Curcuma longa using as a sensitizer in two types of dye sensitized solar cell (DSSC), and their characteristics were studied. The absorption spectrum of the dye solutions, as well as the wavelength of the maximum absorbance of the dye loaded TiO 2 film has been studied. The X-Ray diffraction
¡-terpineol. The overall thickness of the indium tin oxide (ITO) glass (12 ³/square, Solaronix, Switzerland) used for the electrode was 1.1 mm. It was coated with a ﬁlm of ITO, 150 to 200 nm thick. The photosensitive dye N-719 (rutheni- um 535 bis-TBA, Solaronix, Switzerland) was dissolved in acetonitrile (Samchun Chemical Industries, Ltd., Korea) and tert-butyl alcohol (extra pure, Dae-jung Chemicals & Metals Co., Ltd., Korea). Iodolyte AN-50 (iodide-based redox electrolyte, Solaronix, Switzerland) was used for the electro- lyte. Sealing sheet (Surlyn SX 1170-60, DuPont, USA) was used to assemble the two electrodes.
Dye sensitized solar cells attract much attention for a clean energy generation device. Among several solvents for the electrolyte, we investigated here the cell characteristics with acetylacetone as a solvent. The electric conductivity of the electrolyte increases as the concentration of polyethylene glycol (PEG) de- creases or that of ionic liquid increases. The addition of pyridine into the electrolyte improves both the open voltage and the short current density. On the other hand, the replacement of PEG with fluorinated oligomer in the gel electrolyte highly increases the short current density where the open voltage is not varied. As the concentration of ionic liquid increase, the open voltage and the short current density gradually increase. When more than 20 wt.% of the ionic liquid was mixed, the gelation was not obtained. As a result, acetylace- tone is a practical solvent for a gel electrolyte with the fluorinated oligomer and ionic liquid.
Film thickness and refractive index of TCO layer are very important factors on solar cell efficiency. Film thickness depends on the deposition time and the distance between spray gun nozzle and the glass substrate. The velocity and the feed-rate of the solution should be carefully controlled by the control button of the spray gun. In this work, spray pyrolysis technique is the simplest method for the deposition of SnO 2 :F thin film. Film
Abstract: Gum Arabic based Dye Sensitized Solar Cells (DSSC) with five types of dyes (Coumarin 500, Ecrchrom Black, Rhodamin B, DDTTc and Nile blue) were fabricated on ITO glass. Microstructure and cell performance of the solar cells with (ITO/ Gum Arabic / dye /ITO+ graphite and Iodine) structures were investigated. Photovoltaic devices based on the Gum Arabic / dye hetrojunction structures provided photovoltaic properties under illumination. Absorption and energy gap measurement of the (Coumarin 500, Ecrchrom Black, Rhodamin B, DDTTc and Nile blue) were studied by using UV-VS mini 1240 spectrophotometer and light current-voltage characteristics. The five (ITO/ Gum Arabic / dye /ITO+ graphite) solar cells were produced and characterized, which provided efficiency (η) and Energy gap 4.92 % for Eg = 1.436 eV ,1.9 % for Eg = eV ,2.01, 0.44 % for Eg = 2.641 eV and 0.37 % for Eg = 4.197 respectively. It is very interesting to note that the efficiency increases as the energy gap decreases. However for Ecrchrom Black the efficiency is high which may be related to high transparency that allows more photons to liberate electrons from gum layer. E
revealed by a scanning electron microscope (SEM, Philips XL-30ESM, Holland) equipped with an energy dispersive X-ray detector (EDX, EDAX Genenis-4000, USA). UV-Vis DRS and UV-Vis absorption spectra were recorded by a Shimadzu 1800 spectrometer. Photovoltaic measurements employed an AM 1.5 solar simulator. The power of the simulated light was calibrated to be 100 mWcm -2 by using a reference Si photodiode equipped with an IR-cutoff filter (KG-3, Schott), which was calibrated at three solar-energy institutes (ISE (Germany), NREL (USA), SRI (Switzerland)). I-V curves were obtained by applying an external bias to the cell and measuring the generated photocurrent with a Keithley model 2400 digital source meter. The voltage step and delay time of photocurrent were 10MV and 40 ms, respectively. Based on I–V curve, the fill factor (FF) is defined as:
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At last, the photoanode side (where the incident light comes in) of the DSSC device was spin coated of Polydimethylsiloxane (PDMS) at 300 rpm for 15 sec and then 500 rpm for 20 sec. The PDMS solution was made by dissolving PDMS particle into DI water (weight ration of 1:10) with strong agitation. Then the PDMS solution was statically stored in vacuum chamber for one hour so that the tiny bubbles generated during stirring can eliminated. After spin coating of the PDMS film the subwavelength moth-eye structured PMMA film then attached onto the PDMS layer. The process should be very careful so that no air bubble was left at the interface. The device then dried at room temperature for 12 h. Figure 1 shows the structure of additional moth-eye subwavelength AR layer DSSC device that we have designed and fabricated in this study.
In a traditional solid-state semiconductor, a solar cell is made from two doped crystals, one doped with n-type impurities (n-type semiconductor), which add additional free conduction band electrons, and the other doped with p-type impurities (p-type semiconductor), which add additional electron holes. When placed in contact, some of the electrons in the n-type portion flow into the p-type to "fill in" the missing electrons, also known as electron holes. Eventually enough electrons will flow across the boundary to equalize the Fermi levels of the two materials. The result is a region at the interface, the p-n junction, where charge carriers are depleted and/or accumulated on each side of the interface. In silicon, this transfer of electrons produces a potential barrier of about 0.6 to 0.7 Volt. When placed in the sun, photons of the sunlight can excite electrons on the p-type side of the semiconductor, a process known as photoexcitation. In silicon, sunlight can provide enough energy to push an electron out of the lower-energy valence band into the higher-energy conduction band. As the name implies, electrons in the conduction band are free to move about the silicon. When a load is placed across the cell as a whole, these electrons will flow out of the p-type side into the n-type side, lose energy while moving through the external circuit, and then flow back into the p-type material where they can once again re-combine with the valence-band hole they left behind. In this way, sunlight creates an electric current. In any semiconductor, the band gap means that only photons with that amount of energy, or more, will contribute to producing a current. In the case of silicon, the majority of visible light from red to violet has sufficient energy to make this happen. Unfortunately higher energy photons, those at the blue and violet end of the spectrum, have more than enough energy to cross the band gap; although some of this extra energy is transferred into the electrons, the majority of it is wasted as heat. Another issue is that in order to have a reasonable chance of capturing a photon, the n-type layer has to be fairly thick. This also increases the chance that a freshly ejected electron will meet up with a previously created hole in the material before reaching the p-n junction. These effects produce an upper limit on the efficiency of silicon solar cells, currently around 12 to 15% for common modules and up to 25% for the best laboratory cells (About 30% is the theoretical maximum efficiency for single band gap solar cells
Abstract- The dye sensitizer plays an important role of absorption photons in the ultra-violet, visible and infrared regions of solar spectrum. So, the dye sensitizer has to be broad absorption band, non-toxicity, stability and good matching of HOMO/LUMO levels of the dye with the bottom edge of conduction band of semiconductor and the redox potential of electrolyte. It is necessary to make the good chemical bonding between the semiconductor and the dye for effective electron transfer. In this work, the optical properties of natural dyes extracted from the leaves of Henna, Teak and Burmese iron-wood have been studied by UV-VIS spectroscopy to improve the efficiency of dye-sensitized solar cell. The band-gap energies of dye solutions are about 1.8 eV. According to the light harvesting efficiencies of different natural dyes, Henna and Teak strongly absorb the high-energy photons in UV region, and they can also absorb the photons in the visible region up to 700 nm. Furthermore, Teak has the broader absorption range and can absorb the photons in NIR region. But Burmese Ironwood dye cannot absorb high energy photons in the UV and visible regions. It was found that Henna dye possesses more LHE(%) than Teak and Burmese Ironwood.
Solar cell technology is used to convert solar energy into electrical energy which can be used to power electrical devices. Solar cells are already used to supplement or replace dependence on conventional energy sources in few homes and businesses. There is the potential, however, for further development and wider acceptance of solar cell use to be the answer to the growing energy situation. Incoming photons from the sun excite electrons in the TiO2/anthrocyanin dye complex. These electrons are transmitted through the SnO conductive coating to the multimeter. Electrons come from the multimeter back into the conducting SnO coating on the carbon (soot coated) plate which donates electrons to the KI3 electrolyte. This reduces the electrolyte, which donates the extra electrons to the TiO2/dye complex, completing the cycle of electron flow . Anthocyanins are a subclass of molecules known as flavonoids that are responsible for the brilliant red, orange, and blue colours of most fruits and flowers. Anthocyanidins lack the sugar component of the parent anthocyanin. Six of the anthocyanidins that occur most commonly in nature are pelargonidin, cyanidin, peonidin, delphinidin, petunidin, and malvidin. Anthocyanins are the mono
Anthocyanin, flavonoids from natural sources has been used as sensitizers in DSSCs and recorded low solar energy efficiency conversion  -. DSSCs change cheap energy from the sun to electricity established upon different sensitivities in band gap of dye sensitizers and electrolytes . This process involves several subsystems whose work in cycle is in conjunction with the surface of adsorption of the dye deposited on a sem- iconductor surface that receives near IR photons and visible region of light. It pumps these incident electrons into the conduction band of the semiconductor. Performance of the DSSC is based on the band gap of materials like TiO 2 , electrolytes and the dye sensitizer. TiO 2 is ideal because it has ability to withstand constant electron