Structurally simple D–A-type organic sensitizers for dye-sensitized solar cells: effect of anchoring moieties on the cell performance

Tailoring the Optical Properties of Organic D‐π‐A Photosensitizers: Effect of Sulfur Introduction in the Acceptor Group

“…At this stage, we turned our attention to the synthesis of thioamide 1‐SN , since we also wanted to investigate its use as a potential sensitizer for DSSCs, in analogy with some literature reports describing the possibility to anchor organic dyes to TiO 2 by means of a thioamide‐like moiety (usually inserted within a heterocyclic structure) . Accordingly, we first converted acid DF15 to the corresponding amide 7 by means of sequential reactions with oxalyl chloride and gaseous ammonia, and then reacted the latter with LR under mild conditions to obtain the desired product in good overall yield (Scheme , top).…”

“…0.1 %, Figure S7). From this observation, it seems that the thioamide group per se is not adequate to ensure a proper adsorption of the dye on the semiconductor layer, suggesting that sensitizer binding should take place through a different functional group also in the above‐mentioned cases of “thioamide‐like” fragments embedded in more complex heterocyclic anchoring moieties (thiobarbituric acid, 2‐aminothiazol‐4‐one) …”

“…As detailed below, while the synthesis of thiocarboxylic acid 1‐SO proceeded smoothly, isolation of dithiocarboxylic acid 1‐S 2 was not successful due to its insufficient stability: nevertheless, the relative spectroscopic properties could be assessed and compared to those of DF15 by scrutinizing the corresponding benzylic esters (Figure ). We also prepared thioamide 1‐SN to investigate the capability of such functional group to bind TiO 2 , in analogy with the above‐mentioned reports . Spectroscopic characterization of the new dyes was complemented by transient absorption spectroscopy (TAS) measurements, which allowed us to evaluate the kinetics of photoexcitation and electron injection into the semiconductor.…”

“…Chauhan and co‐workers reported the application of ferrocenyl‐containing compounds bearing a dithiocarbamate coordinating group and the corresponding complexes with various metals (including Zn, Cd, Hg, Cu, Pd, Pt, Co) as sensitizers or co‐sensitizers in DSSCs, recording efficiencies close to those obtained with reference dye N719 under the same conditions . A few groups independently explored the possibility to use thiobarbituric acid as an anchoring group and compared the performances of the corresponding dyes with those of their oxygenated analogues: monodentate dyes based on simple phenyl or carbazole backbones,, or dyes with two anchoring groups on the same molecular structure were investigated. Regardless of structural modifications, computational studies and IR spectroscopic analyses indicated that the thioamide group seemed to be involved in bonding to the semiconductor, but efficiencies remained quite low (well below 1 %).…”

Synthesis and structure of push–pull merocyanines based on barbituric and thiobarbituric acid

“…Studies of molecules with different lengths of the -bridge between the donor and acceptor groups (Ortiz et al, 1994, Vá zquez-Vuelvas et al, 2011 have demonstrated their different properties. Some non-linear optical studies were made on compounds with very similar structures to those presented here (Ikeda et al, 1991;Chamberlain et al, 1980;Kulinich et al, 2008), which vary by substitutions attached to the donor or acceptor groups (Song et al, 2005;Naik et al, 2017;Hirshberg et al, 1955). Almost all those studies were carried out in solution.…”