Synthesis And Performance Of Efficient Photoanode Light Scattering Layer Materials In Dye Sensitized Solar Cell (DSSC)

Dye-sensitized solar cells?DSSCs?provide a promising alternative to conventional silicon-based solar cells on account of their advantages,such as lower manufacturing costs and relatively higher conversion efficiencies.In particular,TiO₂photoanode plays a crucial role due to its light-harvesting capacity,which largely determines final photoelectric conversion efficiency?PCE?of DSSCs.However,conventional P25 TiO₂ nanocrystalline photoanodes exhibit weak light scattering ability due to nanometer particle size,resulting in lower light-harvesting efficiency?LHE?,which limit the improvement of PCE.Herein,we make efforts to introduce large size light scattering materials,which will enhance the LHE of photoanode and thus the PCE of DSSC will be improved.In this work,TiO₂ microspheres have been synthesized via hydrothermal method?A series of TiO₂ microspheres have been synthesized by controlling the reaction conditions.Structure and morphology of the synthesized TiO₂ microspheres were characterized by SEM,TEM and XRD.These synthesized TiO₂ microspheres were then used as light scattering materials in photoanode.Photovoltaic performance and electrochemical impedance spectroscopy?EIS?of the fabricated DSSCs were further investigated.Under the optimum conditions?the hydrothermal time is 10h and the hydrothermal temperature is 180?,the mass of polyvinyl pyrrolidone is 2g,the volume of KCl saturated solution is 15mL?,the synthesized TiO₂ microsphere exhibited a diameter of¹?m with a rough surface.The obtained double-layered DSSC exhibited the highest PCE of 6.03%.This improvement could be ascribed to the introduction of large size TiO₂ microspheres used as light scattering materials in photoanode,which enhanced the light harvest efficiency,leading to the higher photo-generated current.In order to further investigate the photoanode light scattering capacity determined by different morphologies of light scattering materials,we prepared cake-like TiO₂ by annealing hydrothermal synthesized Ti-based metal-organic frameworks?MOFs?MIL-125.Structure and morphology of these annealed materials were characterized by SEM,TEM and XRD.These annealed materials were then used as an efficient scattering layer in photoanode.Under the optimum conditions?the hydrothermal temperature is 180?and the hydrothermal temperature is 24h,the mass of terephthalic acid is 2.5g,the volume of titanium isopropoxide is 1.4 ml?,the MIL-125 precursor was prepared.The annealed materials exhibited cake-like morphology,with an average diameter and thickness of around 700nm and 200 nm,respectively.The obtained double-layered DSSC exhibited the highest PCE of 6.91%.The improvement of DSSC could be ascribed to synthesized TiO₂ its special cake-like structure and relatively high surface area.