Modification of Dye-Sensitized Solar Cells by SWCNT Composition as the Active Layer and Introducing TiO2@SiO2 Core–Shell Nanostructure for Light Scattering Layer: Toward Efficiency Enhancement

This study investigates the efficiency improvement of dye-sensitized solar cells (DSSCs) by removing issues in adsorbing dye molecules via enlarging active layer nanostructure. TiO2 nanoparticles (NPs) and the mixture of single-wall carbon nanotube (SWCNT) with TiO2 nanoparticles were used as the active layer in DSSC. Also, TiO2@SiO2 core–shell nanostructure was synthesized and used as a light scattering layer instead of the traditional TiO2 layers. In the TiO2 nanoparticle-based DSSCs, the number of exciton pairs is lower due to the lower space of nanostructures for adsorbing dye molecules, resulting in 3.56% efficiency. Using SWCNT in DSSCs increases the space of nanostructures for adsorbing dye molecules, boosting efficiency up to 5.10%. Moreover, measuring resistivity via four-point probe illustrates that using SWCNTs in nanostructures can cause a considerable decrease in resistivity up to
$0.589 \Omega $
/square. This phenomenon results in better current flow and higher efficiency in these cells. Via measuring UV–visible, it can be seen that mixing 0.04-wt.% SWCNT and TiO2 nanoparticles causes higher absorption than bare nanoparticle DSSCs. Also, UV–vis absorption spectra were applied to determine the optical bandgap of material via the modified Tauc method, which illustrates the reduction of bandgap up to 3.24 eV. Besides, particle sizes were calculated using Debye–Scherrer’s theory, which proves the field emission scanning electron microscopy (FESEM) images. Furthermore, the peaks in X-ray analysis proved the use of the different types of TiO2. Enhancement of structure is one way to improve solar cell characteristics such as efficiency and
${j}_{\text {sc}}$
. This enhancement can result in better charge collection, faster transportation of electrons, and a lower recombination rate that are the most significant issues of conventional solar cells.