Virus-templated self-assembled single-walled carbon nanotubes for highly efficient electron collection in photovoltaic devices

Abstract

The performance of photovoltaic devices could be improved by using rationally designed nanocomposites with high electron mobility to efficiently collect photo-generated electrons. Single-walled carbon nanotubes exhibit very high electron mobility, but the incorporation of such nanotubes into nanocomposites to create efficient photovoltaic devices is challenging. Here, we report the synthesis of single-walled carbon nanotube-TiO(2) nanocrystal core-shell nanocomposites using a genetically engineered M13 virus as a template. By using the nanocomposites as photoanodes in dye-sensitized solar cells, we demonstrate that even small fractions of nanotubes improve the power conversion efficiency by increasing the electron collection efficiency. We also show that both the electronic type and degree of bundling of the nanotubes in the nanotube/TiO(2) complex are critical factors in determining device performance. With our approach, we achieve a power conversion efficiency in the dye-sensitized solar cells of 10.6%.

Carbonaceous Dye‐Sensitized Solar Cell Photoelectrodes

“…Guai et al108 later showed a similar finding to that of Dang et al107 namely that the s‐SWCNTs suppress the charge recombination in DSSCs and thereby enhance the overall efficiency. The improved performance of DSSC was because of the increased electron diffusion length by s‐SWCNTs, leading to higher electron collections.…”

“…In 2004, Jang et al95 were the first to report using CNTs in the photoelectrode of DSSCs and they achieved a 25% increase in the J sc compared to the CNTs–free cell. Since this significant improvement in the DSSC performance was demonstrated by these authors using CNTs, considerable attention has been paid to the research on this topic 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109. For instance, Lin et al99 prepared bilayer structured photoelectrode films composed of multi‐walled carbon nanotubes (MWCNTs)–TiO 2 /TiO 2 which when used in DSSCs exhibited two times higher PV efficiency than the cell fabricated with the bare TiO 2 film.…”

“…Several researchers have used CNT materials in TiO 2 photoelectrode films to boost the PV efficiency of DSSCs 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109. It can be clearly seen from Figure 9 that the recorded efficiencies of CNTs/TiO 2 photoelectrodes based DSSCs vary from 4.1% to 10.6% depending on the experimental conditions and applied techniques.…”

“…It can be clearly seen from Figure 9 that the recorded efficiencies of CNTs/TiO 2 photoelectrodes based DSSCs vary from 4.1% to 10.6% depending on the experimental conditions and applied techniques. So far, the best efficiency of CNTs/TiO 2 photoelectrode based DSSC has been achieved by Dang et al107 who introduced multiple genes of a virus into s‐SWCNTs based aqueous solution. The prepared pastes composed of virus/s‐SWCNTs/TiO 2 were deposited onto FTO glass substrates using a doctor blade technique.…”

“…The improved performance of DSSC was because of the increased electron diffusion length by s‐SWCNTs, leading to higher electron collections. Notably, the s‐SWCNTs possess a non‐continuous band structure, while the m‐SWCNTs have zero bandgap 107. So, in the 3D networks of s‐SWCNTs/TiO 2 , the electrons, transferred from the conduction band of TiO 2 , can be transported to the conducting oxide film without charge recombination because the higher energy barrier of s‐SWCNTs compared to m‐SWCNTs blocked the back flow of dye‐injected electrons to the electrolyte (see Figure 10 a).…”