Enhance of TiO2 dopants incorporated reduced graphene oxide via RF magnetron sputtering for efficient dye-sensitised solar cells (original) (raw)
Related papers
2019
A study investigating the effects of titanium (Ti) atoms sputtered from different sources on substrate distance was attempted in order to effectively dope a reduced graphene oxide (rGO) thin film surface. Factors such as crystallinity, morphology, phase formation, light absorption, and surface chemical state of rGO-TiO 2 were investigated. As a result, functional groups or chemical states revealed the presence of Ti-O-C in rGO-TiO 2 na-nocomposite after the sputtering process. The titanium source from the target was of Ti 3+ species as determined using X-ray photoelectron spectroscopy (XPS). It was found that average sized Ti 3+ ions of around 59.4 nm were incorporated into the rGO nanosheet. A customized Dye-Sensitized Solar Cells (DSSCs) device was fabricated with the photo-anode consisting of sputtered rGO-TiO 2 nanocomposite. After optimization, the Ti target allocated with 10 cm-apart FTO glass-coated rGO nanosheet and 0.67 cm 2 active area exhibited an ideal PCE of 6.60%, which is remarkably higher than the usual 5 cm sputtering distance the sample (1.90%) had achieved.
Renewable solar energy is the key target to reduce fossil fuel consumption, minimize global warming issues, and indirectly minimizes erratic weather patterns. Herein, the authors synthesized an ultrathin reduced graphene oxide (rGO) nanosheet with~47 nm via an improved Hummer's method. The TiO 2 was deposited by RF sputtering onto an rGO nanosheet with a variation of temperature to enhance the photogenerated electron or charge carrier mobility transport for the photoanode component. The morphology, topologies, element composition, crystallinity as well as dye-sensitized solar cells' (DSSCs) performance were determined accordingly. Based on the results, FTIR spectra revealed presence of Ti-O-C bonds in every rGO-TiO 2 nanocomposite samples at 800 cm-1. Besides, XRD revealed that a broad peak of anatase TiO 2 was detected at~25.4 • after incorporation with the rGO. Furthermore, it was discovered that sputtering temperature of 120 • C created a desired power conversion energy (PCE) of 7.27% based on the J-V plot. Further increase of the sputtering temperature to 160 • C and 200 • C led to excessive TiO 2 growth on the rGO nanosheet, thus resulting in undesirable charge recombination formed at the photoanode in the DSSC device.
Reduced Graphene Oxide Decorated TiO2 for Improving Dye-Sensitized Solar Cells (DSSCs)
Current Nanoscience, 2019
In this comprehensive study, the influence of titanium dioxide (TiO2) dopants decorated on Reduced Graphene Oxide (rGO) via spin coating technique as an efficient photoelectrode in DSSCs was investigated in detail. This study aims to determine the optimum spinning duration for decorating TiO2 onto rGO nanosheet photoanode for high DSSCs performance. The rGO nanosheet was prepared using the electrodeposition method. A dropped of 0.2 wt% of TiO2 solution was absorbed using micro-pipette (0.1 μl) and continuously applied on FTOrGO surface with the rate of 0.1 μl/5s. The spinning duration was varied from 10 to 50 s, and resultant samples were labelled as Lt, where t= 10, 20, 30, 40 and 50s, respectively. The experimental results showed that TiO2 decorated rGO nanosheet photoanode for 30s spinning duration exhibited a maximum power conversion efficiency of 9.98% than that of pure rGO nanosheet photoanode (4.74%) under 150 W of xenon irradiation, which is about 2.1 times improvement in DSSCs performance. Ti4+ ion was decorated onto rGO nanosheet leading to the highest interactions with the O-H functional group or Ti4+ could react with the epoxide or phenolic groups in rGO forming the Ti-O-C bonds.
The Titanium Dioxide (TiO2)-reduced Graphene Oxide (rGO) were synthesized and doped at different concentration of 0.1wt%, 0.3wt% and 0.5wt% by varying the amount of rGO solution. The TiO2 nanoparticles were prepared via precipitation peptization method while rGO solution was prepared via chemical reduction and deposited by using Doctor Blade technique. The TiO2-rGO thin films samples were characterized by X-ray Diffraction (XRD) spectroscopy and Ultraviolet-visible spectroscopy (UV-Vis) for structural and optical properties while electrical properties were characterized by Keithley sourcemetre. It is observed that all of the TiO2-rGO samples possess the anatase TiO2 crystallinity phase which strongly appeared at (101), (004), (200) and (105) peaks and as the amount of rGO increases, the intensity of the peaks decreases. Meanwhile, 0.1wt% of TiO2-rGO has the highest absorbance wavelength with the lowest bandgap at 2.75 eV which due to formation of Ti-O-C bond. These were confirmed by...
The hybrid reduced graphene oxide (rGO) with titanium dioxide (TiO 2) species photoelectrodes forming a TiO 2 –rGO nanocomposite (TiO 2 –rGO NC) was prepared using a simple hydrothermal technique to enhance their visible light dye-sensitized solar cells (DSSCs) performances compared with the pure reduced graphene oxide (rGO) photoelectrodes. This study aims to determine the optimum loading content of TiO 2 species on the rGO photoelectrodes for improving their visible response in terms of conductivity as well as photoconversion efficiency. A low content of TiO 2 (0.3 wt%) species was successfully incorporated into the rGO photoelectrodes lattice and formed a Ti–O–C bond, which significantly maximized the photocurrent generation efficiency and promoted a charge separation by trapping the photo-induced electrons with 7.2%, which is relatively high compared to the pure rGO photoelectrodes (0.67%). However, the excess TiO 2 species of 0.4 and 0.5 wt% resulted in poor photoconversion efficiency performance attributed to the over photocatalytic reaction occurred leaving extra holes on the counter electrode. Herein, a novel hybrid formation between rGO and TiO 2 nanomaterials by using the one-step hydrothermal technique in order to improve the DSSCs performance which brought a better conductivity, higher photoconversion efficiency (0.67–7.20%), and lower recombination of rGO material was introduced.
Titanium (Ti) ion implantation approach was used in the present study to modify the reduced graphene oxide nanosheet (rGO NS) by incorporating the Ti 4+ ion (at various applied powers ranging from 50 to 250 W) onto the rGO NS to prepare photoanodes for Dye-Sensitized Solar Cell (DSSC). The surface morphologies, functional groups, optical properties and surface chemical states of the modified rGO based photoanode (rGO-TiO 2 nanocomposite (NC)) were studied. Fourier transform infrared (FTIR) spectra coupled with the elemental/chemical states in X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of Ti–O–C functional groups after the modification process. Besides, the average size of Ti ion was found to be 70–80 nm as incorporated with rGO NS. The spacing of anatase TiO 2 onto rGO NS were reported as 0.35 nm and 0.34 nm under HRTEM analysis, respectively. Experimental result implied that 150 W was the optimum applied power for the surface modification to take place ascribed to the lowest possibility for the recombination to occur and the smallest energy band gap. On top of that, at 150 W, the electron transfer rate was also found to be the highest due to the highest availability of the carbon-atom vacancy holes for Ti 4+ replacement. It was also discovered that the optimized power conversion efficiency (PCE) of 8.51% could be achieved in DSSC by implanting the Ti ion onto rGO NS-based photoanode using 150 W. Further increase of the applied power to 200 W or 250 W led to the undesirable recombination of the Ti ions and rGO NS due to the exceptional photocatalytic activity among N719 dye/rGO/TiO 2 interfaces which interfered the charge transportation at the KI electrolyte/N719 dye/rGO/TiO 2 interfaces.
Graphene and Graphene/TiO 2 Nanocomposites for Renewable Dye Sensitized Solar Cells
Renewable solar cell energy is a key target for sustainable energies development, which are inexhaustible and non-polluting for our energy system. To bring more solar related technologies to the point of commercial readiness and viability in terms of performance and cost, substantial research on the development of high efficient renewable dye-sensitized solar cell (DSSCs) device is necessary. Recent studies have indicated that graphene is a relatively novel material with unique properties that could apply in photoanode/counter electrode component as efficient electrode. In fact, the atom-thick 2D structure of graphene (rGO) provides an extraordinarily high conductivity, repeatability, productivity, and prolong lifetime to the related solar cell applications. Continuous efforts have been exerted to further improve the graphene textural and electronic properties by loading an optimum content of titanium dioxide (TiO 2) as an efficient photocatalyst in DSSCs. In this chapter, different synthesis strategies and characterization analyses for TiO 2-rGO nanocomposites (NC) as well as its prospects in DSSCs will be reviewed in detail.