title: Enhancing dye-sensitized solar cell performances by molecular engineering: highly efficient π-extended organic sensitizers.
abstract: This study deals with the synthesis and characterization of two π-extended organic sensitizers (G1 and G2) for applications in dye-sensitized solar cells. The materials are designed with a D-A-π-A structure constituted by i) a triarylamine group as the donor part, ii) a dithienyl-benzothiadiazole chromophore followed by iii) a further ethynylene-thiophene (G1) or ethynylene-benzene (G2) π-spacer and iv) a cyano-acrylic moiety as acceptor and anchoring part. An unusual structural extension of the π-bridge characterizes these structures. The so-configured sensitizers exhibit a broad absorption profile, the origin of which is supported by density functional theory. The absence of hypsochromic shifts as a consequence of deprotonation as well as notable optical and electrochemical stabilities are also observed. Concerning the performances in devices, electrochemical impedance spectroscopy indicates that the structural modification of the π-spacer mainly increases the electron lifetime of G2 with respect to G1. In devices, this feature translates into a superior power conversion efficiency of G2, reaching 8.1%. These results are comparable to those recorded for N719 and are higher with respect to literature congeners, supporting further structural engineering of the π-bridge extension in the search for better performing π-extended organic sensitizers.
authors: DICATECh-Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica, Politecnico di Bari, Via Orabona, 4 I-70125 Bari (Italy).
authors: Roberto
authors: R
authors: Grisorio
authors: Luisa
authors: L
authors: De Marco
authors: Rita
authors: R
authors: Agosta
authors: Rosabianca
authors: R
authors: Iacobellis
authors: Roberto
authors: R
authors: Giannuzzi
authors: Michele
authors: M
authors: Manca
authors: Piero
authors: P
authors: Mastrorilli
authors: Giuseppe
authors: G
authors: Gigli
authors: Gian Paolo
authors: GP
authors: Suranna
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D011211:Electric Power Supplies; D004563:Electrochemistry; D004579:Electron Transport; D004738:Engineering; D008958:Models, Molecular; D008968:Molecular Conformation; D012993:Solar Energy; D013830:Thiadiazoles / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D013830:Thiadiazoles; C015700:benzo-1,2,3-thiadiazole
keywords: benzothiadiazole; dye sensitized solar cell; light-harvesting; structure-property relationship; π-extended organic sensitizer