High-Performance TiO₂ Photoanode with an Efficient Electron Transport Network for Dye-Sensitized Solar Cells

Abstract

A titanium organic sol was synthesized for the modification of conventional porous TiO 2 photoanodes for dye-sensitized solar cells (DSSCs). As a result, a compact thin TiO 2 film was superimposed on the porous TiO 2 structure as an efficient electron transport network, covering bare conducting substrate surface (FTO) and bridging gaps between TiO 2 nanoparticles, which was confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Dark current measurement suggested that the sol modified photoanode had a remarkably slower recombination rate of the photoelectrons due to the reduced bare FTO surface in comparison with the porous photoanode. The network facilitates the electron transfer in the DSSC process by removing the dead ends of electron pathways, connecting gaps along the electron pathways, and physically enlarging electron pathways, which can be demonstrated by the performance improvement of photocurrent and open-circuit potential. Consequently, the overall energy conversion efficiency of the DSSC was significantly enhanced by 28% after this simple and low-cost organic sol modification. The significant performance improvements observed from the organic sol modified DSSCs suggest that the proposed modification method is a promising alternative to the traditional TiCl 4 modification method.

TiO2: A Critical Interfacial Material for Incorporating Photosynthetic Protein Complexes and Plasmonic Nanoparticles into Biophotovoltaics

“…This mesoporous layer has a large surface area for dye adsorption while maintaining a percolation network for electron transport. Later, a variety of TiO 2 nanorods, nanowires and networks were designed to replace the spherical NPs in photoanode [18][19][20]. These structures are regarded with more efficient electron transport pathway owing to the inherent well-aligned crystalline domains and the greater electron diffusion length [21,22].…”

Highly-ordered arrays of TiO2 thin film for dye-sensitized solar cells fabricated by anodic oxidation process

“…In comparison with NPs, the 1D nanostructure improves electron transport because it has fewer grain boundaries, fewer surface states (i.e., recombination sites), and direct pathways for charges. [3][4][5][6][7] The various methods of synthesizing TiO 2 nanotubes developed to date include the sol-gel method, hydrothermal method, template synthesis and electrochemical anodization. [8][9][10][11][12][13] Of these methods, direct electrochemical anodization of titanium is considered the ideal method of fabricating highly oriented TiO 2 nanotube arrays because the process is very simple and the morphology can be easily controlled by the anodization conditions.…”

Preparationand Characterization of Rutile-anatase Hybrid TiO2Thin Film by Hydrothermal Synthesis

“…When anatase TiO2 is heated above 500 ℃, it is irreversibly converted to the stable rutile structure [16,17]. Besides the physical and chemical properties of TiO2, the geometry of the nanostructured TiO2 electrode is a critical factor of the performance of DSSCs because the contour surface of the TiO2 structure serves as a network of electron pathways [18][19][20]. Recently, various types of nanostructured TiO2 such as nanoparticles, nanotubes, nanowires, and nanorods have been prepared and adopted as electrode materials to improve the performances of DSSCs [21][22][23][24][25].…”