Chemical Sintering of Nanoparticles: A Methodology for Low‐Temperature Fabrication of Dye‐Sensitized TiO₂ Films

Abstract

Optical Characterization: Fluorescence spectra were measured using a fiber-coupled grating spectrometer (Jobin Yvon Triax 190) equipped with a charge-coupled device (CCD) detector. The dye was excited by a 488 nm continuous wave Ar-ion laser (Spectra-Physics Stabilite 2017). The excitation intensity was kept low to avoid degradation of the dye.The reflectance spectra of the films were collected on a fibercoupled grating spectrometer (Jobin Yvon Triax 190) [1] studies have been extensively performed in order to understand the operating mechanism and improve conversion efficiency. As a consequence, solar energy conversion efficiency as high as 11 % has been achieved. [2] In recent years, lightweight plastic-type DSSCs have attracted much attention due to drastic reduction in cost and more extensive applications, such as mobile power for wearable electronic devices. Unlike glass-based DSSCs, the COMMUNICATIONS

A study of TiO2 binder-free paste prepared for low temperature dye-sensitized solar cells

“…At an equivalent TiO 2 film thickness and thermal processing conditions, the overall performance of DSSC prepared in this study was, in some cases, approximately 76% higher than devices reported by Park et al 18 One plausible explanation for such a significant increase in the overall efficiency of the TiO 2 electrode observed in this study could be due to the amount of organic components used to prepare the initial paste. Park et al 18 reported on pastes prepared with an acetic acid:Ti ratio of approximately 10:1 compared with the ratio of 1:1 used in the present work. As the FTIR results suggested [ Fig.…”

“…A similar trend was observed for all pastes at different shear rates with plots of viscosity as a function of shear rates shown in the Supplementary section, Fig. S1 and Table SI. The use of ammonia solution to increase the viscosity of TiO 2 suspension was originally reported by Park et al 18 They attributed this effect to particle-particle interaction being induced by a reduction in the double layer interface. This results from an increase of ion concentration rather than an effect of pH associated with the isoelectric point of titania.…”

“…In our study, the TiO 2 content was kept constant in the final paste, and therefore, no dilution effect took place, with pH of all slurries being below 4; however, the maximum viscosity was observed at 1 wt% (NH 3 /TiO 2 ) concentration. This difference can be explained by the fact that our TiO 2 colloid synthesis utilizes significantly smaller quantities of acetic acid, CH 3 COO À /TiO 2 molar ratio ;1, in comparison to a ratio of 10:1 of acetic acid to titania used by Park et al 18 Titania films were deposited on glass substrates using the doctor blading technique followed by heat treatment at 150°C for 15 min. Under optical imaging, no particle aggregation was visibly detected for both 0.5-TiO 2 and 1-TiO 2 films.…”

“…However, additives for low temperature TiO 2 paste must provide adequate viscosity and volatility to produce uniform porous structures. An interesting method reported by Park et al 18,19 utilizes a binder-free formulation by adding small quantities of ammonia solution into an acidic TiO 2 aqueous sol. Indeed, surface-mediated couples CH 3 COO À /NH 4 1 are formed within the slurry, which results in the reduction of the double layer repulsion between the particles; consequently, this induces TiO 2 particles to flocculate sufficiently to allow an increase in viscosity.…”

Titanium dioxide application in solar cells

“…39 Minoura e colaboradores desenvolveram uma pasta de partículas de TiO 2 com um precursor de Ti, que após aplicação em um substrato FTO e cristalização hidrotermal a 100 o C produziu filmes mesoporosos estáveis que renderam eficiências de até 4,2%. 40 Park e colaboradores desenvolveram um método usando uma pasta de TiO 2 altamente viscosa sem aglutinante e obteve eficiências de 2,5% para u eletrodo de μ de espessura seco a 150 o C. 41 Apesar das altas eficiências das CSSCs flexíveis obtidas nesses estudos prévios, os esforços de pesquisa foram confinados a células de tamanho pequeno que limitam o domínio do aplicativo.…”