Synthesis and properties of new benzothiadiazole-based push-pull dyes for p-type dye sensitized solar cells. (January 2018)

• Record Type: Journal Article
• Authors: Farré, Yoann; Raissi, Mahfoudh; Fihey, Arnaud; Pellegrin, Yann; Blart, Errol; Jacquemin, Denis; Odobel, Fabrice
• Is Part Of: Dyes and pigments. Volume 148(2018)
• Page Start: 154
• Page End: 166
• Publication Date: 2018-01
• Subjects: Push pull dyes -- Benzothiadiazole -- Fluorene linker -- Dyad -- Dye sensitized solar cells -- Tandem cells; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2017.08.055
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: We report the synthesis of three new push-pull dyes specially designed for the sensitization of mesoporous p type semi-conductor NiO for the construction of p type dye sensitized solar cells (pDSC). Their structure stems from the conjugation of the well-known tris(carboxy-arlyamine) anchoring moiety to a benzothiadiazole acceptor through a fluorene (PP1 ) or thiophene-fluorene linker (PP2 ). Appending a NDI secondary acceptor ontoPP2 yielded a dyad (PP2-NDI ). The push-pull structure is here particularly adapted to the sensitization of p-type semi-conducting materials. All three dyes were investigated by spectroscopic and electrochemical techniques, and their electronic properties were modelled by TD-DFT. In all cases, the new sensitizers exhibit adequate absorption features (spanning from 400 nm to 600 nm, extinction coefficients between 20000 and 27000 M −1 cm −1 ) and their thermodynamic parameters are all in favor of efficient interfacial charge transfers involving NiO. pDSC were constructed with all three dyes; high photoconversion efficiencies (PCE) were reached, especially in the case of dyadPP2-NDI (Jsc = 5.90 mA/cm 2, Voc = 143 mV, FF = 33.8%, PCE = 0.29%), due to a combination of outstanding electronic properties and increased charge separation state lifetime. Tandem DSC (tDSC) composed of a TiO2 photoanode sensitized by the dyeD35 and a NiO photocathode sensitized byPP2-NDI were assembled with two different electrolytes (I3 − /I − or T2 /T − based electrolytes). The latter gave PCE among the best ever reported for tDSC (Jsc = 5.90 mA/cm 2 ; Voc = 896 mV; FF = 63%, PCE = 2.80% in the case of the I3 − /I − electrolyte, Jsc = 4.52 mA/cm 2, Voc = 840 mV, FF = 60% and PCE = 2.27% for T2 /T − based devices) unraveling the significance of the new dyes presented in this study. Graphical abstract: Highlights: New push pull dyes based on a benzothiadiazole-π-trisarylamine skeleton are designed for NiO pDSC. Highly performant pDSC were obtained owing to properly vectorialized photo-induced hole transfer and intense charge transfer absorption. The best performing dye is thePP2-NDI dyad; increased performances are due to decreased geminate charge recombination. The association of aPP2-NDI /NiO and aD35 /TiO2 photoelectrodes afforded a tandem DSC with a 2.80% efficiency.