Fabrication of Organic/Inorganic LED device using nanocrystal quantum dots as active layer

Recently, researches on nanocrystal quantum dot-based LEDs (NQD-based LEDs) have dramatically increased due to their characteristics resulting in pure and saturated colors with a narrow bandwidth. More importantly, colors can be easily tuned by varying the size or the composition of NQDs, and high quantum yields (QY) of NQDs can increase the efficiency greatly. In spite of high fluorescence QY of NQDs, the reported efficiency of QD-LEDs is still low because the carrier transport is not efficient in the fabricated device. We report efficient electroluminescence in quantum dot-based LEDs by enhancing the electronic coupling of NQDs. 2D array of NQDs formed by spin-coating showed enhanced electrical conductivity. They are incorporated into the light emitting device as an active layer. Current-voltage characteristic and electroluminescent spectra of the device are measured. Electroluminescence efficiency of the device is improved, resulting from the facilitated carrier transport between layers by electronic coupling of NQDs.

I. Introduction

Recently, nanocrystal quantum dots (NQD), II-VI semiconductor compounds, are one the most actively studied components of modern nano science and progress diverse research about electronic device such as FPD (flat panel display) and LED (light-emitting diode) field. The high degree of control over their size and shape makes it possible to accurately tune their optoelectronic properties through quantum confinement [1].