Synthesis and characterization of squaric acid based NIR dyes for their application towards dye-sensitized solar cells

Polymethine Dyes in Hybrid Photovoltaics: Structure–Properties Relationships

“…Also in 2010, Pandey et al observed better performances with alkyl and fluoro‐alkyl unsymmetrical squaraine dyes. In particular, a symmetrical dye, coded SQ‐A84 or SQ‐385 (or SQ‐186) [S43], showed lower photocurrent and efficiency when directly compared with its monoanchored analogous (SQ‐D84 or SQ‐485 [S18]) (Figure 8). The conclusion was that the attachment of an anchoring group in the aromatic ring and the creation of an unsymmetrical molecule facilitate the effective electron injection from photoexcited dye to the conduction band of TiO 2 , because of the unidirectional charge flows, enhancing photovoltaic performance.…”

Effect of nature of anchoring groups on photosensitization behavior in unsymmetrical squaraine dyes

“…The dyes SQ-A and SQ-B bearing carboxylate and cyanoacrylate functionality were synthesized following the methods developed in our earlier reports [10,23]. SQ-C bearing thiophene bridged cyanoacrylate has been synthesized by modifying the method developed by Shi et al [22].…”

“…SQ-C bearing thiophene bridged cyanoacrylate has been synthesized by modifying the method developed by Shi et al [22]. The intermediates 2,3,3-trimethyl-3H-indole-5-carboxylic acid (4a) and 3-(5-Bromo-1-butyl-3,3-dimethyl-2,3-dihydroindol-2-ylidenemethyl)-4-hydroxy cyclobut-3-ene-1,2-dione (10) were synthesized according to the reported procedures [9,24]. [2].…”

“…Squaraine dyes showing intense and sharp absorption in the NIR region and high molar extension co-efficient have recently been used as potential NIR sensitizers for DSSCs [6][7][8]. Report of 4.5% photoconversion efficiency by Yum and et al [9] on unsymmetrical squaraine dye bearing carboxylic acid anchoring group directly attached to its indole chromophore opened up the new idea that dyes bearing carboxylic group directly linked to aromatic chromophore are superior in performance as compared to that of their alkyl side chain carboxy substituted dye counterparts [10]. Afterward, several research groups followed the same idea and reported many squaraine dyes bearing carboxylic acid anchoring group attached to various heterocyclic and aromatic donors as potential NIR sensitizers for DSSCs [11][12][13][14][15].…”

Fast TiO2Sensitization Using the Semisquaric Acid as Anchoring Group

“…In comparison to the Ru-based sensitizers, however, organic dyes exhibit lower conversion efficiencies, due to the formation of dye aggregates on the semiconductor surface and to their narrow light absorption bands in the visible region. Therefore, several efforts have been made to study organic dye molecules with broader spectral responses and with anchoring group that strongly binds to the nanocrystalline TiO 2 surface, ensuring electron coupling with the substrate [7][8][9][10].…”