Development of Non-Toxic Quantum Dots for Flexible Display Applications

Abstract

In order to achieve nanocrystals (NC) with stable and high photoluminescence (PL) and light harvesting efficiency (LHE), rare earth (RE) elements doped core/shell (CS) type semiconductors NC quantum dots (QDs) of group III-V elements were attempted with group II-VI element shell materials. An industrially adaptable low temperature ammine-ligands based process was chosen initially for the synthesis. Color control was achieved by tuning the size of the NCs. QDs having photoluminescence from infrared (IR) to blue were successfully synthesized. Quantum yield (QY) of these materials were attempted to increase by tuning the shell architecture. PL enhancement was observed with multiple shell growth indicating the inappropriate electronic (bandgap and band alignment) and surface (lattice mismatch) parameters for InP/ZnS binary CS system. A core/shell/shell (CSS) structure was attempted to overcome this lattice mismatch issue. Improvisation in efficiency was expected by converting them to upconverting nanoparticles (NPs). Doping with suitable IIB (Zn), VIIB (Mn) and RE elements (Ce, Er) can make them upconverting NPs free from environmental issue. Doping also could improve their thermal stability in display devices and increase the QY. Upconverting NPs are advantageous because in their hybrid photovoltaic devices they can produce high QY at IR region where solar spectrum has the highest photon flux density and also it is the region where most of the other materials fail. Doping these NCs with RE elements exhibited increase the optical efficiency. To improve the interparticle charge transport, surface modified versions of these nanoparticles were synthesized by replacing organic capping ligands on chemically synthesized nanocrystals with metal-free inorganic S2- and HS- ions which provided colloidal stability for the NCs in polar solvents.

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Document Details

Document Type
Technical Report
Publication Date
Nov 14, 2013
Accession Number
ADA588600

Entities

People

  • Kwang-sup Lee

Organizations

  • Hannam University

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Charge Carriers
  • Chemical Synthesis
  • Chemistry
  • Compound Semiconductors
  • Crystals
  • Electronics Industry
  • Electronics Laboratories
  • Materials Laboratories
  • Materials Processing
  • Materials Science
  • Materials Testing
  • Nanoparticles
  • Nanostructures
  • Optical Properties
  • Quantum Dots
  • Semiconductor Devices
  • Semiconductors

Fields of Study

  • Materials science

Readers

  • Organic Chemistry
  • Quantum Dot Semiconductor Device Photonics and Graphene Optoelectronic Materials and THz Physics.
  • Semiconductor Device Technology

Technology Areas

  • Biotechnology
  • Microelectronics
  • Quantum Computing