Abstract
In this study, several attempts have been made to fabricate highly efficient flexible dye-sensitized solar cells based on quasi-solid state electrolytes. Ionic gel electrolytes by dispersing various nanoparticles or polymers into ionic liquid electrolytes and assembled DSCs were prepared. The DSCs device based on the ionic gel electrolyte solidified by TiO2 nanoparticles yielded the best performance. Three different kinds of the titanium dioxide (20nm pure anatase, P25 and ST01) were dispersed in solvent to prepare binder-free nanocrystalline TiO2 pastes. Incorporation of large nanoparticles (100 nm) has been employed as light-scattering centers to increase the optical length in the film, and an enhanced light-harvesting has effect by scattering. A static mechanical compression technique as the post-treatment is employed to the flexible ITO/PEN photoelectrodes in order to enhance the particles connection. The construction of the film was optimized to elicit high photovoltaic performance. Effect of the loading of TiO2 thickness of TiO2 film on the photovoltaic performance was first investigated with the sensitizer N719 in combination of TiO2 solidified quasi-solid electrolyte. A solar cell with platinum-coated FTO glass counter electrode and ITO/PEN photoelectrode, prepared by an ethanol based low-temperature TiO2 paste composed of a mixture of P25 (21nm, 25% rutile and 75% anatase) and 100 nm anatase TiO2 particles, yielded highest conversion efficiencies of 6.53% under 1 sun illumination. All plastic DSCs are also investigated by applying Pt-sputtered or Pt-spread ITO/PEN counter electrodes. The all plastic DSC with Pt-sputtered ITO/PEN counter electrode yields a light to electricity conversion efficiency of 4.67% under 1 sun illumination.