Photoanodes Consisting of Mesoporous Anatase TiO₂ Beads with Various Sizes for High-Efficiency Flexible Dye-Sensitized Solar Cells

Abstract

The synthesis and characterization of TiO 2 beads and the use of them in the photoanodes of all-plastic flexible dye-sensitized solar cells (FDSCs) are reported. Pure anatase TiO 2 beads having different sizes and characteristics were first made using a novel two-step chemical method under different conditions. Photoanodes consisting of the beads as scattering layers were then fabricated. The use of beads largely enhances the dye loading and gives highly effective light scattering, leading to improved light absorbance. The resulting cells were evaluated for the electron diffusion time, electron lifetime, charge collection efficiency, incident photon-to-electron conversion efficiency, electron injection efficiency, and IV characteristics. The pure anatase TiO 2 beads, having low oxygen vacancy concentrations and directional attached grains, lead to more photoelectrons and enhance the electron diffusion, giving very short diffusion times. We have demonstrated for the first time that the use of beads, having diameters ranging from 250 to 750 nm, enhances the light-to-electricity conversion efficiency of FDSCs having plastic substrates by as much as 28%. The cell conversion efficiency is also enhanced from 4.3 to 5.5%.

Microwave-Assisted Hydrothermal Synthesis of TiO2Mesoporous Beads Having C and/or N Doping for Use in High Efficiency All-Plastic Flexible Dye-Sensitized Solar Cells

“…This is primarily due to beneficial scattering effect of the mesoporous beads. 8,9 Fig . 6 shows the J-V curves obtained.…”

“…5 TiO 2 beads have been shown to exhibit an light scattering effect that enhanced the light unitilzation for both rigid [5][6][7] and all-plastic DSCs. 8,9 The mesorporous TiO 2 beads were synthesized using convectional hydrothermal methods. 5,6,8 The conventional hydrothermal route is known to be time-consuming and requires considerable energy to drive the reaction.…”

“…8,9 The mesorporous TiO 2 beads were synthesized using convectional hydrothermal methods. 5,6,8 The conventional hydrothermal route is known to be time-consuming and requires considerable energy to drive the reaction. To overcome these drawbacks, the microwave-assisted hydrothermal route serves as an alternative for the fabrication of nano-sized particles.…”

Ultrathin SnO2 Scaffolds for TiO2‐Based Heterojunction Photoanodes in Dye‐Sensitized Solar Cells: Oriented Charge Transport and Improved Light Scattering

“…However, a well‐recognized hurdle to be overcome for the attainment of higher energy conversion efficiencies for TiO 2 ‐based photoanodes is the short electron diffusion length (10–35 μm, as determined from the product of the electron diffusion coefficient and electron lifetime) of the sintered TiO 2 nanoparticles 7–9. Another issue is that the porous film made of TiO 2 nanoparticles (≈20 nm) generally shows a high transparency and low light‐harvesting efficiency 10. With regard to these issues, recent reports have shown progress in such as array structures11 and carbon hybrid structures,12 but the array structures would largely sacrifice the accessible surface for dye loading, and the carbon materials would absorb incident light intensely and provide recombination sites at the carbon/electrolyte interface.…”

All-Plastic Flexible Dye-Sensitized Solar Cell Based on Solution Synthesized Mesoporous Anatase TiO2Beads

“…As a result, recent efforts have been directed to the synthesis of micro-sized mesopores TiO 2 beads which, however, is still at the infant stage. 13 In this study, we report the synthesis of such mesoporous anatase TiO 2 beads with various sizes and characteristics via a simple two-step solution method involving a sol-gel and a hydrothermal techniques. Such an approach was inspired by the work of Chen et al 5,14 However, the method does not require an additional calcination step.…”