Savisha Mahalingam

Structural, Morphological, and Electron Transport Studies of Annealing Dependent In2O3 Dye-Sensitized Solar Cell

Indium oxide (In2O3) thin films annealed at various annealing temperatures were prepared by using spin-coating method for dye-sensitized solar cells (DSSCs). The objective of this research is to enhance the photovoltaic conversion efficiency in In2O3 thin films by finding the optimum annealing temperature and also to study the reason for high and low performance in the annealed In2O3 thin films. The structural and morphological characteristics of In2O3 thin films were studied via XRD patterns, atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), EDX sampling, and transmission electron microscopy (TEM). The annealing treatment modified the nanostructures of the In2O3 thin films viewed through FESEM images. The In2O3-450°C-based DSSC exhibited better photovoltaic performance than the other annealed thin films of 1.54%. The electron properties were studied by electrochemical impedance spectroscopy (EIS) unit. The In2O3-450°C thin films provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSC.

Optical, morphology and electrical properties of In2O3 incorporating acid-treated single-walled carbon nanotubes based DSSC

This study focuses on the influence of an acid treatment process of single-walled carbon nanotubes (SWCNTs) in In2O3-based dye-sensitized solar cells (DSSCs). Pure In2O3, In2O3-SWCNTs with acid treatment and In2O3-SWCNTs without acid treatment were prepared using the sol–gel method via a spin coating technique annealed at 450 °C. The optical, morphology and electrical properties of the photoanodes were characterized by means of UV–Vis analysis, atomic force microscopy and field-emission scanning electron microscopy, and J–V curve measurements, respectively. The optical band gap obtained through UV–Vis analysis showed that the acid treatment process modified the band gap of the photoanode, which enhances the V oc of the DSSCs. In addition, In2O3-SWCNTs with acid treatment possess a porous structure that improves the power conversion efficiency (PCE) of the DSSCs. In addition, the diameter of acid-treated SWCNTs was reduced compared to pristine SWCNTs. In2O3-SWCNTs with acid treatment exhibited the highest PCE of 1.40% with J sc of 7.6 mA cm−2, V oc of 0.51 V, and fill factor of 0.36. The increment in V oc is due to the higher band gap obtained through the UV–Vis absorption spectrum. Moreover, In2O3-SWCNTs with acid treatment has a higher electron lifetime with a higher effective diffusion coefficient that slows down the recombination rate and speeds up the electron transport process.

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.

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.

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.