Benzothiadiazole derivatives functionalized with two different (hetero)aromatic donor groups: Synthesis and evaluation as TiO 2 sensitizers for DSSCs

Abstract

A series of benzothiadiazole-based push-pull heterocyclic systems were synthesized and characterized in order to study the variations induced by different aromatic and heterocyclic donor groups in the optical, electronic and photovoltaic properties of DSSCs prepared with the respective cyanoacetic acid derivatives. The organic sensitizers bear a 5-hexyl-2,2′-bithienyl or N,N-diphenylanilino donor moieties conjugated with a thienyl-benzothiadiazole spacer functionalized with the electron acceptor/anchoring cyanoacetic acid group. The solar cell based on TiO 2 sensitized with the novel dye bearing the 5-hexyl-2,2′-bithienyl donor, exhibited a power conversion efficiency of 0.95 % due the inefficient electron injection. Co-adsorption studies of the same dye resulted in enhanced photovoltaic conversion efficiency of 2.49 %, which represents an improvement of cell efficiency of 260 %. The sensitizer bearing the N,N-diphenylanilino donor exhibited 4.51 % power conversion efficiency, that was further enhanced by co-sensitization to 5.22 % efficiency.

Investigations of New Phenothiazine-Based Compounds for Dye-Sensitized Solar Cells with Theoretical Insight

“…On the other hand, for efficient electron injection, the energy state level (LUMO) should be above that of the conductivity band of TiO2 (4.0 eV) [39]. Considering the electrochemical data, it can be [37]. Compound 2a was characterized by a non-reversible oxidation process.…”

“…The oxidation process is important for compounds tested as dyes in DSSCs. The compounds should exhibit similar potential to the potential of the pair I 3 − /I − being 0.42 V, enabling the regeneration of dyes by I − in the electrolyte[37]. Compound 2a was characterized by a non-reversible oxidation process.After three scans, no product of electrode surface was found (FigureS14).…”

Visible light-induced cationic photopolymerization by diphenyliodonium hexafluorophosphate and benzothiadiazole dyes

“…A long-conjugated molecule forms from the structure, which broadens the longwavelength absorption spectrum. In the field of dye-sensitized solar cells, it is reported that benzothiadiazole-based dyes can match the simulated solar light [28][29][30][31]. In addition, 4,7-dibromo-2,1,3-benzothiadiazole is very reactive for nucleophilic substitution reactions and coupling reactions [32].…”

Push-Pull Heterocyclic Dyes Based on Pyrrole and Thiophene: Synthesis and Evaluation of Their Optical, Redox and Photovoltaic Properties

“…It is also well known that the position of the heterocyclic nuclei on the π-spacers is an important factor. Both types of heterocycles, electron-rich, such as thiophene and pyrrole, and electron-deficient, such as azole and azine derivatives, i.e., (benzo)thiazole benzothiadiazole, pyridine, etc., can act simultaneously as π-bridges and electron donors or acceptors, respectively [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53].…”