Mohd Zikri Razali

Enhancement of dye-sensitized solar cell efficiency using carbon nanotube/TiO2 nanocomposite thin films fabricated at various annealing temperatures

To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes (CNTs) were added to TiO2 gel-like solution. Modified acid-catalyzed sol-gel method was used with the doctor blade coating technique to obtain thin films of CNT/TiO2 nanocomposite photoanode. CNT/TiO2 paste was applied onto the conductive glass to generate a 0.25 cm2 active area which was later annealed at 350°C, 450°C, and 550°C for 60 min. Characterization of the CNT/TiO2 paste was performed using x-ray diffraction. Results showed that the crystalline phase of the particles was anatase. The micrograph obtained using field emission scanning electron microscopy demonstrated that the pastes are highly porous. Brunauer-Emmett-Teller analysis was performed to determine the CNT/TiO2 surface area and particle size. The DSSC with the CNT/TiO2 photoanodes annealed at 550°C showed the highest incident photon-to-charge carrier efficiency value of 0.95% compared with the DSSCs with photoanodes annealed at 350°C and 450°C (0.70% and 0.83%, respectively). The observed efficiencies of the DSSCs with CNT/TiO2 photoanode annealed at the three different temperatures were 2.62%, 2.65%, and 3.13%. The electrochemical impedance spectroscopy analysis showed that the DSSCs with photoanodes developed using the highest annealing temperature (550°C) have higher electron lifetime of 70.423 ms and lower effective recombination rate of 1.42 × 10−2 s−1, thereby improving the performance of CNT/TiO2 DSSCs.

Platinum-Incorporating Graphene Counter Electrode for In2O3-Based DSSC with Various Annealing Temperatures

Development of platinum incorporating graphene (pt/graphene) thin films was prepared by sol-gel method via chemical bath deposition (CBD). Indium oxide (In2O3) as photoanode and pt/graphene as counter electrode is used to analyse the characteristics and performance of dye-sensitized solar cell (DSSC). Different annealing temperatures of 200 oC, 250 oC and 300 oC were proposed for the counter electrode in this study. The changes in the structural properties were analyzed by means of X-ray Diffraction (XRD) and atomic force microscopy (AFM) analysis. AFM results indicated very rough surface area of graphene sheet where roughness values decreased linearly from 0.65 μm to 0.18 μm by an increment in annealing temperature. The In2O3-based DSSC exhibited good photovoltaic performance with power conversion efficiency (η), photocurrent density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 0.47 %, 5.46 mA cm-2, 0.54 V and 0.36 respectively. The obtained structural and photovoltaic performance analysis was proposed as a suitable benchmark for pt/graphene counter electrode with In2O3-based DSSC.

Manipulation of MWCNT Concentration in MWCNT/TiO2 Nanocomposite Thin Films for Dye-Sensitized Solar Cell

Dye-sensitized solar cell (DSSC) using multiwalled carbon nanotube/titanium dioxide (MWCNT/TiO2) was successfully synthesized using sol-gel method. In this method, it has been performed under various acid treatments MWCNT concentration level at (a) 0.00 g, (b) 0.01 g, (c) 0.02 g, and (d) 0.03 g. Atomic force microscopy (AFM) was used to study surface roughness of the MWCNT/TiO2 thin films. The average roughness results for 0.00 g, 0.01 g, 0.02 g, and 0.03 g were 10.995, 18.308, 24.322, and 25.723 nm, respectively. High resolution transmission electron microscopy (HR-TEM) analysis showned the inner structural design of the MWCNT/TiO2 particles. The TiO2 nanoparticles covered almost all the area of MWCNT particles. Field emission scanning electron microscopy (FESEM) gave the morphological surface structure of the thin films. The thin films formed in good distribution with homogenous design. The DSSC with MWCNT/TiO2 electrode containing 0.03 g MWCNT were resulted in the highest efficiency of 2.80% with short-circuit current density of 9.42 mA/cm2 and open-circuit voltage of 0.65 V.

Natural dye extracted from Pandannus amaryllifolius leaves as sensitizer in fabrication of dye-sensitized solar cells

1 Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia 2 Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor, Malaysia 3 Fuel Cell Institute, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor, Malaysia 4 Department of Biology, College of Education for Pure Sciences/Ibn Al-Haitham, University of Baghdad, Baghdad, Iraq * Email address: mamash73@yahoo.com

Morphological Effect of CNT/TiO2 Nanocomposite Photoelectrodes Dye-Sensitized Solar Cell on Photovoltaic Performance with Various Annealing Temperatures

This research focused on the fabrication of dye-sensitized solar cell based on a photoanode of carbon nanotube/titanium dioxide (CNT/TiO2) nanocomposite photoanode synthesized through acid-catalyzed sol-gel method. The results show the improvement of the chemical and electrical properties of the solar cells annealed at different temperatures. The CNT/TiO2 colloidal solution was synthesized using titanium tetraisopropoxide and CNT/2-propanol solution. The thin films were doctor-bladed on a fluorine tin oxide glass before being annealed at 550, 650, and 750°C. The field emission scanning electron microscopy morphological images show that the thin films were homogenously distributed and maintained their spherical structures. The X-ray diffraction patterns show that the films consisted of anatase and rutile phases with large crystallite sizes due to temperature increment. The atomic force microscopy analysis presents the thin film roughness in terms of root mean square roughness. The photovoltaic performance was analyzed using IV curve and electrochemical impedance spectroscopy (EIS). The thin films annealed at 750°C had the highest energy conversion efficiency at 5.23%. The EIS analysis estimated the values of the effective electron lifetime (), effective electron diffusion coefficient, effective electron diffusion (), and effective recombination rate constant (). A large , small , and longer can improve photovoltaic performance efficiency.

Structural, Morphological, Photovoltaic and Electron Transport Properties of ZnO Based DSSC with Different Concentrations of MWCNTs

This study highlights the structural, morphological, photovoltaic and electron transport properties of zinc oxide-multi-walled carbon nanotubes (ZnO-MWCNTs) based dye-sensitized solar cell (DSSC) prepared at different concentrations of 0.0, 0.1, 0.3 and 0.5 wt.%. The ZnO-MWCNTs thin films were prepared by a chemical bath deposition method. X-ray diffraction (XRD) analysis proved the formation of hexagonal wurtzite of the samples. The crystallite sizes, D of ZnO-MWCNTs was measured varies from 21 nm to 11 nm. The oat-like ZnO nanoflakes structure and the presence of MWCNTs were captured by field-emission scanning electron microscopy (FESEM) analysis. Transmission electron microscopy (TEM) analysis measured the inner (~6.81 nm) and outer (~28.31 nm) diameter of MWCNTs. The optimum concentration of 0.1 wt.% MWCNTs produced the highest photocurrent density, Jsc of 13.5 mA/cm2, open-circuit voltage, Voc of 0.149 V, fill factor, FF of 0.406 and power conversion efficiency, PCE of 0.817 %. Optimum doping of 0.1 wt.% MWCNTs generated short electron lifetime, τeff of 0.67 ms, low effective electron chemical diffusion coefficient, Deff of 9.5 x 10-8 cm2 s-1 and higher electron recombination rate, keff of 1497.48 s-1. The addition of MWCNTs has influenced the structural, morphological, photovoltaic and electron transport properties of ZnO-MWCNTs based DSSC.

Effect of Heat Treatment on CNT/TiO2 Photoelectrode for Dye-Sensitized Solar Cells Application

In this research, the CNT/TiO2 nanocomposite solution was prepared using sol-gel method process. Definite amounts of CNT (0.06 g) were sonicated in 30 ml anhydrate 2-propanol. The measured quantities of Titanium (IV) Tetraisopropoxide (TTIP) – 5 ml were introduced into the CNT/2-propanol solution. The CNT/TiO2 paste was doctor-bladed onto the FTO glass and consequently annealed at 250 °C, 350 °C and 450 °C for 30 min. The effect of annealing temperatures on the CNT/TiO2 thin films was discussed. The CNT/TiO2 thin films were characterized for morphological and electrical performance by Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), Incident Photon to Charge Carrier Efficiency (IPCE) and IV-Curve Efficiency analysis. The XRD patterns show the thin films major peak at (101) with average anatase phase crystallite size. The CNT/TiO2 thin films morphological structure composed of compressed and porous distributed composition. The crystal structures were changed upon increasing the annealing temperature. The IV measurement shows that the dye-sensitized solar cell (DSSC) at 450 °C produced highest photoelectric conversion efficiency (η) with 3.88 %. IPCE graph shows the solar cell absorb light within the UV spectrum region. It is revealed that annealing temperature has influence toward photovoltaic performance of the assembled DSSC.

Preparation of Titanium Dioxide Paste for Dye Sensitized Solar Cells (DSSCs)

A dye-sensitized solar cell based on TiO2 electrode was prepared by mixing the TiO2 nanopowder and TiCl4 aqueous solution, in which the mixture was used as the paste to deposit onto the fluorine doped tin oxide (FTO) coated glass substrates by screen-printing method. DSSC were created after a rinse of TiO2 electrode with acetonitrile to remove excess dye molecules. The synthesis and characterization of the TiO2 paste was figured out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The TiO2 layer is homogeneous and composed of anatase and rutile particles. The photocurrent-voltage of the cell was fabricated and the comparison dye was made by using the eosin Y and N719. The sample that use N719 dye showed the better result which is generating a short-circuit photocurrent density of 0.0299 mA/cm2, an open-circuit voltage of 0.713 V, and the energy conversion efficiency was 0.08926 %.

Influence of Graphene (0.01 wt. %) on Structural, Morphological and Photovoltaic Properties of TiO2-Based DSSC Using Electrolyte Gel

Titanium dioxide (TiO2) based dye-sensitized solar cells (DSSCs) doped with reduced graphene oxide, rGO also known as graphene were fabricated at concentrations of 0.01 wt.% . The performance of TiO2/graphene based DSSC and TiO2 based DSSC were studied using electrolytes; PAN-based gel electrolyte. The thin films were characterized using several characterizations such as scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and current-voltage (I-V) measurement. The micrograph images obtained by SEM demonstrated that the thin films are highly porous. The XRD characterization showed that the crystalline particle of thin films is an anatase state and high percentage of carbon composition can be determined using EDX analysis. Through I-V characteristic, the current density Jsc, open circuit-voltage Voc, fill-factor FF, and efficiency η of the TiO2-based DSSC were 0.196 mA/cm2, 0.44 V, 0.496 and 0.043% respectively. I-V characteristic showed an increase in values for rGO/TiO2 based DSSC such as Jsc = 1.177 mA/cm2, Voc = 0.66 V, FF = 0.656 and η = 0.509%. The addition of rGO concentration has improved the efficiency of DSSC while the use of electrolyte gel can sustain the stability of the cell.

Characterization of carbon nanotube/titanium dioxide acid treatment nanocomposite structure using sol-gel method

Titanium dioxide had been noticed thoroughly for their superiorities over conventional p-n junction devices, such as low cost and slighter toxic in construction. In this research, we present and study the preparation of Carbon Nanotube/TiO2 acid treatment nanocomposite by the alteration of acid-catalyzed sol-gel method. The CNT/TiO2 nanocomposite powder was acid treatment in NaOH solution and directed on FTO glass substrates. The CNT/TiO2 paste was doctor blade onto the substrate plate to form a 1.0 cm2 active region and later on annealed at 550°C, 650°C and 750°C for 30 min. The characterization of the TiO2 adhesive was carried out by X-ray diffraction (XRD) and the results indicate that the particles of CNT/TiO2 are in rutile form not in anatase structure. The micrographs of scanning electron microscopy (SEM) images prove that the thin film pastes have high porosity and the Brunauer Emmett Teller (BET) result show the surface area, pore volume and pore size for the CNT/TiO2 thin film.