Natural Sensitizer for Dye-Sensitized Solar Cells Using Three Layers of Photoelectrode Thin Films with a Schottky Barrier

Abstract

Problem statement: This study combines Au nanoparticles with TiO2 nanoparticles to form a Schottky barrier and applies it to the photoelectrode thin film of Dye-Sensitized Solar Cells (DSSCs). Approach: First, com. TiO2 powder (Degussa P25) was put into the alk. soln. to prep. TiO nanotubes (Tnt) by a hydrothermal process. Tnt were sintered at 550° to obtain TntC550 particles and fabricated into a translucent sol by two hydrothermal treatments and baked at 180° to acquire H180 particles. H180 and TntC550 were spread into transparent polymer films by a doctor blade. H180 serves as the first layer and TntC550 the second, with both were sintered at 450°. The third layer uses hydrogen tetrachloroautate (HAuCl4) and trisodium citrate (C6H5Na3O7) to prep. Au nanoparticles by salt redn. Natural dyes of bougainvillea leaves for chlorophyll and blueberries for anthocyanin were employed in this study. Extd. chlorophyll and anthocyanin dyes were also blended in the proportion of 1:1 as a mixed dye and these three different natural dyes were compared to compare their photoelec. conversion efficiencies. Electrolyte and counter electrode (Pt) were added to form the sandwich structure of DSSCs. After being sealed, DSSCs were tasted for fill factor, photoelec. conversion efficiency and incident photon-to-current conversion efficiency. Results: Spherical Au nanoparticles around 27nm were adhered to the TntC550 make a film by self-assembly to complete the prepn. of the third of photoelectrode thin film of DSSCs. Results from the exptl. tests show that for the dye mixts., photoelec. conversion efficiency of DSSCs in this study can reach 0.75% with the VOC of 0.56 V and JSC of 2.93 mA/cm2 and FF of 0.47. Conclusion: It can be seen from the c.d. logarithm and voltage diagram that the prepd. Au nanoparticles produce Schottky barriers on the surface of TiO2. Due to the Schottky barrier, electrons were unable to go back to the dye mols. or electrolyte, thus effectively enhancing the electronic conversion efficiency. [on SciFinder(R)]