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Home > Fabrication and Characterization of Metal Halide Perovskite Based High Efficiency Solar Cells

Fabrication and Characterization of Metal Halide Perovskite Based High Efficiency Solar Cells

Thesis Info

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Author

Butt, Mira Tul Zubaida

Program

PhD

Institute

Lahore University of Management Sciences

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/11473/1/Mira%20tul%20zubaida%20butt%20chemistry%202019%20lums%20lhr.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726183665

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Silicon is still the dominant photovoltaic technology with over 90% share in the solar cell market. Prices of silicon solar cells have drastically reduced in the past few years which has led to its widespread adoption, but manufacturing of these cells requires huge capital and running cost and the processes involved are extremely time and energy intensive.For solar cells to become ubiquitous their cost needs to be significantly lowered. This can be done through new approaches which involve cheap materials and easy processing. Perovskite and dye sensitized solar cells have emerged as cost effective alternatives to the silicon solar cells due to their simple and easy processing and inexpensive constituents. Although perovskite solar cells have demonstrated a lab scale power conversion efficiency of over 22% but their ambient air synthesis and long-term stability against moisture and water remains a challenge to their commercial exploitation. Different approaches including a water resistive top coating on perovskite cells, substituting iodide with chloride ion and methyl group with formamidinium cation, constructing two-dimensional layered morphologies and morphology engineering using co-solvents and additives have been explored to address these issues. Among these approaches, additive engineering due to its ease of incorporation, simplicity and unprecedented control over the nature and architecture of substituents offers huge advantage over all the rest.This thesis presents results of the ambient-air synthesis and stability studies of perovskite solar cells prepared using additives with hydrophobic and hydrophilic substituents. To realize perovskite solar cells two-step approach was employed. Ethanolamine (EA), dibutylamine (DBA) and dibutylethanol amine (DBEA) were used as complexing agents to modify the nucleation and crystallization behavior of lead iodide during film formation. All three additives significantly enhanced solubility of lead iodide in dimethylformamide (DMF). Perovskite films prepared using EA, DBA and DBEA showed much improved surface coverages, larger and uniform grain sizes and much enhanced uniformities compared to pristine film, which exhibited gross phase separation. Power conversion efficiencies (PCE) of over 3%, 5% and 10.8% were obtained for EA, DBA and DBEA incorporated perovskites whereas pristine devices exhibited PEC values of under 1%.Photoluminescence (PL) spectroscopy confirms IV results that charge recombination is drastically reduced by the addition of these additives and the lowest recombination was observed for DBEA. Similar trend was observed for air-stability tests where DBEAincorporated devices showed highest stability (over 750 h) followed by DBA (over 500 h) and then EA (less than 200 h). Under same environmental conditions, pristine devices were found to be completely degraded within 150 h. Second part of this thesis reports on the efficiency enhancement of dye sensitized solar cells by directly depositing gold (Au) nanoparticles on the mesoporous titania scaffold before dye xii sensitization. Cells based on these photoanodes showed 9.48% efficiency compared to 6.1% for the reference cell, exhibiting an overall enhancement of 55% using only 0.11 wt% of Au, which is the lowest reported Au concentration for DSSCs in the literature to-date. We also report on the use of biomass-derived nitrogen-doped carbon aerogel as an effective alternative to conventional platinum based counter electrodes for dye sensitized solar cells. The nitrogen-doped carbon aerogel electrode, deposited from oleylamine mixture, was annealed at different temperatures and its impact on photovoltaic performance of these cells is investigated. I-V measurements confirm that the annealing temperature substantially enhances photovoltaic parameters of these devices. The power conversion efficiency of the solar cells from optimized nitrogen-doped carbon aerogel exhibited comparable efficiency to that of a cell fabricated using platinum-based counter electrode.
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کتنا تنہا تنہا سا ہے

کتنا تَنہا تَنہا سا ہے
دل کی بات نہیں کہتا ہے

یہ کیسی اُس کی عادت ہے
وہ تَنہا سب کچھ سہتا ہے

یاد مُجھے جب تیری آئے
دل ٹھنڈی آہیں بھَرتا ہے

رُوٹھ نہ جائے یار ہَمارا
ہوا چلے تو ، دل ڈرتا ہے

یہ خالی باتیں ہوتی ہیں
کون کسی بن اب مرتا ہے

اِک دن مجھ سے کہا تھا اُس نے
تُو مجھ کو اچھّا لگتا ہے

اِک دن میں نے خواب میں دیکھا
اُس نے مجھ کو مار دیا ہے

اب میں گھر لے آیا ہوں جو
میرؔ اُداسی چھوڑ گیا ہے

لوگ ندیم ندیم کہے ہیں
کون ندیم یہاں بنتا ہے

Exploring the Prevalence of Long-Covid and its Factors among Post-Covid Survivors of Karachi

Long COVID or post-COVID problems are long-term effects of COVID-19 infection that certain people who have contracted the virus can experience. This may result in having persistent symptoms for 3 months or more, such as those who had tiredness, malaise, changed smell and taste, dyspnea, and cognitive deficits three or more months after their initial COVID-19 diagnosis. However, some people may still have inferior work performance and a lower quality of life due to the long COVID episodes. From October 2021 to April 2022, cross-sectional research was conducted in Karachi, utilizing an electronic questionnaire to record sociodemographic data, current comorbidities, and previous episodes of acute COVID-19, post-COVID symptoms, and job performance among COVID survivors. The study's findings revealed that more than 35% of individuals surveyed claimed to have had COVID symptoms for six weeks or more, with approximately 20% to 30% of those reporting frequent coughing and appetite loss. Planning prevention, rehabilitation, and clinical treatment need an awareness of long-term COVID and its related components in order to maximize recovery and long-term COVID-19 outcomes.   DOI: https: //doi. Org/10.59564/amrj/01.01/007

Thermal, Kinetic and Morphological Studies of Available and Synthesized Pyrotechnic/Propellant Compositions and Their Ingredients

The work presented in this thesis is focused on the thermal, kinetic and morphological studies of various pyrotechnic/propellant compositions and their ingredients. A lot of research work has been carried out in the field of explosives; however, there is a lack of theoretical understanding and experimental work concerning the reaction kinetics of the pyrotechnics. The published work in the field of pyrotechnics presents some individual studies concerning different aspects such as thermal behaviour, kinetics and aging of the pyrotechnic compositions and their ingredients. The present work is a concerted effort to provide an insight into the thermal behaviour, kinetics, aging and morphological aspects of pyrotechnics/propellants. For this purpose, differential scanning calorimetry, differential thermal analysis and thermogravimetery have been mainly used along with scanning electron microscopy and X-ray diffraction for accomplishment of the present work. The comparison of thermal cum kinetic behaviour of five different oxidizers that are commonly used in various pyrotechnic/propellant compositions was carried out. Next, modified barium nitrate with micro porous structure was synthesized using three different vesicants to make it more reliable as a pyrotechnic oxidant. The pyrotechnic composition formulated with the modified oxidizer ignited at a lower temperature as compared to the one formulated with pure barium nitrate. The ignition behaviour of the vesicant modified barium nitrate has not been reported earlier to the best of our knowledge. Moreover, thermal and kinetic behaviour of ammonium perchlorate has been improved by catalyzing it with a small amount of nano magnesium oxide catalyst. The results indicate that the two distinct decomposition stages of the pure ammonium perchlorate merged with each other and reduced to a single stage. Furthermore, the reaction rate constant of the catalyzed AP also increased significantly. Pyrotechnics and propellants are inherently associated with some potential safety hazards and are therefore required to be investigated for their stability and decomposition kinetics. The thermal, kinetic and ignition behaviour of three pyrotechnic mixtures has been investigated in detail to elucidate the mechanism of ignition of these fuel oxidizer mixtures and to assess the thermal stability and reactivity. Temperature and humidity are amongst the important factors that influence the shelf life and ignition behaviour of the pyrotechnics. The effect of aging on two commonly used military pyrotechnics has been studied. The investigated compositions include SR-524 and SR-562 pyrotechnic compositions. The results indicate that aging of the pyrotechnic compositions at extreme conditions of temperature and humidity changed their thermal behaviour, kinetics, chemical composition and the surface features. The last part of the thesis describes in-depth kinetic analysis of three different versions of the composite solid propellant. Magnesium oxide and zinc oxide nano particles were used as catalysts to alter the performance of the composite propellant. The kinetic analysis has been carried out by Kissinger method, Flynn–Wall–Ozawa method, Friedman method and Kissinger-Akahira-Sunose method. The results indicate lowering of the decomposition temperatures in the catalyzed versions of propellant. The kinetic analysis showed increased reactivity of the catalyzed versions of the propellants. In a nut shell, the work presented in the thesis provided new insight into the thermal, kinetic and morphological aspects of propellants and pyrotechnics vis-a-vis their enhanced reactivity through incorporation of vesicants and nano catalysts, coupled with aging studies, to help design formulations for specific requirements wherever required.