Integrated colloidal quantum dot smart optoelectronic devices for Internet of Things

Othman, Diyar 2024. Integrated colloidal quantum dot smart optoelectronic devices for Internet of Things. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

With the rapid growth of consumer electronics and the increase in technological innovations, the semiconductor industry has been one of the biggest in the world. However, traditionally used methods that require very high vacuum and temperatures increase the carbon footprint of the processes and in turn the industry. Today, many countries and companies have started initiatives to decrease their carbon footprint, aiming to limit the temperature increase accross the globe. Solution processing methods have been a hot research topic due to them offering alternative methods to the traditional methods to decrease their footprints. The main challenge of solution processing methods are reaching the required standards set by the traditional techniques. This project focused on using solution processing methods for their potential applications in Internet of Things devices. Out of the solution processed materials, colloidal quantum dots (CQDs) were the main focus due to their high quantum yield, optical tunability, stability and potential applications as both emitters and receivers. A simulation work has been done to improve the light extraction efficiency (LEE) of quantum dot light emitting diode (QLED) devices. It was found that a grating structure between the Indium Tin Oxide and glass interface along with a nanopillar structure on top of the glass can improve the LEE of QLEDs in different regions of the visible spectrum, and this can be tuned by changing the dimensions and the material of the nanopillars. The synthesis of InP CQDs were studied by using InCl3, InBr3 and InI3 as the indium precursor and tri(dimethylamino) phosphine as the phosphor precursor. The effect of different indium halides were compared as well as the reaction time and temperature. The synthesised QDs were then demonstrated as part of QLEDs. The inkjet printing of ZnO QDs and their use in QLEDs as ETL were studied. It was found that printed ZnO QD ETL QLEDs were comparable to the spin coated devices. In addition, patterned QLEDs were made that emit according to the ZnO printed pattern, indicating the possibility of printed devices and customisable patterns. A semiconducting copper sulfide was reported for the first time using the H2S exposure method, and its use as a photodetector was reported. Finally, an optical coupling demonstration was made between the fabricated QLEDs and the copper sulfide photodetector.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Colloidal quantum dots, QLED, Light extraction, LEE, Lumerical, InP, Inkjet Printing, IoT, Solution Processing, Copper Sulfide, Photodetector
Funders:	EPSRC
Date of First Compliant Deposit:	14 April 2025
Last Modified:	16 Apr 2025 08:01
URI:	https://orca.cardiff.ac.uk/id/eprint/177631

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