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  , Quantum Dot LEDs (QD-LEDs)
    Quantum dot (QD) is a nanometer-scale semiconductor crystallite which confines the electron-hole pair (exciton)
in all three dimensions. The electronic properties of these materials are intermediate between those of bulk semiconductors
and of discrete molecules.
 
  - Advantages of Quantum Dot for Application to Display
    One of the most important properties of Quantum Dots is the ability to tune their bandgap and therefore control
their light absorbance and emission. (from UV to IR region) Since quantum dots have narrow emission bandwidth
(FWHM~30nm), high colour-rendering index and broad colour gamut can be demonstrated. These great advantages
make QDs excellent candidates for future optoelectronics.

 
     
 
 
  - Efficient Inverted QLEDs
    We demonstrate highly bright and efficient inverted structure quantum dot (QD) based light-emitting diodes (QLEDs)
by using solution-processed ZnO nanoparticles as the electron injection/transport layer and by optimizing energy levels
with the organic hole transport layer. These results are signify a remarkable progress in QLEDs and offer a practicable
platform for the realization of QD-based full-color displays and lightings.
     
 
 
  - Systematical Analysis of QLEDs
    Remarkable progresses in the efficiency and stability of the QLED devices have been made, fundamental issues
from the materials perspective are still lingering. We probe the influence of shell thickness in QDs on the performance
of corresponding QLEDs. Also to figure out an incomplete understanding of the roles of extrinsic factors which hinder
improvement of LED performances, we address this problem with studies that correlate the excited state dynamics of
structurally engineered quantum dots with their emissive performance within LEDs.
     
 
 
  - Bright, low-voltage driven White QLED
    Among potential light-emitting applications, white-QLEDs have attracted keen attention as large-area plane light-sources
due to their simple device architecture, which is amenable to the cost-efficient solution-processing methods. We propose
very bright,low-voltage-driven white-QLEDs enabled by the direct exciton formation within QD active layers in an inverted
device architecture with organic and inorganic CTLs and their practicable applications toward traffic signals, display back-lights,
and flexible plane white-light sources have been exemplified.
     
 
 
  - Highly Efficient Cd-Free QLED
   We propose bright, efficient, and environmentally benign InP quantum dot (QD)-based light-emitting diodes (QLEDs)
through the direct charge carrier injection into QDs and the efficient radiative exciton recombination within QDs. We
believe that comprehensive scheme in designing device architecture and the structural formulation of QDs provides a
reasonable guideline for practical realization of environmentally benign, high-performance QLEDs in the future
     
 
 
  - Patterning Technology for QLED
   We introduce a soft contact QD-transplanting technique onto the vacuum-deposited small molecules without
pressure to pattern the QD layer. We examine the patternability of QDs by studying the surface properties of various
organic layers systematically. This pressure-free technique is essential for patterning and stacking the QDs onto
the soft organic layer to realize colloidal QD-based full-color displays and other optoelctronic applications.
     
 
 


2010 Organic Semiconductor Lab. Tel:880-9559 / Fax:872-6451