Henrik Lindström

A 5% efficient photoelectrochemical solar cell based on nanostructured ZnO electrodes

Nanoporous ZnO electrodes, dye-sensitized with a ruthenium bipyridyl complex, were used as photoanodes in photoelectrochemical solar cells. By improving the interfacial contact between dyes and ZnO particles in the film, overall solar-to-electric energy conversion efficiencies of up to 5% were obtained. The solar cell performance was studied as a function of film thickness, residence time of the electrodes in the dye solution, electrolyte composition and light intensity.

A new method to make dye-sensitized nanocrystalline solar cells at room temperature

This paper describes a new method for manufacturing a nanostructured porous layer of a semiconductor material at room temperature. The porous layer is pressed on a conducting glass or plastic substrate for use in a dye-sensitized nanocrystalline solar cell. The method compresses the particle layer to form a mechanically stable, electrically conducting, porous nanostructured film. Overall, solar to electric conversion efficiencies of up to 5.2% at 0.1 sun using plastic substrates have been obtained.

Photoelectrochemical studies of colloidal TiO2 films: The effect of oxygen studied by photocurrent transients

The effect of oxygen in nanocryst. colloidal TiO2 film photoelectrodes were studied by optically induced photocurrent transient measurements. O2 played an important role in the recombination of electrons and holes. Some effects esp. assocd. with the nanoporous morphol. of these photoelectrodes are discussed.

Verification of High Efficiencies for the Grätzel Cell : A 7% Efficient Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films.

Verification of High Efficiencies for the Gratzel Cell : A 7% Efficient Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films.

A new method for manufacturing nanostructured electrodes on glass substrates

The present paper describes a new method for manufacturing a nanostructured porous layer of a semiconductor material on a conducting plastic substrate for use in an electrochemical or photoelectrochemical cell. The method involves the deposition of a layer of semiconductor particles on conducting plastic and the compression of the particle layer to form a mechanically stable, electrically conducting, porous nanostructured film at room temperature. Photoelectrochemical characteristics of the resulting nanostructured films are presented showing, for example, overall solar to electric conversion efficiencies of up to 4.9% (0.1 sun). The potential use of the new manufacturing method in future applications of nanostructured electrodes is discussed.

Charge transport properties in the nanostructured ZnO thin film electrode – electrolyte system studied with time resolved photocurrents

The charge transport in nanoporous ZnO was studied by laser flash induced photocurrent transients. The results are discussed using a diffusion model and compared with previous results on TiO2. The charge transport was highly dependent on the potential giving apparent diffusion coeffs. for the electron ranging from 1×10-4 to 1×10-6 cm2/s with an applied bias of +100 and +300 mV vs. Ag/AgCl in ethanol, resp. The electrolyte was 0.5 M LiClO4 in ethanol. The potential dependence was much more pronounced for ZnO than for TiO2. The charge transport was also dependent on the electrolyte giving a linear dependence between the cond. of the electrolyte and the apparent electronic diffusion coeff. The dependence of the light intensity was also studied. Intensity-dependent losses were obsd.

Photocurrent Losses in Nanocrystalline/Nanoporous TiO2 Electrodes Due to Electrochemically Active Species in the Electrolyte

The photoelectrochemical properties of nanostructured highly porous TiO2 electrodes with different thicknesses (2 to 38 mu m) were investigated. The effects of electron accepters, such as oxygen and iodine, in the electrolyte were studied by action spectr

Electronic structure of electrochemically Li-inserted TiO2 studied with synchrotron radiation electron spectroscopies

The electronic properties of TiO2 and electrochemically Li-inserted TiO2 have been studied using synchrotron radiation photoelectron spectroscopy and x-ray absorption spectroscopy (XAS) in conjunction with resonant photoelectron spectroscopy. Core level (Ti 2p) and valence level spectra show the presence of Ti3+ states in LixTiO2. The x values determined from core level peak intensities were found to be directly correlated to the inserted amount of Li+ determined electrochemically. The x-dependent width of the Ti 2p peaks is consistent with a two-phase regime at intermediate x values. Resonant photoelectron spectroscopy at the Ti 2p edge was performed for TiO2 and Li0.5TiO2 to delineate the Ti4+ and Ti3+ contributions to the XAS spectrum.

Redox properties of nanoporous TiO2 (anatase) surface modified with phosphotungstic acid

Nanostructured anatase TiO2 electrodes surface modified with inorg. metal oxide clusters, i.e., phosphotungstic acid (PWA), was studied by XPS and spectroelectrochem. The surface modifiers were electroactive and could be addressed reversibly by changing the applied bias. The formation of new states in the electronic structure of TiO2 and the PWA was monitored by XPS using a novel prepn. technique. The coloration efficiency of the deposit was about 20 cm2/C. Prolonged electrochem. cycling degraded the elec. contact between the PWA and the TiO2 surface.

Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semi-empirical calculations

Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semi-empirical calculations