Improved electron transportation of dye-sensitized solar cells using uniform mixed CNTs–TiO2 photoanode prepared by a new polymeric gel process

Abstract

A new facile strategy for fabrication of high surface area electrode in the form of mixtures of coated carbon nanotubes (CNTs) and TiO2 nanoparticles with various weight ratios is reported. The so-called polymeric gel process was used to deposit thick film containing uniform distribution of TiO2 nanoparticles and coated CNTs with high porosity by dip coating for dye-sensitized solar cells (DSSCs) applications. Based on simultaneous differential thermal analysis, the minimum annealing temperature to obtain inorganic- and organic-free films was determined at 500 °C. X-ray diffraction analysis revealed that deposited films were composed of primary nanoparticles with crystallite size in the range 21–45 nm. Field emission scanning electron microscope images showed that deposited films had porous morphology containing uniform spherical particles with diameter around 2.5 μm and coated CNTs with TiO2 nanoparticles (TNTs). The spherical particles were composed of small nanoparticles (~60 nm), improving light scattering and dye loading of the DSSC. Moreover, TNTs were uniformly incorporated into the electrodes, improving electron transportation. X-ray photoelectron spectroscopy was presented as an obvious proof for the inclusion of CNTs into the TiO2 matrix. Ultraviolet–visible spectroscopy showed that CNT introduction enhanced the visible light absorption of photoanode by shifting the absorption onset to visible light region. An enhancement of power conversion efficiency (PCE) from 6.53 % for pure TiO2 to 7.38 % for CNT–TiO2 electrode containing 0.025 wt% CNTs was achieved. This well-incorporated study would present an intellectual development in the fabrication of low-cost CNT consolidated DSSCs with high PCE.