Monolithic series-interconnected modules—characterized by a structure similar to that of amorphous-silicon solar-cell architectures—are the most promising DSC-module type for mass production. However, these modules neutralize the unique transparency advantage of DSCs, because they use black, carbon-based counter electrodes (CEs) as well as rutile-based opaque separators between the photo-electrodes of porous anatase and the corresponding CEs.
The researchers have recently developed transparent CEs composed of platinum (Pt)-loaded tin-doped indium-oxide (In2O3:Sn, or ITO) nanoparticles and separators made of silicon-dioxide nanoparticles. Three-layered electrodes consisting of photo-electrodes, the newly developed separators, and our new CEs were stacked on glass plates covered with conductive oxide layers by successive screen printing, followed by sintering and sensitization with a red dye. A new process was applied to seal the electrodes filled with a liquid electrolyte, using transparent damp-proof films with thermoplastics as back covers. This ensures both good durability and easy production.
The detailed performance of the new materials and their durability when exposed to full sunlight at 60°C were examined using small, monolithic single cells (not series interconnected). Their fabrication process was the same as that of the full modules, except for the sealing method.
The performance of the small cells improved during the first 100h of exposure to sunlight.
Researchers propose a new application of transparent DSC modules, a surface light-emitting plate driven by solar energy. The plate consists of a transparent DSC module (using a yellow dye), an electroluminescent (EL) panel mounted just below the solar-cell stack, and a rechargeable battery. Electricity generated by the DSC module and stored in the battery during the daytime is supplied to the EL panel at night. Orange emission from the EL panel passes through the DSC module with little absorption loss and illuminates the surroundings. The newly developed modules will broaden the applicability of DSCs.
