Quasi-solid-state dye-sensitized solar cells: Pt and PEDOT:PSS counter electrodes applied to gel electrolyte assemblies

In this paper we present an attempt to substitute liquid electrolyte (LC) dye-sensitized solar cells (DSSCs) by quasi-solid-state constructions (SC) for semi-transparency application adopting organic/inorganic gels in combination with standard (Pt based) and alternative (PEDOT:PSS based) counter electrodes. Gel polymer electrolytes are prepared by incorporating a liquid electrolyte into a polymer matrix such as polymethyl-methacrylate (PMMA) using propylene carbonate (PC) as gelling solvent. SC employing gel electrolytes with a high content in PC have been shown to exhibit increased lifetime up to 70 h under A.M. 1.5 irradiation. Counter electrodes were prepared by an airbrushing and tape casting technique of Pt salt solutions or by spin coating of commercial PEDOT:PSS solution. PEDOT:PSS counter electrodes were found to show similar I3−/I− catalytic activities to Pt based counter electrodes and the best SC obtained gave a short circuit current of 2 mA cm−2 and a open circuit voltage of 625 mV.