Hybrid Carbon Nanotubes–TiO₂ Photoanodes for High Efficiency Dye-Sensitized Solar Cells

Abstract

We describe a fast and effective procedure for the preparation of high efficiency hybrid photoanodes for dyesensitized solar cells (DSCs), based on nanocrystalline TiO 2 with limited addition of multiwall carbon nanotubes (CNTs). The mixing process between CNTs and TiO 2 nanoparticles is almost instantaneous, which makes it feasible for large-scale fabrication. Enhanced electron lifetime and reduced charge recombination lead to highly increased short circuit current density and overall photoconversion efficiency (from 13.6 mA cm −2 to 16.0 mA cm −2 and from 7.0% to 9.0%, respectively, considering the bare TiO 2 and the optimum CNTs concentration, which is 0.010 wt %), while the small reduction in open circuit photovoltage does not significantly affect cell performances. This result is remarkable since a standard dye molecule (N719) was used and no chemical treatments of the photoanodes prior to cell fabrication were applied (i.e., soaking in TiCl 4 to boost open circuit photovoltage).

Co-sensitization of TiO 2 -MWCNTs hybrid anode for efficient dye-sensitized solar cells

“…The R 2 value for TiO 2 /0.1Mm N 3 + 0.4 mM N719 is smaller than that of 0.04% MWCNTs-TiO 2 /0.1Mm N 3 + 0.4 mM N719 DSSC, proposing charge recombination is greatly reduced owing by incorporation of CNTs. However, the CNTs concentration greater than 0.04 wt.% will lead to the smaller values of R 3 due to a shorter electron lifetime of electrons [30].…”

“…Another major cause of low efficiency of DSSCs is the recombination of injected electrons with the electrolyte (dark current) [27]. The incorporation of CNTs in TiO 2 films may improve the electron transport in DSSCs [28][29][30], owing to the creation of complex interpenetrating networks and favorable electrical conductivity [31,32]. It is supposed that one-dimensional carbon nanostructures allow the photocurrent to flow more efficiently in DSSCs by increasing orientation orders.…”

Charge and energy transfer interplay in hybrid sensitized solar cells mediated by graphene quantum dots

“…Accordingly, intensive efforts were devoted to explore their feasibility as cheaper and eco-friendly materials to replace the components of conventional DSSC, like in the case of alternative counter electrode instead of platinum ones, whose high cost, rarity or risk of corrosion by the redox species are known, and therefore, the significant improvements brought by using carbon nanotubes (CNT) [2], graphene nanosheets [3] or carbon nanoparticles [4] were demonstrated. On the other hand, the incorporation of carbon-based nanomaterials in the photoanode seems to be considered very promising in terms of reducing the photoelectrons' loss and improving its electrical conductivity [5,6]. However, the low surface contact between 1D (e.g.…”

Incorporation of graphene into SnO2 photoanodes for dye-sensitized solar cells

“…However, until now, there has been no report on the use of graphene structures in SnO 2 photoanodes for DSSCs. Moreover, the kinetics of dye adsorption and performance enhancement for carbonaceous photoanodes is still unclear, with some studies suggesting contrary results [21,28,29,31,32]. Therefore, exploring the effect of graphene or reduced graphene oxide (RGO) in SnO 2 photoanode based DSSCs would be valuable.…”