Large area optimized thin film nano solar cells on metal sheets
M. Toivola, T. Peltola, K. Miettunen, J. Halme, K. Aitola, P.D. Lund
Helsinki University of Technology, FI
Keywords: dye-sensitized solar cell, metal substrate, upscaling
Abstract:We have upscaled stainless steel based dye-sensitized solar cell (DSC) from small, 0.32 cm2 active area laboratory sized test cells to 6 cm x 6 cm large area ”minimodule”. This is a continuation to our previous research, in which stainless steel (StS) was identified as a suitable substrate for the DSC photoelectrode (PE). Steel’s superior conductivity enables drastic enlargening of the cell size and steel PEs can be sintered at high temperatures which yields stable and high quality TiO2 films. Steel is also flexible, mechanically robust and cost-efficient substrate. To keep the cell structure completely flexible and suitable for industrial-type roll-to-roll manufacturing, sputter-platinized ITO-PET or ITO-PEN plastic foils (thermally platinized glass as a reference) were employed as the counter electrodes (CE). The best large cell efficiencies obtained this far are 3.4 % with a StS PE and glass CE and 2.5 % with a StS PE and ITO-PET CE. These are very promising considering the best reported small cell efficiencies with the same substrate materials are around 4 % at the moment. Also, a semi-empirical mathematical model was developed, with which the large cell geometry could be optimized to minimize the resistive losses in the cell.