ZnO-based Dye-sensitized Solar Cells Research Articles

Performance evaluation of ruthenium complexes and organic sensitizers in ZnO-based dye-sensitized solar cells

Ruthenium (Ru) dyes are a well-known player in the field of dye-sensitized solar cells (DSSCs) due to their high efficiency and excellent stability. Their properties and complexes have been studied for almost three decades. Although these sensitizers show better performances, their high cost makes these third-generation solar devices less economical. Organic dyes have recently been explored as an alternative to Ru-based dyes due to their easy and low-cost synthesis. A comparative performance evaluation of Ru complexes and dicyanoisophorone and rhodanine organic dyes in ZnO-based DSSCs is here reported. All the Ru complexes showed better performance in comparison to organic dyes except R-4. Among the Ru sensitizers, R-3 exhibited the highest efficiency of 1.21% followed by R-2, which is attributed to the presence of several anchoring groups such as carboxyl, nitro and amine. However, the presence of more nitrogen-based groups has drastically reduced the performance as observed for R-4, which is the least performing dye among the Ru-based ones. On the contrary, organic sensitizers S-06 and P-4 revealed to be less efficient with respect to R-3 owing to the presence of only one anchoring group and weak photoanode/dye interaction.

Experimental and theoretical studies on improving the efficiency of ZnO-based dye-sensitized solar cells using single-layer anti-reflective coating

The effect of a single-layer anti-reflective coating (ARC) on ZnO-based dye-sensitized solar cells (DSSCs) is theoretically predicted and verified by experimental fabrication. By the transfer matrix method (TMM), the absorption of the DSSC with and without the single-layer ARC is calculated and the improvement in short-circuit current density (∆ Jsc%) is estimated. The optimized thickness of the ARC required to obtain maximum improvement in the short-circuit current density (∆ Jsc%) is determined. By employing ARC with the calculated optimized thickness, the fabrication of spin-coated ZnO-based DSSCs is carried out. The structural and optical parameters are studied using XRD analysis and UV absorption spectra. The efficiency of the DSSC with and without the ARC is measured by intensity-modulated photocurrent and photovoltage spectroscopy. The theoretically predicted efficiency of the DSSC with and without ARC agrees well with the experimental values that provide insights about improving the electrical performance of the DSSC by the ARC.

Analysis of charge transport resistance of ZnO-based DSSCs because of the effect of different compression temperatures

This article represents a research study about the effect of compression temperature on the performance of Zinc Oxide (ZnO)-based dye-sensitized solar cell (DSSC). To find the optimum compression temperature, the electrodeposited photoanodes are subjected to compression at 60 MP with various compression temperatures ranging from room temperature to 80 °C. The performance analysis involved the analysis of Electrochemical Impedance Spectroscopy (EIS) and photocurrent-voltage (I-V) data under dark and illuminated conditions. The EIS data are examined to gain insights into the electron transport mechanism and validate the cell's performance under optimum compression temperature. The findings of this study demonstrate that cells prepared at 60 MP with a compression temperature of 70 °C show the most favorable photovoltaic performance compared to cells prepared at other compression temperatures. Thickness measurement confirms that increasing the compression temperature ensures a compact layer of photoelectrode. A compression temperature greater than 70 °C causes several defects on the photoelectrode surface, as confirmed by the Scanning Electron Microscopy Image. EIS and I-V data confirm that the cell prepared at 60 MP and 70 °C heating gives comparatively lower series resistance and higher shunt resistance. Though the series and shunt resistance exhibited different values under dark and illumination conditions, their trends remained consistent. Under this optimized compression temperature the cells achieved a maximum efficiency (η) of 2.78%, accompanied by an open circuit voltage (Voc) of 0.58 V, a photocurrent density (Jsc) of 8.87 mA/cm2, and a fill factor of 0.54.

Controlling the Layer Thickness of Zinc Oxide Photoanode and the Dye-Soaking Time for an Optimal-Efficiency Dye-Sensitized Solar Cell

Dye-sensitized solar cells (DSSCs) were developed by exploiting the photovoltaic effect to convert solar energy into electrical energy. The photoanode layer thickness significantly affects the semiconductor film’s ability to carry electronic charges, adsorb sensitizing dye molecules, and lower the recombination of photo-excited electrons injected into the semiconductor. This study investigated the dependence of the zinc oxide (ZnO) photoanode thin-film thickness and the film soaking time in N719 dye on the photocurrent–voltage characteristics. The ZnO photoanode was applied to glass using the doctor blade method. The thickness was varied by changing the scotch tape layers. The ZnO-based DSSC attained an efficiency of 2.77% with three-layered photoanodes soaked in the dye for three hours, compared to a maximum efficiency of 0.68% that was achieved with three cycles using the dip-coating method in other research. The layer thickness of the ZnO photoanode and its optimal adsorption time for the dye are important parameters that determine the efficiency of the DSSC. Therefore, this work provides important insights to further improve the performance of DSSCs.

Influence on the efficiency of dye-sensitized solar cell using Cd doped ZnO via solvothermal method

In this report, the transition metal Cd doped ZnO nanoparticles synthesized by solvothermal irradiation method was used to fabricate ZnO-based dye-sensitized solar cells as photo sensitizers of Terminalia catappa fruit using ethanol as solvent. These prepared metal oxide semiconductor nanoparticles were studied by XRD, FE-SEM, TEM, FTIR, UV–Visible, XPS and DC electrical conductivity. Electrochemical parameters of open circuit voltage, short circuit current density, and fill factor were calculated using J-V characterization. The effect of Cd doping on the efficiency of ZnO-based DSSC is investigated, which results in enhanced DSSC light harvesting efficiency calculated. This obtained result confirms that the doping of ZnO nanoparticles is a valuable material for increasing the corresponding efficiency of a solar cell application.

Influence of Redox Couple on the Performance of ZnO Dye Solar Cells and Minimodules with Benzothiadiazole-Based Photosensitizers.

ZnO-based dye-sensitized solar cells exhibit lower efficiencies than TiO2-based systems despite advantageous charge transport dynamics and versatility in terms of synthesis methods, which can be primarily ascribed to compatibility issues of ZnO with the dyes and the redox couples originally optimized for TiO2. We evaluate the performance of solar cells based on ZnO nanomaterial prepared by microwave-assisted solvothermal synthesis, using three fully organic benzothiadiazole-based dyes YKP-88, YKP-137, and MG-207, and alternative electrolyte solutions with the I-/I3 -, Co(bpy)3 2+/3+, and Cu(dmp)2 1+/2+ redox couples. The best cell performance is achieved for the dye-redox couple combination YKP-88 and Co(bpy)3 2+/3+, reaching an average efficiency of 4.7% and 5.0% for the best cell, compared to 3.7% and 3.9% for the I-/I3 - couple with the same dye. Electrical impedance spectroscopy highlights the influence of dye and redox couple chemistry on the balance of recombination and regeneration kinetics. Combined with the effects of the interaction of the redox couple with the ZnO surface, these aspects are shown to determine the solar cell performance. Minimodules based on the best systems in both parallel and series configurations reach 1.5% efficiency for an area of 23.8 cm2.

Influence of ZIF-8 modification on performance of ZnO-based dye-sensitized solar cells

Influence of ZIF-8 modification on performance of ZnO-based dye-sensitized solar cells

Fabrication and photoanode performance of ZnO nanoflowers in ZnO-based dye-sensitized solar cells

ZnO photoanodes consisting of nanoflowers were successfully synthesized on FTO substrates in two steps using the seed layer-hydrothermal method. To control the morphological and photovoltaic properties of ZnO thin films, three types of photoanodes were fabricated in the presence of NH3 (C1), NH3-PEG (C2) and NH3-PVA (C3). The morphological and structural properties of the produced photoanodes were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). Using these photoanodes, six different types of dye sensitized solar cell (DSSC) were obtained with Ruthenium Dye (Z907) and two different electrolytes. Photovoltaic (PV) and electrochemical impedance spectroscopy (EIS) characterization of DSSCs were performed. The maximum energy conversion efficiencies of these photoanodes in the presence of NH3, NH3-PEG and NH3-PVA were obtained as 1.57, 0.70 and 1.61, respectively, for the same type of electrolyte (AN50) under 100 mW/cm2 illumination.

Different anchoring ligands for Ru complexes dyes and the effect on the performance of ZnO-based Dye-Sensitized Solar Cell (DSSC): A computational study

Chemical modifications allow to design new sensitizers for Dye-Sensitized Solar Cells (DSSC). This investigation aims to analyze new Ru complexes-based sensitizers for ZnO-based DSSC by substituting carboxylic acid groups with phendione (PHEN) and acetylacetone (ACAC) anchoring ligands while using isothiocyanate (NCS) and cyanide (CN) as ancillary ligands. The electronic structure of these complexes and their charge transport mechanism were analyzed using Time-Dependent Density Functional Theory (TD-DFT). The obtained results show that PHEN is a good substituent in these complexes since the obtained HOMO-LUMO gaps are close to 1.9 eV. Additionally, based on the donor–acceptor properties, Ru-PHEN complexes are better electron acceptor groups, whereas Ru-ACAC present better electron donor properties for electronic transporting processes with ZnO and the electrolyte. This theoretical study is a practical guide to the molecular engineering of alternative dyes used in ZnO-based DSSC.

Enhancement in Photovoltaic Performance of Solar Cells by Electrostatic Adsorption of Dyes on ZnO Nanorods.

ZnO nanorods were formed by chemical bath deposition on fluorine–doped tin oxide (FTO) glass and the photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) was investigated. A DSC with 8 h-grown ZnO nanorods showed a higher power conversion efficiency (PCE) than devices with 4, 6, and 10 h-grown ones. Further improvement in PCE was achieved in a cell with a silver-ion-deposited ZnO/FTO electrode. By deposition of Ag+ on the surface of the 8 h-grown ZnO nanorods, the dye-loading amount increased by approximately 210%, compared to that of pristine ZnO nanorods, resulting in a 1.8-times higher PCE. A DSC with the pristine ZnO/FTO electrode showed a PCE of 0.629%, while in a device with the silver-ion-deposited ZnO/FTO, the PCE increased to 1.138%. In addition, interfacial resistance at the ZnO/dye/electrolyte was reduced to approximately 170 Ω from 460 Ω for the control cell with the pristine ZnO/FTO. We attributed the higher dye-loading amount in the silver-ion-deposited ZnO/FTO to the electrostatic attraction between the positively charged ZnO and carboxylate anions (–COO−) of the N719 dyes.

Fabrication and Photoanode Performance of Zno Nanoflowers in Zno-Based Dye-Sensitized Solar Cells

Fabrication and Photoanode Performance of Zno Nanoflowers in Zno-Based Dye-Sensitized Solar Cells

Analysis and Prediction of Hydrothermally Synthesized ZnO-Based Dye-Sensitized Solar Cell Properties Using Statistical and Machine-Learning Techniques.

Dye-sensitized solar cells (DSSCs) are one of the most versatile and low-cost solar cells. However, DSSCs are prone to low power conversion efficiency (PCE) compared to their counterparts, owing to their different synthesis parameters and process conditions. Therefore, designing efficient DSSCs and identifying the parameters that control the PCE of DSSCs are a critical tasks. We have collected data from hydrothermally synthesized DSSCs in the present work, published from 2005 to 2020. In line with publishing trends in the said period, we evaluate ZnO as a popular photoactive material for DSSC applications. We further analyzed the performance of hydrothermally synthesized ZnO DSSCs using different statistical techniques and provided some significant insights. We further applied the machine-learning technique with a decision tree algorithm to understand and discover the possible set of rules and heuristics that govern the morphology of the hydrothermally grown ZnO. In addition, we also employed supervised and unsupervised machine-learning models using conventional decision trees and classification and regression trees, respectively, to identify the dependence of the PCE of ZnO DSSCs on the different synthesis parameters. The reported work also evidences the PCE predictions of the ZnO DSSCs by using random forest and artificial neural network algorithms. The results substantiate that the random forest and artificial neural network algorithms successfully predict the PCE of the ZnO DSSCs with reasonable accuracy. Thus, we present a novel approach of applying statistical analysis and machine-learning algorithms to understand, discover, and predict the performance of DSSCs. We recommend extending the said know-how to other solar cells to identify rules and heuristics and experimentally realize highly efficient solar cells in shrinking manufacturing windows with a cost-effective approach.

Fruit peels pigment extracts as a photosensitizer in ZnO-based Dye-Sensitized Solar Cells

Two of the most serious problems that we encounter today are the energy crisis and global warming. It has, therefore, become essential for a quest for clean and renewable energy sources, as the lasting solution for these problems. This paper presents the natural pigments from the facile extraction of fruit peels of Musa paradisiaca, Mangifera indica, Punica granatum, and Ananas comosus and their conversion efficiency in dye-sensitized solar cells (DSSCs). The zinc oxide (ZnO) photo-anode film was prepared and its properties were analyzed. Natural extracts were used as photosensitizers for constructing DSSCs. Characteristics of the natural Pigments were analyzed by various spectroscopy techniques. Solar to electrical energy efficiencies of natural dye-based on ZnO DSSCs were evaluated for Musa paradisiaca, Mangifera indica, Punica granatum, and Ananas comosus to be 0.009%, 0.024%, 0.010%, and 0.002%, respectively. The conversion of visible light into electricity resulting in improved photoelectric characteristics was achieved.

Development of photo-anodes based on strontium doped zinc oxide-reduced graphene oxide nanocomposites for improving performance of dye-sensitized solar cells

The goal of this study was to create highly efficient dye-sensitized solar cells (DSSCs) using strontium doped zinc oxide-reduced graphene oxide (Sr-doped ZnO/rGO) nanocomposites. As photo-anodes of DSSCs, ZnO, ZnO/rGO (with weight percent rGO in composites: 0, 0.01, 0.1, 0.5, and 1 wt%) and Sr-doped ZnO/rGO (with Zn1-xSrxO nanoparticle stoichiometry: x = 0, 0.02, 0.04, 0.06 and 0.08) nanocomposites were designed and characterized. AFM, FESEM, XRD, EDS, XPS, PL, and FTIR analyses were used to investigate the morphology and structure properties of prepared nanocomposites. UV–vis spectroscopy and photo-electrochemical measurements were used to investigate the efficiency of prepared photo-anodes. The efficiency (η) and short-circuit photocurrent density (JSC) of DSSCs based on Zn0.92Sr0.08O/rGO nanocomposite were 7.98 % and 18.4 mA cm−2, respectively. The results showed that doping Sr on ZnO/rGO nanocomposites resulted in a wide bandgap energy and increased the values of η, JSC, IPCE, and photo-anode electron transportability. These findings suggest that Sr-doped ZnO/rGO nanocomposites can provide a novel approach for increasing photo-electrochemical activity in ZnO-based DSSCs.

Performance Analysis of Several ZnO-Based Dye-Sensitized Solar Cells With Identical Photoelectrodes, Electrolyte, and Sensitizer

In this work, we have tried to understand the variation of experimentally obtained photovoltaic characteristics (open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF), and conversion efficiency (η)) for multiple dye sensitized solar cells (DSSCs) prepared and characterized under identical experimental conditions. Twenty (20) DSSCs are prepared using ZnO photo-anodes, Pt cathodes, I−/I3− electrolyte, N719 sensitizers, and fluorinated tin oxide-based transparent conducting oxide substrates. ZnO is synthesized wet chemically and characterized in terms of its phase, morphology, thermal stability, optical behavior for the preparation of photoanodes. The photovoltaic characteristics are estimated under the exposure of simulated solar light (power of incident light 100 mW cm−2 from air mass 1.5 G). Relative standard deviation values are estimated for each photovoltaic parameter and the trends of deviations are studied for the developed cells. Finally, the charge transfer dynamics of cells having maximum and minimum photoconversion efficiencies are investigated through electrochemical impedance spectroscopy.

Comparative hydrothermal synthesis of CeO2 crystals for use in light-scattering layers of dye-sensitized solar cells

Light-scattering octahedral CeO2 particles could be used to increase the short-circuit photocurrent density of ZnO-based dye-sensitized solar cells.

Effect of precipitating agents on the performance of ZnO nanoparticles based photo-anodes in dye-sensitized solar cells

Dye-Sensitized Solar Cell (DSSC), as a unique non-conventional energy system, is rapidly gaining more attention from researchers. Efforts to fabricate photovoltaic devices with high conversion efficiencies at low cost with a simple fabrication process have prompted researchers to continuously work on different components of DSSC. This research focuses on the effect of precipitating agents, sodium hydroxide, and ammonium hydroxide on the fabrication of ZnO-based DSSCs. ZnO nanoparticles were prepared and characterized based on structural and microstructural analyses, UV-absorption and reflectance spectroscopy, and FTIR analysis, as one of the potential semiconductor photo-anodes for DSSCs. The uniformly prepared films using the doctor blade technique were soaked in Ruthenizer 535-bisTBA dye solutions for sensitization. The films were assembled and current-density characteristics measurements were taken using a solar simulator at 100 mW/cm2 and 25 °C. The effect of precipitating agents on the performance of the fabricated DSSC was studied. Photovoltaic performance evaluation of DSSCs using N719 dye as a sensitizer revealed that the open-circuit voltage (VOC) ranged between 0.535 and 0.719 V, and the short-circuit photocurrent density (JSC) was in the range of 3.621 to 5.875 mAcm−2. The highest conversion efficiency of 2.43 % was recorded for the synthesized ZnO semiconductor photo-anode using NaOH as the precipitating agent.

Characterization of dye-sensitized solar cells based on various CaCO3-doped ZnO photoanodes prepared using wet powder mixing and grinding

The effects of different doping contents of calcium carbonate (CaCO3) on the performance of zinc oxide (ZnO)-based dye-sensitized solar cells (DSSCs) have never been discussed. In this paper, ZnO nanopowder and CaCO3 nanopowder at different weight percentage concentrations (0–9 wt%) were made into the photoanodes of DSSCs using the wet powder mixing and grinding method. The CaCO3/ZnO DSSC doped with 3 wt% CaCO3 had the highest short-circuit current density (4.35 mA/cm2) and photovoltaic conversion efficiency (1.18%), higher than the short-circuit current density of the reference ZnO-based DSSC by 52%, and the photovoltaic conversion efficiency by 46%. It was found that the photoanodes prepared by doping a small amount of CaCO3 into ZnO could enhance the photoelectric properties of ZnO-based DSSC effectively. The characterization of the CaCO3/ZnO DSSCs were carried out via the measurement of scanning electron microscope (SEM), contact angle (CA) and photocurrent density-voltage (J-V) characteristics. A theoretical background based on charge transport and interfacial recombination was provided to elucidate the process and was tried to explain the mechanism of CaCO3/ZnO DSSC. Although the efficiency of CaCO3/ZnO DSSC still has much room for improvement, the related processes and mechanisms behind this device have considerable research and/or reference value.

Highly Efficient Dye-Sensitized Solar Cells with Composited Food Dyes

As a representative of third-generation solar cells, dye-sensitized solar cells (DSSCs) possess the advantages of easy fabrication and relatively high power conversion efficiency (PCE). However, the commonly used dyes (such as N719, N3, C217, and Z907) in DSSCs are expensive and toxic. Herein, the nontoxic food dyes, including Amaranth, Sunset Yellow, and Erythrosin B, were explored for DSSC applications. Particularly, this is the first study to combine two of three nontoxic food dyes for DSSCs, leading to a remarkable increase of PCE. Furthermore, a correlation was identified between the PCE and the composition of the combined dyes. The ZnO-based DSSCs with combined Amaranth and Erythrosin B dyes exhibited the highest PCE of 2.64%.

Application of Co-Mo bimetal/carbon composite in dye-sensitized solar cells and its research on synergy mechanism

Bimetal/carbon aerogels have many advantages, such as nano-scale properties, low density, large specific surface area, and high porosity, but their application in dye-sensitized solar cells (DSSCs) as a counter electrode (CE) instead of noble metal Pt is relatively rare. In this paper, a low-cost sodium alginate was used to obtain a Co-Mo bimetal/carbon composite through a simple and controlled carbonization process. Using them as CEs of ZnO-based DSSCs, the filling characteristics of dye can be effectively improved. When the Co2+/Mo2+ molar ratio is 1:3, the photoelectric conversion efficiency of Co-Mo bimetal/carbon composite–based DSSCs is close to the photoelectric conversion efficiency of Pt based, which is considered to be the result of the synergy of the carbon and two metal ions.