Dye Solar Cells Research Articles

Effect of low-temperature underwater plasma produced of new properties of Mo–Ti mixed oxide composites for electron transport layer in the dye-sensitized solar cells

TiO2-based composites are potential materials for dye solar cells. Here we report a new method for synthesizing a new composite material based on molybdenum and titanium oxides. Low-temperature underwater direct current plasma is used as a synthesis method, and Mo and Ti wires were as electrodes. The polarity of the electrode affects the nature of the array. It was found that with the positive polarity of the molybdenum electrode (anode), MoO3 decorated with rutile is formed. The mixed-phase TiO2 decorated MoOx (x = 2.75–2.85) is formed by the negative polarity Mo of the electrode (cathode). The synthesized composites show improved characteristics in the photocurrent response and photovoltaics.

Study of Supercapacitors for Use in Dye Sensitized Solar Cells

The storage of energy generated by photovoltaic system is one problem of it. In this aspect, integrated energy conversion and storage systems, IECSS, using supercapacitors are presented as a solution. Dye sensitized solar cell becomes a main candidate for use in IECSS due its variety of applications. Recent studies shown that zinc oxide (ZnO) is a natural candidate for use in solar cells and supercapacitor due to its high energy density of the order 650 A g-1. The aims of this paper were: i) the study of the influence of the morfology of nanostructured ZnO nanoparticles obtained by the hydrothermal method using distincts complexing agents: etylenediaminetetraacetic acid (EDTA); hexamethyltetramine (HMT) and diaminometanal (urea), besides commercial ZnO; ii) study of the ZnO and activated carbon at ratio X:Y of 10:90, 20:80 and 30:70 in proportion of mass (%) in the preparation of electrodes. The commercial ZnO, which presents particles with spherical and porous morphology, presented the best capacitance result 8.38 Fg-1 at 10:90 ratio, that demonstrates the ZnO is an excellent candidate for material for supercapacitor coupled with dye solar cell.

Extreme sensitivity of dye solar cells to UV‐induced degradation

AbstractPresent practice to avoid harmful effects of UV light on dye solar cells (DSC) is to use a UV filter. However, we show here that a standard 400 nm UV cutoff filter offers inadequate protection from UV‐induced degradation. DSCs that were exposed to only visible light by LED lamps maintained 100% of their initial efficiency after 3000 hours of exposure, whereas the efficiency of DSCs subjected to full light spectrum (Xenon arc lamp) with an efficient UV filter dropped down to 10% of their initial performance already after 1500 hours. Optical analysis of the UV filter confirmed that the amount of light transmitted below 400 nm was negligible. These observations indicate that (a) DSCs can be very sensitive to even minor amount of UV and (b) eliminating the effects of UV light on DSC stability cannot easily be avoided by a UV filter on top of the cell. A detailed analysis of the degradation mechanisms revealed that the culprit to loss of performance was accelerated loss of charge carriers in the electrolyte of the DSCs—a typical symptom of UV exposure. These results suggest that commonly used stability tests under LED illumination are insufficient in predicting the lifetime of DSCs in outdoor conditions. Instead, for such purpose, we recommend solar cell stability to be tested with a full light spectrum and with a suitable UV filter.

Effects of pure and mixed stabilizers on opto-electrical properties and morphology of TiO2 nanoparticles synthesized by sol-gel method

Titanium dioxide (TiO2) is acknowledged as the most advanced nanomaterial. It has been used in certain application, such as semiconductor, photocatalyst, dye solar cells, paints, dyes, cosmetics, antifogging coatings, self-cleaning windows, etc. Although TiO2 nanoparticles occur naturally in mineral form, but the particles are also being synthesized through different well-known techniques. The past literature reveals that sol-gel methodology is considered as the most attractive and suitable technique for the preparation of such kind of nanoparticles. This article reports the effects of three different stabilizers (HCl, HNO3 and mixture of HCl+HNO3) on the morphological and opto-electrical properties of TiO2 nanoparticles. The nanoparticles of TiO2 were synthesized through sol-gel process by using titanium tetra isopropoxide (TTIP) as precursor in a solution of deionized water and isopropanol at 80 °C under constant stirring. The synthesized TiO2 nanoparticles were characterized through X-ray Diffractometry (XRD), Scanning electron microscopy (SEM) and UV-Visible spectrophotometry. The grain size with perfect crystallinity obtained through XRD were in good agreement with SEM results. The grain size of the prepared TiO2 nanoparticles using HCl, HNO3 and (HCl+HNO3) were 3 nm, 2.8 nm and 3.3 nm, respectively. The optical characterization of TiO2 revealed band gap energy values of 4.10 eV, 6.16 eV and 6.14 eV corresponding to absorption edges at 302 nm, 201.2 nm and 201.73 nm, respectively. The smaller grain sizes were having larger band gaps.

Computational design of new organic (D–π–A) dyes based on benzothiadiazole for photovoltaic applications, especially dye-sensitized solar cells

A theoretical study on four organic dyes based on bis(4-hexyloxy)triphenylamine as donor and electron acceptor cyanoacrylic acid with a donor–π–acceptor structure (D–π–(D–A–)–A) using DFT/DFT (TD-DFT)/6-31G(d,p) having a difference of π spacer was designed. The theoretical study of the structural, electronic and optical properties of these dyes (D1, D4) suggests that these materials would be excellent sensitizers as a candidate for the production of dye solar cells, due to the efficient photoinduced electron transfer and strong absorption as well as the electronic properties (HOMO, LUMO, Egap) low band gap, The improved light-harvesting efficiency and free energy change of electron injection (ΔGinject), of new designed sensitizers revealed that these materials would be excellent sensitizers. This theoretical designing paves the way for experimentalists to synthesize more efficient sensitizers for solar cells.

Sustainable Organic Dyes from Winemaking Lees for Photoelectrochemical Dye-Sensitized Solar Cells

During the last two decades, Dye Sensitized Solar Cells (DSSCs) have received a great deal of attention as a promising, low-cost alternative to conventional silicon photovoltaic devices. Natural dye molecules can be used as a sensitizer for their low cost, good light absorbance, easy preparation process, and biodegradability. In this study, dyes were obtained from wine lees, the last by-product of winemaking process, supplied by a venetian winery (Italy). Polyphenols, like tannins and anthocyanins, which were extracted from winemaking lees, were adsorbed on a nanostructured ordered mesoporous titanium dioxide, previously treated at different temperatures (400–600 °C). Both dyes and titania semiconductor samples were studied with different techniques. The tests were carried out on prototypes to evaluate the cell power and the photocurrent generated under simulated solar light irradiation. The obtained solar energy conversion efficiencies are comparable to those that were reported in literature by using organic dyes extracted from vegetables, fruits, and plants. It is significant that these dyes are largely available and cost effective, since recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells to generate green electricity and transforming agri-food waste into a resource.

Scalable photoelectrochromic glass of high performance powered by ligand attached TiO2 photoactive layer

A scalable photoelectrochromic (PEC) glass which can be darkened on exposure to sunlight and return to its original clear state in the absence of sunlight without any expensive materials like ruthenium dye or transparent conductive oxide was fabricated. The PEC glass is composed of light absorbing layer of ligand attached titanium oxide, color changing layer of tungsten oxide and the electrolyte containing redox mediator. This work reports, for the first time, on an application of salicylic acid attached TiO2 photoactive layer for PEC devices. The applicability of various salicylic acid derivatives attached TiO2 films in PEC device is individually investigated in dye solar cells. Among various salicylic acid derivatives studied, 5-methylsalicylic acid showed the best performance in terms of charge generation for coloration of WO3. By using 5-methylsalicylic acid instead of ruthenium dye, lower cost, higher stability, and simpler electrolyte composition have been realized. The changes in transmittance for coloration (ΔTC) depend on the thickness of WO3 and TiO2 in this device. Thus, we changed the thickness of WO3 and TiO2 to get the highest variation of transmittance for coloration. The preliminary optimization of PEC device exhibits ΔTC of 40.8% at 550 nm, the wavelength most sensitive to the human eye, and of 64.3% at 700 nm.

Plasmonic nanostructures of SnO2:Sb thin film under gamma radiation response

Abstract This paper is a part of a natural dye solar cell project. Conductive transparent oxide (CTO) films have been deposited onto preheated glass substrates using a spray pyrolysis technique. The optical, electrical, structural properties as well as thermal annealing and gamma radiation response were studied. The average optical energy gap of doped films for direct allowed and direct forbidden transitions were found to be 3.92 and 3.68 eV, respectively. The plasmon frequency and plasmon energy after doping were found to be 3.48 × 1014 s −1 and 0.23 eV. The negative absorbance of the doped film was observed in UV-Vis range after applying both thermal annealing and γ-dose irradiation with 22 kGy. The negative refractive index of the doped film in UV range (220 – 300 nm) is promising for optical applications. The electron mobility μe reached a maximum of 27.4 cm2 V−1 s−1 for Sb concentration of 10 %. The corresponding resistivity ρ, and sheet resistance Rs reached their minimum values of 1.1 × 10−3 Ω cm and 35 Ω sq−1, respectively. The dopant concentration has been increased from 4.13 × 1019 to 2.1 × 1020cm−3. The doped film was found to exhibit three diffraction peaks associated with (2 2 2), (2 0 0), and (2 1 1) reflection planes, of which the peak of (2 2 2) of Sb2O3 and the peak of (2 0 0) were very close.

Photovoltaic properties of the flavonoid‐based photosensitizers: Molecular‐scale perspective on the natural dye solar cells

AbstractThe molecular modification and the effects of the gas and water media on the ability of some flavonoids as the photosensitizers in the natural dye‐sensitized solar cells were theoretically investigated. According to the results, water increases the electrophilicity of the dyes and weakens the dye/TiO2 coupling, prohibiting the electron injection toward TiO2. A longer path for charge transfer and a less electron‐hole overlap for dihydroxychromens elevate the electron transfer more efficient than trihydroxychromen‐based flavonoids. However, the presence of water molecules within an increment in the OH groups in the flavonoid structures improves their spectroscopic properties, which is related to decrement in the gap of the frontier molecular orbitals and increment in the oscillator strength. Also, such favorable structural effects and influence of the water medium on the polarizability and excited‐state lifetime have emerged. According to the energy conversion efficiency, water is a favorable solvent for dihydroxychromen‐based flavonoids. Finally, different analyses on the structural geometries, excited‐state, lifetime within the kinetics, and dynamics of the photovoltaic processes were performed and discussed.

Design and fabrication of hybrid carbon dots/titanium dioxide (CDs/TiO2) photoelectrodes for highly efficient dye-sensitized solar cells

Hybrid carbon dots/titanium dioxide (CDs/TiO2) photoelectrodes for use in high-performance dye-sensitized photovoltaic solar cells were obtained by a facile one-step hydrothermal approach. The structural, morphological, and optical properties of the as-obtained samples were analyzed by powder X-ray diffraction analysis, transmission electron microscopy, Raman spectroscopy, ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy, and photoluminescence spectroscopy, revealing anatase crystal structure with individual spherical molded nanoparticles for both TiO2 and the composite samples. The size of the nanoparticles ranged from 30 to 40 nm, being consistently decorated on the carbon dots. The CDs/TiO2 samples exhibited enhanced surface area (112 m2/g) and pore size (30–35 nm) compared with bare TiO2 (77 m2/g and 42–48 nm), which is invaluable for improving solar cell efficiency. The J–V characteristic illustrated that the CDs/TiO2 photoanode resulted in high photovoltaic conversion efficiency (PCE) of 15.5% compared with 7.8% when using bare TiO2. These results suggest that incorporation of carbon dots enhanced the PCE of the cells using bare TiO2. A mechanism for this improvement is also proposed in detail.

Stability of cobalt complex based dye solar cells with PEDOT and Pt catalysts and different electrolyte concentrations

Here a 2000-h light-soaking stability test is reported for cobalt complex based dye solar cells using Y123 organic dye with either platinum or poly(3,4-ethylene dioxythiophene) as counter electrode catalyst, and two different Co(III) electrolyte concentrations. Both the Co(III) concentration and the counter electrode catalyst affected the device stability. Higher Co(III) concentrations were found to slow down the degradation process with both catalyst materials. Different degradation behavior was also identified for devices with different catalyst materials.

Improved performance of dye-sensitized solar cells upon sintering of a PEDOT cathode at various temperatures.

Poly(3,4-ethylenedioxythiophene) (PEDOT) thin films have attracted considerable attention as cathodes for dye-sensitized solar cells (DSSCs) due to their air-stable, light-weight and conductive nature. To demonstrate their thermal stability as cathodes, PEDOT thin films coated via electrochemical polymerization on fluorine doped tin oxide (FTO) plates were sintered at different temperatures (50, 100, 150, 200, and 300 °C) for 1 h and a comparison was made with the as-prepared PEDOT thin films. We observed a negative temperature coefficient effect up to 200 °C along with lower surface roughness upon increasing the sintering temperature. Dye solar cells were fabricated using PEDOT thin films (sintered at different temperatures) and as-prepared PEDOT cathodes, and their respective performances were studied. The results showed increased efficiency with the increase in sintering temperatures of the cathode up to 200 °C (η = 4.33%) under the present experimental conditions. Cathodes sintered at 300 °C had poor electrochemical behavior and J–V performance, which may be due to polymer degradation.

Using Grätzel cells as Arduino-controlled photosensors: proposals for the insertion of nanoscience and nanotechnology in classroom

Abstract In this work, the production of Gratzel cells, also called dye-sensitized solar cells (DSSCs), their use as Arduino-controlled photosensors, and their application for the inclusion of nanoscience and nanotechnology in educational activities are reported. Gratzel cells were manufactured using titanium dioxide (TiO2) nanoparticles, fluorine-doped tin oxide (FTO) coated glass, KI/I2 solution, graphite, and grape juice as a sensitizer. Among the educational proposals suggested for the integrated use of DSSCs and Arduino, the assembly of a photometer for applications in optics and the construction of a light distance sensor stand out. As a suggestion for further studies, the UV-Vis spectra of titanium dioxide nanoparticles and grape juice were obtained and analyzed in order to illustrate how a deeper understanding of the materials used in DSSCs can provide answers about the mechanisms responsible for the detection properties of Gratzel cells in the context of the nanoscopic world.

Standardizing Performance Measurement of Dye-Sensitized Solar Cells for Indoor Light Harvesting

During the last five years the demand of indoor photovoltaic (IPV) technology is growing rapidly for the Internet of Things. Until now, there is no standardized measurement methodology for IPV devices. So, it is very hard to estimate device efficiency accurately in indoor illuminating condition. This is one of the main obstacles for the commercialization of IPV devices. A standardized universal measurement methodology is highly needed. Therefore in this study, a series of N719 dye based dye-sensitized photovoltaic (PV) cells have been fabricated by varying the working electrode thickness. Then, a low irradiance measurement system has been configured to develop an ideal indoor environment with diffused light by adjusting the distance (1.4 m) between the test cell and light source. Furthermore, the inner wall of the measurement system has been covered by white paper. PV cells are tested under the illumination of three different light sources such as cold cathode fluorescent lamp (CCFL), cool white LED (LED 5600 K), and warm white LED (LED 3200 K)), at the same irradiance power intensity (150 μW/cm 2 ) and luminance (500 Lux) values, to standardize the measurement methodology for PV cells in indoor environment. This study shows that, the response of a PV cell to different light sources can be realized more accurately, if the PV cell is tested under the illumination of different light sources at a fixed irradiance power intensity value instead of a fixed luminance value.

A water-based and metal-free dye solar cell exceeding 7% efficiency using a cationic poly(3,4-ethylenedioxythiophene) derivative.

A green, efficient and stable solar cell based only on water and safe and cheap elements of the periodic table is proposed in this work, finally consolidating (also from a sustainability viewpoint) the concept of “artificial photosynthesis” studied for decades by the scientific community. The concept of dye-sensitized solar cells is re-proposed here with a metal-free organic dye, an iodine-based electrolyte in a 100% aqueous environment and a new cathode (cationic PEDOT) synthesized for the first time with the aim of inhibiting the repulsion between the anions of redox couples and the PEDOT:PSS matrix commonly used as the counter-electrode. This elegant setup leads to a record efficiency of 7.02%, the highest value ever obtained for a water-based solar cell and, in general, for a photovoltaic device free of both organic solvents and expensive/heavy metals.

Preparation and Characterization of Tetraphenylporphyrin Dyes

Porphyrin compounds exist widely in nature and are a key part of photosynthesis and photosynthesis. Because of its good photothermal stability and many unique physical and chemical properties, it has been widely used in the research and development of sensitized dye solar cells. As a new type of solar cell, dye-sensitized solar cell has attracted extensive attention and research due to its simple manufacturing process, relatively cheap price, high photoelectric conversion efficiency and environmental protection. In this paper, control experiments were carried out to synthesize tetrabenzoporphyrin with higher yield and purity by changing the solvent and washing solvent. The samples were characterized by uv-vis spectra. The results showed that the tetraphenylporphyrin crystals with better comprehensive effect could be obtained by using ethanol solution as sample solution and distilled water as washing solvent.

Structural modification as the pioneer strategy in competition of the porphyrin dye and perovskite solar cells: From dynamics to kinetics of the photovoltaic processes

Molecular engineering plays a key role in designing efficient dye-sensitized/perovskite solar cells (DSSCs/PSCs). Porphyrins have more favorable spectroscopic properties than AZn(COOH)3 perovskites due to their lower chemical hardness. Also, porphyrins are pioneering photosensitizers in exciton formation/dissociation, kinetically. The presence of Zn2+ and butadiyne as the linker in the porphyrins and the existence of the electron donors of dimethylammonium and formamidinium in the perovskites improve their photovoltaic properties. Porphyrin dimers have a greater charge transfer distance in comparison to the monomers. However, they show less energy conversion efficiency, which may be related to the quenching of the interporphyrin charge transfer. As a consequence, DSSCs based on the porphyrin monomers have a higher efficiency than the studied PSCs.

Electrospun Nanofibers Applied to Dye Solar Sensitive Cells: A Review.

In recent decades, there has been an increase in the research for the development and improvement of dye sensitized solar cells (DSSCs), owing to their singular advantages such as greater efficiency in energy conversion and overall performance in adverse environmental conditions. Therefore, work is carried out to enhance the energy efficiency of the components of the DSSCs: photoanode, counter-electrode, electrolyte, and dye sensitizer layer. Electrospun nanofibers in particular, have showed to be a novel alternative as components in DSSCs, mainly for energy conversion and as collector materials due in part to their tridimensional structure, high contact surface area and conductivity. Moreover, the incorporation of metallic compounds into nanofibers is advantageously employed in the electrospinning technique, owing to their conductivity and optical properties. Therefore, the present work consists of a detailed recompilation of the use of electrospun nanofibers loaded with metallic compounds and their application in DSSCs. The functionality of the components of DSSCs, parameters and experimental conditions of electrospinning, such as the intrinsic aspects in the polymer solution, are discussed and applied to the photoanode, counter-electrode and electrolyte of the DSSC. Lastly, the use of the electrospinning technique in combination with the use of metallic compounds could provide a great approach for the developing of DSSCs, with superior efficiency, high stability and durability.

A facile method to produce TiO2 nanorods for high-efficiency dye solar cells

Highly ordered TiO2 nanorods are considered promising for photoanodes in dye-sensitized solar cells due to their high charge transfer rate of photo-generated electrons, but they often suffer from low specific area, which may lead to a low conversion efficiency. Here, we produce long vertical single-crystalline rutile TiO2-nanorod arrays on fluorine-doped tin oxide conductive glass substrates(FTO)by the hydrothermal method. To further increase the specific area, the TiO2-nanorod arrays are etched in a secondary hydrothermal process by hydrochloric acid. The etching time have a major effect on the nanorod microstructure and on the dye-sensitized solar cells efficiency. The best result is reached with 8 h of etching, which results in a record high conversion efficiency of 11.14 ± 0.12% (certified efficiency 10.3%) under full sunlight illumination (AM 1.5 G, 100 mW/cm2). The record cell has an open voltage of 0.79 V and a short current density of 21.59 mA/cm2. The proposed manufacturing approach of TiO2 nanorods is highly potential for producing high-efficiency dye-sensitized solar cells.

Role of organic cation in modern lead-based perovskites

Hybrid organic-inorganic metal perovskites (ABX3, A- organic cation, B-metal ion, X-halide ion) have shown significant potential as thin-film solar cells or Dye solar cells (DSC) materials. Using a time-dependent density functional theory (TDDFT) study, this work explores the role that the central organic cation plays in defining the optoelectronic and physical properties of metal perovskites. Cubic phases of CH3NH3PbI3, CH3NH3PbCl3, CH3NH3PbICl2, and CH3NH3PbI2Cl perovskite structures are investigated using TDDFT with Gaussian 16. Electronic and optical properties, including transition energy, band gap, IR and absorption spectra and vibrational frequencies are examined. It is observed that the organic cation reduces the unit cell volume of the outer metal halide structure from approximately 9–20% for different perovskite materials. The peak optical absorption also correspondingly decreases by a significant margin, ranging from about 40–60%.