Impacts of paste preparation methods on the porous TiO2 nanostructure properties and naturally dye-sensitized solar cells performance

Abstract

In the last two decades, researchers have attempted to use environmentally friendly pigments and porous nanostructures as sensitizers and semiconductors in dye-sensitized solar cells (DSSCs), respectively. In this study, the pigments were extracted from black plums (Syzygium cumini) to increase the biocompatibility of the DSSCs. The UV–vis spectroscopy of the extracted solution revealed the existence of anthocyanin pigments. The cyclic voltammetry measurement showed that the pigment energy levels were suitable for electron transfer to the TiO2 semiconductor, and the pigment electrochemical properties were also comparable with the commercial synthetic pigments. The dynamic light scattering experiment and zeta potential measurement illustrated that the size and electrostatic potential of the pigments were 0.3 nm and ±5 mV, respectively. These data confirmed the potential of the pigments for the diffusion into the porous structure of the TiO2 semiconductor and attraction as a shell layer on its surfaces. Besides, the TiO2 pastes were produced with seven different methods and characterized using XRD, SEM, and BET experiments. The results showed that the morphology, particle size, porosity, and surface area of the produced nanostructures were different in each method. Finally, the pastes were coated on the glass, sensitized with the extracted natural pigments, and used in the fabricated DSSCs. The efficiency of the cells was evaluated in the range of 0.027%–0.256% using the sun simulator technique. The results showed that the optimum particle size of the TiO2 semiconductor was around 25.6 nm which had been formed in the sixth method of the paste preparation.