Influence of dye dispersion on photoelectric conversion properties of dye-containing titania electrodes

Abstract

The dye-dispersing titania electrodes were prepared from the dye-containing titanium alkoxide sols by a room temperature sol−gel process and steam treatment at 110°C. The spectroscopic and photoelectric conversion properties of the electrodes were investigated in order to clarify the influences of the dye dispersion and the co-dispersion of the two dyes on the electron transfer process. The fluorescein and eosin Y molecules were dispersed into the titania as their monomers. The shapes of the photocurrent action spectra of the fluorescein and/or eosin Y-dispersing titania electrodes well corresponded to those of their absorption spectra because the excited electrons in the dyes were directly injected into the titania conduction band without any interaction between the dye molecules, such as energy transfer.This result indicated that the dye molecules were separately encapsulated in the pores between the titania nanoparticles and tightly adsorbed or bonded to the titania particle surface. The internal quantum efficiency of the photoelectric conversion was higher than that of the conventional dye-adsorbing titania electrodes in which the dye molecules were easily aggregated, thus deactivated by the energy transfer. The co-dispersion of the two dyes on the titania surface allowed to effectively extend the visible light region for the photoelectric conversion.3

Photoelectrochemical properties of dye-dispersing allophane–titania composite electrodes

“…The IPCE values of the dye-dispersing electrodes were higher than those of the dye-adsorbing electrodes due to their strong interaction between the dye and titania as previously reported (Nishikiori et al, 2011c(Nishikiori et al, , 2013b. This result indicated that allophane decreased the electronic conductivity of the electrode causing the back electron transfer.…”

Influences of Acid on Molecular Forms of Fluorescein and Photoinduced Electron Transfer in Fluorescein‐Dispersing Sol–Gel Titania Films

“…In a further study, the steam treatment enhanced the photoelectric conversion efficiency of the fluorescein‐dispersing titania gel due to not only crystallization of the titania gel but also the dye–titania surface complex formation . Based on the results of the time‐resolved spectroscopy and photoelectric measurements, the electron injection process from the dye‐excited states to the titania conduction band is important for the photoelectric conversion.…”

Interaction between dye and zinc in the dye-dispersing ZnO films prepared by a wet process

“…The compounds in such materials exhibit a more efficient light harvesting and fluorescence because they are finely dispersed in the amorphous or nanosized crystalline matrices compared to the conventional dye-adsorbing materials [20][21][22][23]. Therefore, it is expected that such films exhibit a higher function, stability, and performance in various applications.…”

“…Xanthene dyes as laser dyes are available materials for utilizing photoenergy due to their high absorption and fluorescence efficiencies in various visible light regions [32]. It was reported that the hydrothermal treatment of a dye-dispersing amorphous titania film remarkably improved the photoelectric conversion efficiency due to not only its crystallization but also the dye-titanium complex formation [20][21][22][23][24][25][26][27][28][29][30][31].…”

“…The organic dye-dispersing titania gel is suited for the dye-titania complex formation because the dye molecules with carbonyl and/or carboxyl groups are encapsulated in the narrow spaces of the gel [20][21][22][23][24][25][26]. The xanthene dye-dispersing titania gel was prepared without heating from a titanium alkoxide sol containing the dye molecules by the sol-gel method [27][28][29][30][31].…”