Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

About: Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is a education organization based out in Topi, Pakistan. It is known for research contribution in the topics: Thin film & Quantum efficiency. The organization has 618 authors who have published 940 publications receiving 10674 citations.

Layer-by-Layer Titanium (IV) Chloride Treatment of TiO 2 Films to Improve Solar Energy Harvesting in Dye-Sensitized Solar Cells

Abstract: A layer-by-layer titanium (IV) chloride treatment was applied on different layers of TiO2 in dye-sensitized solar cells (DSSCs). The effects were analysed and compared with standard untreated devices. A significant increase in short-circuit current density (JSC) was observed by employing layer-by-layer TiCl4 treatment of TiO2 in DSSCs. This increase of JSC is attributed to the increased inter-particle connectivity and increase in TiO2 nanoparticle size, resulting in better electron transfer and a lower charge carrier recombination rate. The DSSC fabricated with layer-by-layer-treated TiO2 achieved power conversion efficiency of 8.3%, which is significantly higher than the 6.7% achieved for the DSSC fabricated without TiCl4 treatment. Electrochemical impedance spectroscopy (EIS) was performed to assess the better performance of the device fabricated with TiCl4 treatment. Atomic force microscopy and surface roughness were studied to visualize and statistically determine the function of TiCl4 treatment on different layers of TiO2. Transient photocurrent and transient photovoltage measurements were also performed to gain insight into interfacial charge carrier recombination.

A Weldless Approach for Thermocouple Fabrication Through Direct Ink Writing Technique

Abstract: Thermocouples are abundantly used for temperature measurement in various applications because of their availability and reliability. In this research two different materials, carbon a semiconductor and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS), an organic conductive polymer with silver as a common electrode were used to fabricate thermocouples through a weldless direct ink writing technique. Two different lengths were chosen for thermocouples to validate the effect of change in length on the performance of thermocouples. Each of the printed thermocouples is characterized and the sensitivity of thermocouples also known as the Seebeck coefficient are determined in a temperature range of up to 140°C. The Seebeck coefficients are found to be $\text{16.6-17}~\mu \text{V}/^{\circ }\text{C}$ for PEDOT:PSS/Silver thermocouples and $\text{15-17.8}~\mu \text{V}/^{\circ }\text{C}$ for carbon/silver thermocouples. These values are comparable to the recently reported numbers for the combination of the said materials. Furthermore, it was found that the Seebeck coefficient is not only material dependent but also influenced by the electrical properties of the printed thermocouples. Each type of printed thermocouple exhibits a stable and linear response towards the temperature change and is comparable to commercially available K-type thermocouple, however, the Seebeck coefficient reported is low when compared to K-type thermocouples due to material differences. Another key finding is the quick response and recovery time of the printed thermocouples as compared to sheath K-type thermocouples.

Microstructural characteristics of high-temperature oxidation in nickel-base superalloy

Abstract: High-temperature oxidation behavior of a nickel-base superalloy is examined using optical and scanning electron microscopical techniques. The morphology of the oxide layers developed is examined, and EDX microanalysis reveals diffusion of the elements across the oxide-metal interface. Evidence of internal oxidation is presented, and the role of structural defects is considered. The morphology of the oxide-metal interface formed in the specimens exposed in steam and air is examined to elucidate the mechanism of high-temperature oxidation.