Processing and Characterization of Mist deposited Patterned Quantum dot thin films

Open Access
Ramani, Shankarram
Graduate Program:
Electrical Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 18, 2009
Committee Members:
  • Jerzy Ruzyllo, Thesis Advisor
  • Jian Xu, Thesis Advisor
  • Quantum dots
  • Cadmium selenide
  • Mist deposition
  • Characterization
  • Display Applications
In this project, a study on the mist-deposited quantum dot films for novel inorganic display applications is carried out. For long, organic fluorescent dyes have been playing a vital role in different biological applications and also for electronic applications by building light emitting diodes. But over the past couple of decades, Quantum Dots (QDs) - semiconductor nanoparticles suspended in a colloidal solution, have attracted widespread attention and are believed to be the possible substitutes for the organic dyes. Cadmium selenide (CdSe) QDs are the most studied nanoparticles due to their direct bandgap and size-tunable wavelength properties spanning over the entire visible spectrum. These quantum dots are dispersed in toluene, an organic solvent. Conventionally, these quantum dots are deposited on the glass substrates by spin-coating or electro-phoretic deposition (similar to electroplating). But these methods do not provide a way to pattern these quantum dot films, because, the etch chemistries of QDs have not been fully developed yet. In this study, a technique of mist deposition is used to deposit the quantum dots on the masked glass and flexible substrates. Films thus obtained are characterized by means of their surface morphology (using AFM, SEM), and the QD-LEDs fabricated are investigated. Devices have been built and demonstrated using this deposition technique and the results prove possible applications in Nanophotonics and Optoelectronics. The results obtained indicate that a patterned relatively uniform layer of QDs is deposited, with some aggregations. This aggregation formation needs to be eliminated by optimizing and controlling the various deposition parameters.