Photovoltaic characteristics and dye regeneration kinetics in D149-sensitized ZnO with varied dye loading and film thickness

Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells

“…The IPCE increases as the adsorption time increases. 36 The transient absorption band around 700-900 nm is attributed to the oxidized N719 species (cation radical, N719 +• ). The IPCE is saturated at about 75% efficiency for wavelengths ranging between 500 and 550 nm.…”

Statistical TiO2/dye-mass dependence and dye-regeneration efficiency on dye-sensitized solar cells

“…Here, because the TiO 2 film thickness, the TiO 2 particle properties, and the adsorbed dye-mass are particularly critical to the DSC performance of relevance to electron diffusion and transport, effectiveness and optimization of the TiO 2 film thickness have been extensively studied through an understanding on charge-transfer kinetics and charge photodynamics, which is related with charge recombination and dye regeneration lifetimes [8][9][10][11]; the dye is regenerated by the process that an electron excited from the dye molecules is transferred into the TiO 2 conduction band and followed by the oxidized dye, forming a N719 dye cation radical (N719 dye + ) is subsequently reduced by electron donation from the electrolyte containing I À . The oxidized dye may also recombine with electrons injected in the TiO 2 surface, which causes the charge recombination process [12][13][14]. An in-depth study of charge-transfer kinetics and charge photodynamics in interface between solid and liquid is still an ongoing and interesting issue for photoelectrochemistry.…”

Effect of TiO2 Photoanodes Morphology and Dye Structure on Dye-Regeneration Kinetics Investigated by Scanning Electrochemical Microscopy

“…However, this effect may be counteracted and even overcompensated by increased possibilities for loss processes at a larger inner surface [24] and mediator mass transport limitation inside the porous network [25,26] as was found from the analysis of films with thicknesses below 6 µm [24,27,28]. There are indications that, on the one hand, thicker photoanodes produce high open-circuit photovoltages resulting in enhanced photoconversion efficiency [28,29] and on the other hand exhibit a higher area for back electron transfer reactions [30]. It has been reported that the use of thin films leads to a more effective dye-regeneration kinetics favored by the limited back electron transfer reaction and faster mediator diffusion through the porous film [29].…”

“…There are indications that, on the one hand, thicker photoanodes produce high open-circuit photovoltages resulting in enhanced photoconversion efficiency [28,29] and on the other hand exhibit a higher area for back electron transfer reactions [30]. It has been reported that the use of thin films leads to a more effective dye-regeneration kinetics favored by the limited back electron transfer reaction and faster mediator diffusion through the porous film [29].…”

“…Despite extensive work to improve photovoltaic characteristics of the TiO 2 photoanode, little information has been obtained about the quantitative effect of post-TiCl 4 treatment and sensitization processes on the dye-regeneration kinetics (process (4) in Figure 1). In this regard, scanning electrochemical microscopy (SECM) provides an evaluation of the dye regeneration rate constant (k ox ) for process 4 in Figure 1, that measures the ability of the mediator to reduce the photo-oxidized dye adsorbed on the photoanode [29,31,32]. In this work, SECM analysis is applied to passivated TiO 2 photoanodes sensitized with the all-organic dye molecules D358 or DN216 (Figure 2) [33,34].…”