Toby Meyer

ABSTRACT The efficiency of photocatalytic materials can be investigated by several direct and indirect methods. In this study, photocatalytic materials are prepared from TiO2 Solaronix™ nano-suspension by dip- and spin-coating methods. The photocatalytic activity of coatings is then assessed for several deposition and analysis parameters. An on-line indirect measure method is presented. This method is based on stearic acid degradation and allows the assessment of non-transparent photocatalytic films and displays a high sensitivity. The influences of nano-powder diameter and sintering temperature on film photocatalytic activity are discussed. The reproducibility of the assessment method is presented, and its dependency toward temperature and humidity is measured. Titanium dioxide films prepared from nano-powders are compared to similar coatings in order to illustrate the subject.

Precursor pastes for Cu(In,Ga)Se2 (CIGS) were deposited by a simple and low cost deposition method. Selenization is performed using non-toxic roots to convert the precursor into a ClGS layer. Scanning electron microscopy and energy dispersive X-ray spectroscopy show homogenous films in composition, thickness and morphology, comparable to vacuum evaporated ClGS films. X-ray diffraction results indicate the formation of single phase ClGS. Preliminary processing of solar cells with CdS/ZnO/ZnO:Al layers yielded cell efficiencies of 4%.

A simple process for the deposition of Cu (In, Ga) Se2 (CIGS) absorber layers is described. A low-cost CIGS precursor paste deposited by simple and fast doctor blade technique is subsequently selenized under selenium vapour in a quartz tube at 10 mbar (10 min at 550 ...

Seven unsymmetrical heptamethine dyes with carboxylic acid functionality were synthesized and characterized. These near-infrared dyes exhibit outstanding photophysical properties depending on their heterocyclic moieties and molecular structure. As proof of principle, the dyes were used as photosensitizers in dye-sensitized solar cells. Using the most promising dye, an overall conversion efficiency of 1.22% and an almost colorless solar cell were achieved.

Luminescent solar concentrators (LSCs) generally consist of transparent polymer sheets doped with luminescent species. Incident sunlight is absorbed by the luminescent species and emitted with high quantum efficiency, such that emitted light is trapped in the sheet and travels to the edges where it can be collected by solar cells. LSCs offer potentially lower cost per Wp. This paper reviews results mainly obtained within the framework of the Full-spectrum project. Two modeling approaches are presented, i.e., a thermodynamic and a ray-trace one, as well as experimental results, with a focus on LSC stability.

ABSTRACT a b s t r a c t The use of a synthetic saponite-clay with different morphological features is proposed in this work as additive for DSSC solar cells electrolyte. The dilution of the synthesis gel allowed to decrease the saponite particle size from ca. 200 nm to ca. 50 nm and to obtain samples with different lamellae organization. The influence of these parameters on solar cell performances have been tested by dispersing 5 wt% of the clay in Z-946 liquid electrolyte and using the dispersion as non-liquid electrolyte. The stability of saponite dispersions in methoxyproprionitrile solvent has been studied by Dynamic Light Scattering (DLS). The electrochemical characterization showed that the addition of the saponite sample with the largest particles does not influence the solar cell efficiency, whereas the use of electrolyte having saponite suspension with the smallest particle size led to an increase of solar cell efficiencies of 8% with respect to the reference cell. Finally, tests devoted to investigate the stability over the time of DSSC prepared by using quasi-solid saponite-based electrolytes have been carried out. & 2013 Published by Elsevier B.V.

ABSTRACT A nanosized layered double hydroxide (n-LDH) was intercalated with growing amount of iodine and the resulting materials used as additives for the preparation of quasi-solid electrolytes for dye-sensitized solar cells (DSSC). The influence of the amount of iodine on solar cell performances was tested by dispersing 5 wt% of intercalated LDH in a methoxypropionitrile-based liquid electrolyte and using the obtained dispersion for DSSC assembly. The electrochemical characterization of the devices showed that the addition of increasing amount of iodine intercalated LDH has a positive effect on solar cell photoenergy conversion. In addition, time stability of devices prepared with non-liquid electrolyte were taken into consideration.

Advances in nanoparticle technology led to powerful low-cost thin film techniques. Together with the established selenization method, these techniques open new possibilities for low-cost solar cell production that does not require expensive vacuum deposition systems. ...

ABSTRACT The efficiency of photocatalytic materials can be investigated by several direct and indirect methods. In this study, photocatalytic materials are prepared from TiO2 Solaronix™ nano-suspension by dip- and spin-coating methods. The photocatalytic activity of coatings is then assessed for several deposition and analysis parameters. An on-line indirect measure method is presented. This method is based on stearic acid degradation and allows the assessment of non-transparent photocatalytic films and displays a high sensitivity. The influences of nano-powder diameter and sintering temperature on film photocatalytic activity are discussed. The reproducibility of the assessment method is presented, and its dependency toward temperature and humidity is measured. Titanium dioxide films prepared from nano-powders are compared to similar coatings in order to illustrate the subject.

Latest results show an 8.2 % efficiency obtained with industrially viable materials and processes. Stability in outdoors and simulated conditions are also presented. An elegant assembly technique has been developed for large area dye solar cells intended for outdoors applications. Solid-state dye solar cells show an efficiency up to 4 % in low light conditions, making them ready for indoor applications.

For the first time, large area nanocrystalline titanium oxide based Dye Solar Cell modules with a size up to 45 x 45 cm have been manufactured with industrial methods and materials, opening a way to real products for selected markets. The electrical performances are measured, efficiency and stability are addressed, as well as the economic data showing an excellent cost of production of ca. 2 US $ per Wp for a one MWp production volume. The required steps leading towards end-user products and the challenges to overcome are also addressed.

Industrially viable assembly techniques have been established for dye solar cells to be used in low light (indoor) and outdoors applications. Stability behavior under thermal stress, UV and visible light irradiation is investigated, in particular in view of real outdoors conditions. Solid-state dye solar cells were also assembled, where an organic p-type semiconductor material replaces the currently employed liquid electrolyte.

Strategies towards flexible solid state solar cells based on nanocrystalline titanium oxide and organic hole conductor were investigated. For the flexible cell geometry a metal foil was used as substrate and a semi-transparent gold layer as counter electrode which allows light transmission (back illumination). The device performance of solid state cells based on SnO2:F coated glass on the one hand and a metal foil on the other hand were characterized and compared by measuring the current voltage curves on back and front illumination.

All screen printed Dye Sensitized Solar cell modules were fabricated and demonstrated excellent electrical performances thanks to a monolithic interconnection based on highly conductive carbon layers. Attained efficiency at 1000 W/m2 is 6 % with a fill-factor of 0.7. This monolithic module is very elegant to manufacture since the layers, including nano- TiO2 spacer, catalytic active layer, conductive carbon and sealing are all printed. Such a module only requires one transparent conductive substrate which allows substantial manufacturing cost reductions. Moreover, only one co-firing cycle is sufficient, thus lowering the required energy at production. In addition, a quick staining process enables in-line production techniques. Modules of 10 x 10 cm are now being built for sampling and performance testing.

The cell structure concepts and materials to build solid-state dye solar cells based on nanocristalline titanium oxide and an organic hole conductor were investigated. The substrate cell is based on a metal foil and a semi-transparent gold window on top of the cell structure and the superstrate cell is deposited on ITO coated polymer foil replacing the traditional conductive glass as transparent substrate. Steel, titanium and polymer foil based cell were assembled. The polymer/ITO cell gave only small currents as the materials are far from optimal in that configuration, but an efficiency of 0.8 % was obtained on a Ti-foil based cell.