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.
Luminescent concentrator (LC) plates with different dyes were combined with standard multicrystalline silicon solar cells. External quantum efficiency measurements were performed, showing an increase in electrical current of the silicon cell (under AM1.5, 1 sun conditions, at normal incidence) compared to a bare cell. The influence of dye concentration and plate dimensions are addressed. The best results show a 1.7 times increase in the current from the LC/silicon cell compared to the silicon cell alone. To broaden the absorption spectrum of the LC, a second dye was incorporated in the LC plates. This results in a relative increase in current of 5-8% with respect to the one dye LC, giving. Using a ray-tracing model, transmission, reflection and external quantum efficiency spectra were simulated and compared with the measured spectra. The simulations deliver the luminescent quantum efficiencies of the two dyes as well as the background absorption by the polymer host. It is found that the luminescent quantum efficiency of the red emitting dye is 87%, which is one of the major loss factors in the measured LC. Using ray-tracing simulations it is predicted that increasing the luminescent quantum efficiency to 98% would substantially reduce this loss, resulting in an increase in overall power conversion efficiency of the LC from 1.8 to 2.6%.
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.
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.
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.
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.
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.