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Alkyl Group Wrapped Unsymmetrical Squaraine Dyes for Dye-sensitized Solar Cells: Branched Alkyl Chains Modulate the Aggregation of Dyes and Charge Recombination Processes
摘要： Electron transfer processes at the interfaces dictate the factors to improve the photovoltaic parameters such as open-circuit voltage (Voc) and short-circuit current (Jsc) of a dye-sensitized solar cell (DSSC) device besides selecting a set of suitable anode, dye, electrolyte and cathode materials. Inefficient charge injection process at dye-TiO2 interface and charge recombination at the TiO2-dye/electrolyte interface have detrimental effects in improving both Jsc and Voc. Hence tailoring the factors that governs to improve the Jsc and Voc will be an ideal approach to get the desired sensitizers with good device efficiencies. Squaraines are far-red active zwitterionic dyes, has high molar extinction coefficient along with unique aggregation properties due to the larger dipole moment associated with it. Here we report a series of unsymmetrical squaraine dyes, SQS1 to SQS6, with systematic variation of alkyl groups at sp3-C and N-atoms of indoline unit that was away from the anchoring group to control the dye-dye interactions on the TiO2 surface. The branched alkyl groups help to modulate the self-assembly of sensitizers on the TiO2 surface besides passivating the surface that helps to avoid the charge recombination processes. Light harvesting efficiency (LHE) and cyclic voltammetry studies of dye-sensitized TiO2 electrode indicated that the aggregation and charge hopping process between the dye molecules can be modulated, respectively by systematically increasing the number of carbon atoms in the alkyl groups. Such variation in the branched alkyl group helps to enhance the Voc from 672 (SQS1) to 718 mV (SQS6), Jsc from 7.95 (SQS1) to 12.22 mA/cm2 (SQS6), with the device efficiency ranging from 3.82% to 6.23% without any coadsorbent. Dye SQS4 has achieved highest efficiency of 7.1% (Voc = 715 mV, Jsc = 13.05 mA/cm2) with coadsorbent chenodeoxycholic acid (CDCA) using iodine (I-/I3 -) electrolyte compared to its analogs. Analysis of IPCE profile indicates that the major contribution of photocurrent generation is from the aggregated squaraine dyes on TiO2.
关键词： Un-symmetrical squaraines,charge recombination,charge injection,aggregation of dye,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Function of <scp>TiCl</scp><sub/>4</sub> Posttreatment in Photoanode
摘要： Energy is the key factor for any living creature to exist in this universe. The advent of industrialization and increase in population have led to a surge in the crisis for energy. The reduction of our dependence on fossil fuels (oil, coal, and natural gas), as well as the evolution towards a cleaner future, requires the large deployment of sustainable renewable energy sources. Among them solar energy is the most abundant and also available throughout the year. Moreover, the solar energy has the greatest potential to fulfill the thirst for energy and the need for innovation of clean and eco-friendly technologies. In this perspective, developing solar cells is one of the best approaches to convert solar energy into electrical energy based on photovoltaic effect. Solar cells based on crystalline silicon and thin film technologies are often referred to as first- and second-generation solar cells. The demerits in that are the limited availability and the cost of silicon. An emerging third-generation photovoltaics have been developed as an alternate to it. These include Dye-sensitized solar cells (DSSCs), organic photovoltaic, quantum dots and recently perovskite solar cells. DSSCs based on nanocrystalline TiO2 as a photo-anode have attracted a lot of scientific and technological interest since their breakthrough in 1991 [1]. The two main functional aspects of charge generation and transport are no longer combined in one material but separated in different materials, i.e. a sensitizing dye, a wide-band-gap semiconductor (TiO2), and a liquid redox electrolyte [2].
关键词： photoanode,TiO2,dye-sensitized solar cells,electron transport,TiCl4 posttreatment,dye adsorption,photocurrent generation
更新于2025-09-12 10:27:22
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A new type of multibenzyloxy-wrapped porphyrin sensitizers for developing efficient dye-sensitized solar cells
摘要： Porphyrin dyes have been widely used for the fabrication of efficient dye-sensitized solar cells (DSSCs). However, dye aggregation and charge recombination still exert negative effects on photovoltaic performance, resulting in unsatisfactory power conversion efficiencies (PCE). Herein, we report a new class of porphyrin sensitizers XW52 and XW53 employing four benzyloxy groups to wrap the porphyrin cores. As a result, an efficiency of 7.6% was obtained for XW52, with Voc and Jsc of 668 mV and 16.63 mA cm-2, respectively. Compared with XW52, an additional 2,6-dialkoxyphenyl group has been introduced to the N-atom of the phenothiazine donor to furnish XW53 with the aim to further improve the anti-aggregation character and the solubility, and thus the Voc was improved to 674 mV, and a higher efficiency of 7.9% was achieved for XW53. Upon cosensitization with PT-C6, the Voc and Jsc were synergistically enhanced to 727 mV and 18.67 mA cm-2, respectively. As a result, a high efficiency of 9.6% was successfully achieved for the cosensitization system of XW53 + PT-C6. These results provide an effective novel strategy for designing efficient porphyrin dyes by introducing multiple benzyloxy groups to the meso-phenyl groups.
关键词： cosensitization,porphyrins,dye aggregation,dye-sensitized solar cells,wrapped structures
更新于2025-09-12 10:27:22
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π-Extended <i>cis</i> -Configured Unsymmetrical Squaraine Dyes for Dye-sensitized Solar Cells: Panchromatic Response
摘要： Light absorbing sensitizer is the heart of the third generation photovoltaic technologies such as dye-sensitized solar cells (DSSC). Despite possessing large extinction coefficients for the metal free organic dyes, the light harvesting efficiency is limited with the narrow absorption profile in either visible or NIR regions of the solar spectrum. Though monolayer formation of organic sensitizers on semiconducting metal oxide surface leads to dye-dye interaction that leads to broadening the absorption profile, the contribution of aggregated state to the power conversion process is found out to be poor. Here we have engineered far red active π-extended cis-configured unsymmetrical squaraine dyes with carboxylic acid and cycnoacetic acid as anchoring groups with controlled aggregation and panchromatic light absorption by including the steric and electronic factors. The presence of sp3-C (out of plane) and N-alkyl (in plane) groups played an important role in modulating the assembly the dyes on the TiO2 electrode, cis-squaraine unit helps to extend the conjugation in the NIR region besides enhancing the visible transition and the incident photon-to-current conversion efficiency (IPCE) profile showed the importance of anchoring groups for the panchromatic response. Dye PSQ10 showed solar-to-electric conversion with an onset of 850 nm with the device performance of 7.0% (Voc = 0.581 V, Jsc = 17.06 mA/cm2, FF = 70 %).
关键词： cis-Squaraine dyes,panchromatic response,dye-sensitized solar cells,extended far-red absorption,dye aggregation
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Binary Semiconductor Metal Oxide as Photoanodes
摘要： As both natural and synthetic metal oxide semiconductors (MOSs) have diverse applications and the properties of MOS can be tailored in many ways, viz., varied choice of morphologies, introducing oxygen vacancies, doping. In photovoltaics, MOSs serve as a scaffold layer for loading dyes in dye-sensitized solar cells (DSSCs) and organic–inorganic hybrid perovskites in perovskite solar cells (PSCs), as well as electron and hole transport layers in DSSCs and organic solar cells (OSCs). The function of scaffold in DSSCs is to facilitate charge separation and charge transport, whereas that of the transport layers is to conduct one type of charge carrier block to the other type. Therefore, tailoring their properties is inevitable to develop high-performing photovoltaic devices using them. On the other hand, the electrochemical properties of the MOS such as band edge energies determine their success as photocatalysts [1].
关键词： metal oxide semiconductors,perovskite solar cells,photovoltaics,charge transport,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Investigation of Low Temperature Processed Titanium Dioxide (TiO2) Films for Printed Dye Sensitized Solar Cells (DSSCs) for Large Area Flexible Applications
摘要： This paper reports a systematic study of the effect of nano-crystalline titanium dioxide (TiO2) formulations and annealing temperature conditions on the performance of dye sensitized solar cells (DSSCs) realized on fluorine tin oxide (FTO) glass substrates. DSSC fabrication is restricted to high temperature (>150 oC) process-compatible materials by the nano-crystalline process of the TiO2. DSSCs benefit from the use of lower cost materials and offer higher efficiency than organic solar cells but high processing temperatures limit their application on, for example, textile substrates. The aim of this study is to develop and optimize a low temperature processable TiO2 formulation suitable for both screen printing and spray coating. The results from this paper can be applied in future fabrication processes on flexible plastic and fabric substrates. The challenge of this research work is to achieve the smooth deposition and processing at 150 oC of TiO2 layers on glass substrates. We report a maximum DSSC efficiency of 4.3 % achieved by screen printing and 2.5 % achieved by spray coating on a glass substrate using the new low temperature process.
关键词： low temperature TiO2,Dye sensitized solar cells,flexibe solar cells
更新于2025-09-12 10:27:22
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Mono- and bi-cyanoacrylic acid substituted phenothiazine based sensitizers for dye sensitized solar cells
摘要： Phenothiazine and cyanoacrylic acid moiety based sensitizers were synthesized for dye sensitized solar cell application. Absorption and electrochemical properties of the sensitizers having mono- and bi-substituted cyanoacrylic acids were studied. The mono-cyanoacrylic acid substituted phenothiazine sensitizer has more light harvesting ability due to its high molar extinction coefficient. The photovoltaic performance of mono-cyanoacrylic acid substituted phenothiazine sensitizer was slightly greater compared to the bi-cyanoacrylic acid substituted phenothiazine sensitizer which was attributed to the effect of anchoring groups in the sensitizer.
关键词： Solar energy materials,Spectroscopy,Anchoring group,Dye sensitized solar cells,Phenothiazine
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Dye‐Sensitized Solar Cells: History, Components, Configuration, and Working Principle
摘要： The ever-growing human population requires the consumption of energy in various forms, and therefore researchers in energy field focus on energy harvesting from various sources. The nonrenewable energy sources such as fossil fuels are running out, which cannot be replenished in our life time. The nonrenewable energy sources are carbon-based fossil fuels such as coal, petroleum, and natural gas that emits greenhouse gases (for example carbon dioxide) that cause global warming, a serious threat to the world and mankind. At present, worldwide around three-fourth of the electricity is obtained from the nonrenewable sources that cannot be reused or recycled [1]. Many countries such as Japan, China, France, Ukraine, and India depend on nuclear power stations for the production of electricity and also they are facing several harmful issues from these power plants that lead to environmental pollution [2]. Therefore, the focus of scientists mainly rely on the renewable energy-based energy conversion devices. Solar, wind, hydroelectric, biomass, and geothermal are some of the examples of renewable energy resources available in our earth. Of these, solar energy is an important source of renewable energy, which is available throughout a day all over the year, basically inexhaustible in nature. In case of solar energy, radiation obtained from the sunlight is capable of producing heat and light, causes photochemical reactions, and generates electricity. As the electricity becomes a first and foremost basic need for the mankind, this impressive energy source can be utilized for the conversion of solar to electrical energy using solar cell technology. The strength of solar energy is magnanimous as it provides us about 10 000 times more energy that is higher than the world’s daily need of energy consumption [1]. The earth receives such a huge amount of energy every day, we are fortunate to harness it using suitable solar cell technologies. Regrettably, though solar energy is free of cost, the highly expensive technologies required for its conversion and storage which limit the technology to reach the wider community.
关键词： Dye-Sensitized Solar Cells,photoanode,TiO2,solar energy,dyes,photovoltaic effect,DSSCs,counter electrode,renewable energy,electrolytes
更新于2025-09-12 10:27:22
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Highly Crystallized C-Doped Nickel Oxide Nanoparticles for p-Type Dye-Sensitized Solar Cells with Record Open-Circuit Voltage Breaking 0.5 V
摘要： In this work, unique carbon-doped NiO nanostructure (denoted as C/NiO) was synthesized via a facile precipitation/reduction reaction, followed by a subsequent oxidation process. The successful introduction of carbon in NiO gave rise to multiple tailing of the physical and electronic characteristics, including morphology, crystallinity, and conductivity, and valence band edge position. The carbon-doped NiO-fabricated dye sensitized solar cells actively generated an unrivalled VOC of 0.50 V and also a significantly increased short-circuit current densities (JSC, 0.202 mA cm-2), leading to an overall efficiency of 0.053%. The improved of photovoltaic performance could be mainly attributed to the significantly enhanced charge transport property and regarded charge recombination occurred at the NiO/electrolyte interface. This work provides an extremely simple and effective strategy for incorporating nonmetal elements in semiconductor oxides with remarkably improved photovoltaic performance.
关键词： charge transport,carbon-doped NiO,dye-sensitized solar cells,photovoltaic performance,valence band edge
更新于2025-09-12 10:27:22
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Synthesis of Anatase (Core)/Rutile (Shell) Nanostructured TiO <sub/>2</sub> Thin Films by Magnetron Sputtering Methods for Dye-Sensitized Solar Cell Applications
摘要： Currently, anatase/rutile core/shell structures are accepted as highly efficient building blocks for TiO2-based catalysts or photo-electrodes used in dye-sensitized solar cells (DSSCs). It is understood that a thin layer of rutile covering the core anatase pillar would improve the performance of DSSCs by retarding the charge recombination at the semiconductor/sensitizer/electrolyte interfaces. In this work, we report on the synthesis of core/shell nanostructured TiO2 thin films using reactive magnetron sputtering at a glancing angle with different power applying modes: well-separated pillars of pure anatase were synthesized using the DC mode, and then, high-pulse peak power was applied to the Ti target (high power impulse magnetron sputtering – HiPIMS) resulting in the covering of the anatase columns with a thin layer of rutile. The latter technique is well-known to increase the energy load during the growth of the film which is a key parameter to successfully obtain the TiO2 phase normally only achieved at high temperature, i.e. rutile. The peak current, the frequency and the pulse width were optimized in order to obtain the desired crystalline structure and thickness of the rutile top layer. Scanning Electron Microscopy (SEM) cross-section views of the synthesized films clearly show that the pillar-like structures are not affected by the energetic species striking the surface during the HiPIMS process. Grazing Incidence X-Ray Diffraction (GIXRD) suggests the presence of both anatase and rutile phases in the films. Further characterization of the anatase/rutile core/shell interface by electron transmission techniques such as Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS) mapping confirm the hypothesis and reveal that the anatase pillars are partly covered by a rutile crust.
关键词： EELS,Dye-Sensitized Solar Cells,TEM,TiO2,GLAD,Reactive Magnetron Sputtering,core/shell nanostructures,HiPIMS
更新于2025-09-12 10:27:22