The focus of this research is to improve the performance of dye-sensitized solar cells (DSSC) through the adoption of high-quality FTO thin films and incorporation of graphene with DSSC photoanode to enhance its electrical transport. In this research, nanostructured FTO films were first grown with homemade Streaming Process for Electroless and Electrochemical Deposition technology (SPEED) using Tin (II) chloride dihydrate and ammonium fluoride and other chemical formulations. The FTO structural property was measured by X-ray diffraction (XRD); the films’ optical property was determined with transmittance spectra to curve over the wavelength range of 200-1000 nm measured with a spectrophotometer while scanning electron microscope (SEM) was used to determine the morphological properties of the samples. The electrical transport was evaluated by Hall Effect measurements at room temperature with a four-point probe. The FTO samples with the best structural, optical and electrical properties were employed as electrodes and counter electrodes of DSSC along with titanium dioxide. Thus, effect of graphene on the efficiency of DSSC was investigated. It was shown that a graphene-based DSSC showed an efficiency of 7.98% which is slightly higher than that of DSSC prototype without graphene (6.02%). The higher efficiency obtained with graphene can be credited to the ultrahigh surface area and thermal conductivity of graphene which tend to enhance the charge mobility and photovoltaic performance of DSSC. More research is however required to determine the exact amount of graphene that could achieve optimal DSSC performance. Further studies will also offer an adequate clarification for starting point of the better incorporation of graphene in DSSCs.

This work examines the impact of the nozzle-substrate distance (NSD) on the structural, optical and electrical properties of fluorine-doped tin oxide (FTO) thin films. The films were grown by spray pyrolysis with the chemical formulation of “Streaming Process for Electroless and Electrochemical Deposition technology” (SPEED) technique. The characterization technique such as XRD, SEM, UV-spectrophotometry and Hall Effect measurement were employed for studying the structural, optical and electrical properties of the FTO films at various NSD. The NSD was varied from 25-32cm amid the experiment. All FTO films are polycrystalline, tetragonal crystal structure with strong orientation along the (211) reflection. SEM properties study demonstrated slight reliance on NSD and have uniform films which are a disciple to substrate at NSD of 27 and 30 cm, however, crumbled at 25cm and 32cm NSD. They likewise displayed a mud-look like morphology and smooth white appearance. The average optical transmittance of all films is over 80% in the noticeable at UV range. The band gap investigation demonstrates the average value of 3.5eV and the resistivity was found to diminish with increasing NSD at 30 cm. Both mobility and carrier concentration of the FTO films follow a similar trend. The average figure of merit of 4.98 was obtained which is an improvement based on our previous results. The FTO samples grown at 27 and 30 cm NSD in this work are best FTO samples and hence could serve as a promising candidate in dye sensitized solar cells. Therfore, graphene has been employed in different concentrations in our ongoing FTO optimization research so as to further improve on the FTO’s figure of merit.

Influence of water concentration on the properties of fluorine-doped tin oxide (FTO) thin films was systematically studied in this work. Home made SISOM’s SPEED techniques and its chemical formulation was employed to grow the FTO on quartz substrate. Water concentration in the precursor solution was varied from 0, 0.5, 1.0 and 1.5 mol %. The structural, optical, and electrical properties of the films were studied under these deposition conditions. The results show that the properties of the films varied significantly with water concentration. Scanning electron microscopy (SEM) revealed FTO films whose grain size and uniformity increases significantly with increase in water concentration. The structure of the films was measured by X-ray diffraction (XRD) measurement. It shows polycrystalline films with (110), (101), (200), (211) and (220) orientation; the strength increases as water concentration increases. The optical transmission was determined by UV-Vis spectroscopy at 380–780 nm UV-VIS regions. The optical transmittance varies with water concentration with an average of 84%. The electrical property, measured by Hall Effect revealed n-type semiconductor. The films have the following properties: resistivity, 15 × 10^-4Ω cm; carrier concentration, 18.7 × 10¹⁹ cm^-3 and mobility of 21.86 cm² V^-1 s^-1. The average figure of merit, φ of the FTO film is 1.25. Optimum deposition condition was established after series of experiments and was found to be 1.5% water concentration at 460^oC substrate temperature. The FTO films deposited in this work could be a promising replacement to indium tin oxide (ITO) especially in dye-sensitized solar cells.