Fast TiO₂Sensitization Using the Semisquaric Acid as Anchoring Group

Abstract

Metal-free dye molecules for dye-sensitized solar cells application can avoid some of the typical drawbacks of common metal-based sensitizers, that are high production costs, relatively low molar extinction coefficient in the visible region, limited availability of precursors, and waste disposal issues. Recently we have proposed an innovative organic dye based on a simple hemi-squaraine molecule (CT1). In the present work, the effect of the sensitization time of the TiO2photoelectrode in the dye solution is studied with the aim of optimizing the performance of CT1-based DSCs. Moreover, the addition of the chenodeoxycholic acid (CDCA) as coadsorbent in the dye solution at different concentrations is investigated. Both CT1-sensitized mesoporous TiO2photoanodes and complete solar cells have been fully characterized in their electrical and absorption properties. We have found that the best photoconversion performances are obtained with 1 hour of impregnation time and a 1 mM CDCA concentration. The very fast kinetics in dye adsorption, with optimal sensitization steps almost 15 times faster than conventional Ru-based sensitizers, confirms the theoretical predictions and indicates a strong interaction of the semisquaric acid group with the anatase surface. This result suggests that this small molecule can be a promising sensitizer even in a continuous industrial process.

A Chemometric Approach for the Sensitization Procedure of ZnO Flowerlike Microstructures for Dye-Sensitized Solar Cells

“…Subsequently, a circular shaped ZnO layer was deposited using the tape-casting technique on FTO covered glasses (7 Ω/sq, Solaronix) preliminarily cleaned using a procedure described elsewhere. 34 The coated films were initially dried at 90 °C for 30 min and then thermally treated at 450 °C for 10 min in air. The final thickness of ZnO film was about 14 μm, as measured by using a profilometer (P.10 KLA-Tencor Profiler).…”

“…ZnO flowerlike particles were dispersed in a solution containing acetic acid (1 vol %), ethanol (67 vol %), and water (33 vol %) in a weight ratio of 1:2 (ZnO/solution) and then sonicated for 4 h in order to obtain a homogeneous paste. Subsequently, a circular shaped ZnO layer was deposited using the tape-casting technique on FTO covered glasses (7 Ω/sq, Solaronix) preliminarily cleaned using a procedure described elsewhere . The coated films were initially dried at 90 °C for 30 min and then thermally treated at 450 °C for 10 min in air.…”

“…Different dye immersion times and different values for the pH and the dye concentration of the sensitizing solution were investigated. Counter electrode fabrication and cell assembly procedures were reported in previous works. , A commercial liquid electrolyte solution (Iodolyte AN 50, Solaronix) was employed and, where specified, N -methylbenzimidazole was added in the electrolyte solution.…”

TiO 2 nanotubes as flexible photoanode for back-illuminated dye-sensitized solar cells with hemi-squaraine organic dye and iodine-free transparent electrolyte

“…3a), that revealed a noticeable decrease in the 466 photocurrent of the quasi-solid cell. As it is known, howev- Moreover it has to be noted a red-shift of the IPCE spec-480 tra with respect to those presented in our previous works 481 [28,29]. Such shift is present in back-side illumination con-482 ditions [53] and has been ascribed to the fact that the long …”

“…Also nanotube carpets directly grown 96 by anodic oxidation on flexible metal foils have been sug-97 gested for a better transport of the photogenerated charges 98 [25,26]. In particular, our group has developed vertically 99 oriented not-curling free-standing TiO 2 NT membranes as 100 alternative photoanode material [27], hemi-squaraine 101 metal-free organic dye molecule (CT1) to be exploited in 102 substitution of the Ru-based N719 sensitizer [28][29][30], and 103 quasi-solid electrolytes such as UV-crosslinked polymer 104 membrane [31] and biopolymeric gels [32]. 105 It has however to be noted that despite the impressive 106 large number of research articles published on innovative 107 materials and concepts, the obtainable effects when they 108 are blended into a single device have been presented only 109 in few works [33][34][35][36].…”