Elena Guillén

Bio: Elena Guillén is an academic researcher from Pablo de Olavide University. The author has contributed to research in topics: Dye-sensitized solar cell & Solar cell. The author has an hindex of 17, co-authored 28 publications receiving 1714 citations.

ZnO-Based Dye-Sensitized Solar Cells

Abstract: ZnO was one of the first metal oxides used in dye-sensitized solar cells (DSCs). It exhibits a unique combination of potentially interesting properties such as high bulk electron mobility and probably the richest variety of nanostructures based on a very wide range of synthesis routes. However, in spite of the huge amount of literature produced in the past few years, the reported efficiencies of ZnO-based solar cells are still far from their TiO2 counterparts. The origin of this striking difference in performance is analyzed and discussed with the perspective of future applications of ZnO in dye-sensitized solar cells and related devices. In this regard, a change of focus of the current research on ZnO-based DSCs (from morphology to surface control) is suggested.

Metal free sensitizer and catalyst for dye sensitized solar cells

Abstract: The carbon neutral process for energy conversion is of utmost importance, in this context photovoltaics, especially dye sensitized solar cells (DSSCs) are a viable alternative. Few terawatts of carbon free renewable energy can be produced by DSSCs. However the judicious use of platinum group free metals may further enhance the limit of energy production by making it further cost effective. In this context a metal free sensitizer and electrocatalyst related to DSSCs are reviewed for their merits. The current state-of-the-art sensitizer as well as carbon based materials for its chemistry and photovoltaic characterization are discussed. The present article combines recent progress and its emerging behavior from our laboratories and from other groups working on this perennial topic.

Elucidating Transport-Recombination Mechanisms in Perovskite Solar Cells by Small-Perturbation Techniques

Abstract: Solar cells using perovskite as semiconducting pigment have recently attracted a surge of interest owing to their remarkable solar-to-electric conversion efficiencies and ease of processing. In this direction various device architectures and materials have been employed, and attempts were made to elucidate the underlying working principles. However, factors governing the performance of perovskite devices are still obscure. For instance, the interpretation of electrochemical impedance spectroscopy (EIS) is not straightforward, and the complexity of the equivalent circuits hinders the identification of transport and recombination mechanisms in devices, especially those that determine the performance of the device. Here in we carried out a comprehensive and complementary characterization of perovskite solar cells by using an array of small-perturbation techniques: EIS and intensity-modulated photocurrent and photovoltage spectroscopy (IMPS/IMVS). The employment of IMPS allowed us to identify two transport ti...

Electron Transport and Recombination in ZnO-Based Dye-Sensitized Solar Cells

Abstract: The photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) has been studied for three different configurations involving two dyes and two types of electrolytes with the iodide/iodine as redox mediator: ZnO/N719/organic solvent electrolyte (C1), ZnO/D149/organic solvent electrolyte (C2), and ZnO/N719/ionic liquid electrolyte (C3). The DSCs were characterized by measuring current–voltage curves and photovoltage as a function of light intensity and by electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS), intensity-modulated photovoltage spectroscopy (IMVS), and open circuit photovoltage decay (OCVD). The results demonstrate the good light harvesting properties of the D149 dye and highlight the photovoltage limitation of the solvent-free (ionic liquid) electrolyte. The intensity dependence of the photovoltage and the OCVD, EIS, and IMVS results provide evidence of the nonlinear character of the recombination kinetics. It has been found that by com...

Photovoltaic performance of nanostructured zinc oxide sensitised with xanthene dyes

Abstract: The photovoltaic properties of nanostructured ZnO electrodes prepared from commercially available ZnO nanoparticles (Degussa) and sensitised with xanthene dyes are explored. We have used Eosin Y, Eosin B and Mercurochrome and compared their performance to that of the more common N719 dye. We observe that these dyes efficiently sensitise commercial ZnO nanopowder and yield efficiencies that are very competitive with respect to those provided by N719. Local photocurrent and transmittance measurements as a function of the wavelength confirm the good performance of the xanthene dyes in the absorption maxima. We have prepared polymer-sealed cells and measured the short-circuit current of the devices under continuous illumination at 200 mW/cm2 corresponding to twice the standard solar light intensity. The organic dyes show very good stability properties under these conditions. The combination of a versatile metal oxide such as ZnO and inexpensive organic dyes should be considered as a promising alternative in the field of dye-sensitised solar cells.

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance

Abstract: All of the cations currently used in perovskite solar cells abide by the tolerance factor for incorporation into the lattice. We show that the small and oxidation-stable rubidium cation (Rb + ) can be embedded into a “cation cascade” to create perovskite materials with excellent material properties. We achieved stabilized efficiencies of up to 21.6% (average value, 20.2%) on small areas (and a stabilized 19.0% on a cell 0.5 square centimeters in area) as well as an electroluminescence of 3.8%. The open-circuit voltage of 1.24 volts at a band gap of 1.63 electron volts leads to a loss in potential of 0.39 volts, versus 0.4 volts for commercial silicon cells. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full illumination and maximum power point tracking.

Perovskite as Light Harvester: A Game Changer in Photovoltaics

Abstract: It is not often that the scientific community is blessed with a material, which brings enormous hopes and receives special attention. When it does, it expands at a rapid pace and its every dimension creates curiosity. One such material is perovskite, which has triggered the development of new device architectures in energy conversion. Perovskites are of great interest in photovoltaic devices due to their panchromatic light absorption and ambipolar behavior. Power conversion efficiencies have been doubled in less than a year and over 15% is being now measured in labs. Every digit increment in efficiency is being celebrated widely in the scientific community and is being discussed in industry. Here we provide a summary on the use of perovskite for inexpensive solar cells fabrication. It will not be unrealistic to speculate that one day perovskite-based solar cells can match the capability and capacity of existing technologies.