Sodium Hydroxide Pretreatment as an Effective Approach to Reduce the Dye/Holes Recombination Reaction in P-Type DSCs

Abstract

We report the synthesis of a novel squaraine dye (VG21-C12) and investigate its behavior as p-type sensitizer for p-type Dye-Sensitized Solar Cells. The results are compared with O4-C12, a well-known sensitizer for p-DSC, and sodium hydroxide pretreatment is described as an effective approach to reduce the dye/holes recombination. Various variable investigation such as dipping time, dye loading, photocurrent, and resulting cell efficiency are also reported. Electrochemical impedance spectroscopy (EIS) was utilized for investigating charge transport properties of the different photoelectrodes and the recombination phenomena that occur at the (un)modified electrode/electrolyte interface.

Efficiency enhancement of ruthenium-based DSSCs employing A–π–D–π–A organic Co-sensitizers

“…Basically the longer electron lifetime leads to a better suppression of back reactions between the injected electrons and the electrolyte, which usually leads to improvement of the V OC . [47][48][49] The V OC values of the co-sensitized devices obviously follow the same order as the s eff values, clearly showing the great effect of anchoring groups and co-sensitization on the electron recombination processes between the electrolyte species and electron transfer into the TiO 2 semiconductor lm. Hence, the decrease in the V OC for the IMA5 device can be explained by the faster recombination relative to that of the IMA5+IMA2 cosensitized device, which can be attributed to the increase in dye loading on the surface of the TiO 2 by the adsorption of the larger IMA5 complex followed by the adsorption of smaller IMA1-4 molecules in such a way as to ll the gaps between larger IMA5 molecules in the sensitization process, which helps with the formation of a blocking layer covering the complete TiO 2 nanoparticle owing to increased dye loading.…”

A New Series of EDOT Based Co-Sensitizers for Enhanced Efficiency of Cocktail DSSC: A Comparative Study of Two Different Anchoring Groups

“…The observed trend of the recombination lifetime was in par with the EIS results and V OC. These results clearly portray the advantage of using co-sensitizers in obtaining decreased recombination rate and increased recombination life time owing to their small size and strong anchoring groups [40,51].…”

“…Increased dye loading was accomplished by the adsorption of larger size N749 molecules onto TiO 2 initially followed by the adsorption of smaller size CSGR molecules in such a way that it would fill the gaps between larger N749 molecules in the process of sensitization. In comparison to N749 molecules, CSGR dyes exhibit higher binding capacity to the TiO 2 surface owing to their small size and strong anchoring group [51]. The back–electron recombination with the electrolyte or dye molecules was further prevented by the formation of a blocking layer covering the complete TiO 2 nanoparticle due to increased dye loading [42,51].…”

“…In comparison to N749 molecules, CSGR dyes exhibit higher binding capacity to the TiO 2 surface owing to their small size and strong anchoring group [51]. The back–electron recombination with the electrolyte or dye molecules was further prevented by the formation of a blocking layer covering the complete TiO 2 nanoparticle due to increased dye loading [42,51]. This eventually led to decreased recombinations and increased V oc values, as evidently observed in case of experimentally co-sensitized DSSC.…”

Application of Metal-Organic Frameworks and Covalent Organic Frameworks as (Photo)Active Material in Hybrid Photovoltaic Technologies

“…Nowadays, organo-metallic sensitizers have been replaced by metal-free dyes keeping relatively high efficiency. These molecules are generally constituted by an electron donor group (e.g., triphenylamine) linked to an acceptor group (e.g., cyanoacrylic acid) [135][136][137] generating an acceptor-π-donor system (A-π-D) with the acceptor moiety close to the electrode surface to assure an effective charge injection. In this respect, MOFs could be used as a sensitizer by using different dye molecules as a building blocks extending the spectral response of the TiO 2 to the visible region.…”