The Application of ZnO Nanoparticles Containing Polyoxometalates in Dye-Sensitized Solar Cells

Polyoxometalates in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are the third generation of photovoltaic cells developed by Grätzel and O'Regan. They have the characteristics of low cost, simple manufacturing process, tunable optical properties, and higher photoelectric conversion efficiency (PCE). With an ever increasing energy crisis, there is an urgent need to develop highly efficient, environmentally benign, and energy-saving cell materials. Polyoxometalates (POMs), a kind of molecular inorganic quasi-semiconductor, are promising candidates for use in different parts of DSSCs due to their excellent photosensitivity, redox, and catalytic properties, as well as their relative stability. Following a brief introduction to the development of DSSCs and the potential virtues of POMs in DSSCs, we attempt to make some generalizations about the energy level regulation of POMs that is the underlying theoretical basis for their application in DSSCs, and then we summarize the research progress of POMs in DSSCs in recent years. This is organized in terms of the properties of POMs, namely, electron acceptor, photosensitivity, redox and catalysis, based on the accumulation of our research into POMs over many years. Meanwhile, in view of the fact that the properties of POMs depend primarily on their electronic structural diversity, we keep this point in mind throughout the article with a view to revealing their structure-property relationships. Finally we provide a short summary and remarks on the future outlook. This review may be of interest to synthetic chemists devoted to designing POMs with specific structures, and researchers engaged in the extension of POMs to photoelectric materials.

A Strategy to Enhance the Efficiency of Quantum Dot-Sensitized Solar Cells by Decreasing Electron Recombination with Polyoxometalate/TiO2 as the Electronic Interface Layer

Electron recombination occurring at the TiO₂ /quantum dot sensitizer/electrolyte interface is the key reason for hindering further efficiency improvements to quantum dot sensitized solar cells (QDSCs). Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device owing to its excellent oxidation/reduction properties and thermostability. A POM/TiO₂ electronic interface layer prepared by a simple layer-by-layer self-assembly method was added between fluorine-doped tin oxide (FTO) and mesoporous TiO₂ in the photoanode of QDSCs, and the effect on the photovoltaic performance was systematically investigated. Photovoltaic experimental results and the electron transmission mechanism show that the POM/TiO₂ electronic interface layer in the QDSCs can clearly suppress electron recombination, increase the electron lifetime, and result in smoother electron transmission. In summary, the best conversion efficiency of QDSCs with POM/TiO₂ electronic interface layers increases to 8.02 %, which is an improvement of 25.1 % compared with QDSCs without POM/TiO₂ . This work first builds an electron-transfer bridge between FTO and the quantum dot sensitizer and paves the way for further improved efficiency of QDSCs.

Increasing p-type dye sensitised solar cell photovoltages using polyoxometalates

Lindqvist polyoxometalates increase p-DSSC V_OC by up to 140%, through a combination of retarded recombination, valence band shift and screening.

Efficient dye-sensitized solar cell with a pure thin film of a hybrid polyoxometalate covalently attached organic dye as a working electrode in a cobalt redox mediator system

A Keggin-type hybrid polyoxometalate is used as a pure semiconductor thin film in the working electrode of a dye-sensitized solar cell fabricated with a D35 organic dye and a cobalt redox mediator system, giving a maximum IPCE of about 91% .

Thermoregulated polyoxometalate-based ionic-liquid gel electrolytes

Thermoregulated POM-type ionic liquid gels show reversible phase transformation, increasing conductivities. And W-containing compounds have higher conductivity than the Mo-containing one, like the Dawson-type one compared with the Keggin-type one.

A novel carboxyethyltin functionalized sandwich-type germanotungstate: synthesis, crystal structure, photosensitivity, and application in dye-sensitized solar cells

A novel sandwich-type germanotungstate [C(NH2)3]10[Mn2{Sn(CH2)2COOH}2(B-α-GeW9O34)2]·8H2O (1) represents the first single crystalline polyoxometalate (POM) functionalized by open chain carboxyethyltin, which was designed and synthesized in aqueous solution and applied to a dye-sensitized solar cell (DSSC) for the first time. Its photosensitivity was explored through a fluorescence spectrum (FL), surface photovoltage spectrum (SPV), electrochemical method, and solid diffuse spectrum. 1 displays the primary features of sensitizers in DSSCs, and the efficiency of the solar cell is 0.22%. Delightedly, when 1 was employed to assemble a cosensitized solar cell configuration by preparing a 1-doped TiO2 electrode and additionally adsorbing N719 dyes, a considerably improved efficiency was achieved through increasing spectral absorption and accelerating electron transport, which is 19.4% higher than that of single N719 sensitization. This result opens up a new way to position different dyes on a single TiO2 film for cosensitization.