Electrolytes in Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSCs) are well researched globally due to their potential as low-cost photovoltaic (PV) devices especially suited for building and automobile integrated PV (BIPV, AIPV) and portable or indoor light harvesting applications. Since 1991, large monetary and intellectual investments have been made to develop DSCs into deployable technologies, creating a wealth of knowledge about nano-interfaces and devices through an increasing number of research reports. In response to these investments, the dawn of the new millennium witnessed the emergence of a corporate sector of DSC development. Advances in their design, their incorporation on flexible substrates, the development of solid state modules, their enhanced stability in outdoor environments, and their scalable fabrication tools and techniques have allowed DSCs to move from the laboratory to real-life applications. Although photoconversion efficiencies are not on a par with commercially available CIGS or single crystalline silicon solar cells, they possess many features that compel the further development of DSC modules, including transparency, light weight, flexibility, conformability, workability under low-light conditions, and easy integration in buildings as solar windows. In fact, DSC panels have been shown to deliver even more electricity than their silicon and thin film counterparts of similar power ratings when exposed to low light operating conditions due to their workability in such conditions; thus, they are potential market leaders in BIPV and indoor light harvesting photovoltaic technology. However, large area dye-solar modules lack in performance compared to their laboratory scale devices and also suffer from long term stability issues. Herein, we discuss the main factors behind their inferior photovoltaic performance and identify possible opportunities for the design of more efficient DSC modules.

A perspective on the production of dye-sensitized solar modules

Surfactant-free mixed-metal hydroxide water oxidation nanocatalysts were synthesized by pulsed-laser ablation in liquids. In a series of [Ni-Fe]-layered double hydroxides with intercalated nitrate and water, [Ni1–xFex(OH)2](NO3)y(OH)x−y·nH2O, higher activity was observed as the amount of Fe decreased to 22%. Addition of Ti4+ and La3+ ions further enhanced electrocatalysis, with a lowest overpotential of 260 mV at 10 mA cm–2. Electrocatalytic water oxidation activity increased with the relative proportion of a 405.1 eV N 1s (XPS binding energy) species in the nanosheets.

Highly active mixed-metal nanosheet water oxidation catalysts made by pulsed-laser ablation in liquids.

Two-dimensional layered double hydroxides (LDHs) are currently a topic of significant interest due to their extraordinary physiochemical properties. LDHs are potentially useful in a wide range of applications, particularly in environmental, energy, catalysis, and biomaterials related fields. Despite the unique intrinsic properties of LDHs, various functionalization strategies have been applied to LDHs that yield even more exciting performance opportunities, offering guides to design novel functional nanomaterials. In this review, we address how these strategies can improve the various properties of LDHs. We provide an overview of the functionalizing strategies of intercalation, surface modification, hybridization, layered compositions regulation, size and morphology control, and defect creation. These strategies contribute significantly to the enhancement of the performance of LDHs, across a diverse range of areas such as adsorptive, catalytic, electronic, electrochemical, and optical. As a result, functionalized LDHs exhibit great potential in a wide range of applications in the environmental and energy domains. We have comprehensively highlighted their emerging potential in the environmental, energy, catalysis, and biomaterials related fields, including heavy metal removal, radionuclide capture, organic contaminants purification, oil pollution elimination, hydrogen generation, supercapacitors, batteries, solar cells, catalysis, and biomaterial fabrication.

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Functionalized layered double hydroxides for innovative applications

Temperature is probably the most important outdoor variable that affects the photovoltaic performance of the dye sensitized solar cells (DSSCs) Overall stability of DSSCs depends on the properties of charge mediator (electrolyte) between photoanode and counter electrode The liquid electrolytes show high power efficiency owing to their high dielectric constants to dissolve many ionic salts and additives However, they may limit the outdoor applications in high temperature region, due to their low boiling points (highly volatile) The objective of this study is to highlight the prospects of solid state dye-sensitized solar cells and its benefit in higher temperature environment The current review is comprised of four sections In the first section (introduction), the effect of temperature on the conventional and solid-sate DSSCs is briefly described In the second section, the mechanism of solid-state DSSCs is explained Third section we covered recent advances in ss-DSSCs in detail Finally, the scope of DSSCs in high temperature environment critically analyzed in section four

Effect of temperature on the photovoltaic performance and stability of solid-state dye-sensitized solar cells: A review

In recent research in clean energy applications, clay has gained significant interest, especially as a gelator in dye-sensitized solar cells (DSSCs), for its capability to resolve the leakage issue of liquid electrolyte. In this paper, anionic hydrotalcite is utilized as a gelator to assist the formation of gel electrolyte in DSSCs. Three types of hydrotalcite with exchangeable anions, viz. NO3− (CL-N), CO32− (CL-C) and SO42− (CL-S), were synthesized with similar morphologies via the co-precipitation method. It is observed that the gel formation of hydrotalcite strongly depends on the exchangeable anions present in the hydrotalcite. The objective of this work is to understand the effect of hydrotalcite anions on the photovoltage and the photocurrent in the gel electrolyte through electrochemical analysis. With increasing ion affinity, the Voc increases. This is attributed to Li+ intercalation with hydrotalcite compound resulting in the elevation of the conduction band of TiO2. With increasing ion affinity, the Jsc decreases. This is attributed to the decreasing diffusion coefficient of triiodide and the increasing difficulty in the injection process. For anions with low ion affinity in hydrotalcite, the diffusion of the redox couple is not significantly affected by the high viscosity of the gel. Furthermore, the study indicates that proper selection of hydrotalcite compounds not only produces a quasi-solid gel electrolyte, but also increases the efficiency of the solar cells: the device performance was improved from 7.8% (liquid electrolyte) to 8.4% (hydrotalcite gel electrolyte).

Ran Deng

Papers

Investigation of the role of anions in hydrotalcite for quasi-solid state dye-sensitized solar cells application