A. Hagfeldt | Ecole Polytechnique Federale de Lausanne (original) (raw)

Papers by A. Hagfeldt

Coordination Chemistry Reviews, 2004

Comprehensive Renewable Energy, 2012

Journal of Physical Chemistry, 1993

Thin Solid Films, 2008

A small organic sensitizer, the polyene-diphenylaniline dye D5, was compared with the standard se... more A small organic sensitizer, the polyene-diphenylaniline dye D5, was compared with the standard sensitizer N719 (Ru (dcbpy) 2 (NCS) 2) in a dye-sensitized solar cell investigation. In solar cells with relatively thin layers of mesoporous TiO2 (< 3 μm) D5 outperformed ...

The Journal of Physical Chemistry C, 2007

Nanocrystalline particles of ZnO and TiO 2 of approximately equal size (∼15 nm) were used to prep... more Nanocrystalline particles of ZnO and TiO 2 of approximately equal size (∼15 nm) were used to prepare mesoporous electrodes for dye-sensitized solar cells. Electron transport in the solar cells was studied using intensity-modulated photocurrent spectroscopy and revealed very similar results for ZnO and TiO 2 . Apparent activation energies for electron transport in nanostructured ZnO of e0.1 eV were calculated from the temperature dependence of transport times under short-circuit conditions. The lifetime of electrons in the nanostructured semiconductors was evaluated from open-circuit voltage decay and intensity-modulated photovoltage spectroscopy. Significantly longer lifetimes were obtained with ZnO. Despite the reduced recombination, ZnO-based solar cells performed worse than TiO 2 cells, which was attributed to a lower electron injection efficiency from excited dye molecules and/or a lower dye regeneration efficiency. The internal voltage in the nanostructured ZnO film under short-circuit conditions was about 0.23 V lower than the opencircuit potential at the same light intensity. Results may be explained using a multiple trapping model, but as electrons are usually only shallowly trapped in ZnO, an alternative view is presented. If there is significant doping of the ZnO, resulting band bending in the nanocrystals will form energy barriers for electron transport and recombination that can explain the observed properties.

Solar Energy Materials and Solar Cells, 2006

In this paper, we present a simulation platform designed to study coupled charge transport in dye... more In this paper, we present a simulation platform designed to study coupled charge transport in dyesensitized solar cell (DSC) devices. The platform, SLICE, is used to study the influence of ions in the electrolyte on electron transport in the nanoporous medium. The simulations indicate that both cationic and anionic properties should be considered when modelling DSCs and similar systems. Additionally, it was found that the effective permittivity coefficient, e, has no influence on the electron transport when the ionic concentration is sufficiently high due to the strong coupling between the respective charged species. r

Journal of The Electrochemical Society, 1994

Forward biasing of transparent nanocrystalline (anatase) films in lithium ion‐containing organic ... more Forward biasing of transparent nanocrystalline (anatase) films in lithium ion‐containing organic electrolytes leads to rapid andreversible coloration due to electron accumulation and Li intercalation in the anatase lattice. Absorption of&gt; 90% light throughout the ...

Journal of The Electrochemical Society, 2000

is at present intensively studied. Photoelectrochemical systems based on TiO 2 are the most exten... more is at present intensively studied. Photoelectrochemical systems based on TiO 2 are the most extensively studied and at present also the most promising. Hematite (␣-Fe 2 O 3 ), the thermodynamic stable crystallographic phase of iron(III) oxide with a bandgap of 2.2 eV, has been studied, for example, as a gas sensor, 5 photoanode for photo-oxidation of water, 6,7 and for photocatalytic oxidation. 8 The quantum yield reached is very promising, and its nontoxicity, low cost, and relatively good stability are definitely very attractive features for these applications.

Advanced Materials, 2004

30 mL). A constant current of typically 1 lA was applied between two platinum electrodes immersed... more 30 mL). A constant current of typically 1 lA was applied between two platinum electrodes immersed in the solution in two compartments, separated by a glass frit.