The cadmium selenite (CdSe) quantum dots (QDs) have promising applications in display technology since
its luminescence wavelength can be tuned precisely from blue to red by changing the diameter of the core from
2.0 to 7.0 nm. A self-assembled monolayer of QDs, sandwiched between two organic thin films is necessary to
isolate the luminescence processes from charge conduction. The use of QDs for device technology, one of the
fundamental issues is how to distribute QDs uniformly on patterned surfaces with precise control of density. In
this study, we demonstrate that uniform distribution of QDs with controllable density can be achieved using the
conventional spin-coating method. We have fabricated high efficient QD-OLED by spin-coating method. The
estimated QDs threshold concentration was found ~ 9x1011 cm-2 for the best performance of QD-OLED. The
AFM morphological studies of the hybrid device showed the formation of a disordered QD film as a result of
the aggregation of CdSe/ZnS QDs upon phase segregation. The analysis of electroluminescence (EL) and
photoluminescence (PL) performance of OLED showed that precise control of the QD concentration is
necessary to maximize the coverage of QDs on organic surface which is an important factor in color tuning. The
peak energies of the EL and PL showed only small spectral shifts and no significant dependence on the QDconcentration.
The QD emission was increased about three times by annealing of QD-OLED.
High power InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition (MOCVD) were fabricated with pulsed anodic oxidation. A maximum light power output of 304 mW was obtained from a 10-μm stripe width uncoated laser diode in continuous wave (CW) mode at room temperature. The characteristic temperature of the lasers was 138 K.
We have studied the carrier transport properties of amorphous organic material tris (8-hydroxyquinoline) aluminum (Alq3) for Al, LiF/Al, NaCl/Al, KBr/Al cathodes and ITO and ITO/HTL anodes at room temperature. The investigation was made by the current - voltage, luminescence - current characteristic measurements. The current density increases by several orders for LiF/Al and NaCl/Al cathodes over that of Al at a given bias voltage. The electron injection processes at the metal/organic contact dominate the current - voltage characteristics. The carrier injection seems to be limited by the charge hopping of interfacial molecular sites. We have also developed a process method for the preparation of anodic indium-tin-oxide (ITO) surface for high efficient organic light emitting diodes (OLEDs). X-ray photoelectron spectroscopy (XPS) was used to measure atomic concentration of each element In, Sn, O and C on treated ITO surface. Scanning electron microscopy and atomic force microscopy were used to scan the surface profiles of ITO. The OLED performance considerably improved by the ITO surface treatments as well as by ITO/HTL anode due to the reduction of holes injection barrier between ITO and Alq3 interface.