| AVS 54th International Symposium | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM+NS-TuA |
| Session: | Semiconductor Nanostructures for Electronics and Optoelectronics II |
| Presenter: | J. Xu, Pennsylvania State University |
| Authors: | J. Xu, Pennsylvania State University Q. Sun, University of Dayton T. Zhu, Pennsylvania State University A. Wang, Ocean NanoTech LLC. Y. Li, Chinese Academy of Science, China |
| Correspondent: | Click to Email |
Recently, the development of low cost, solution-based synthesis of monodisperse, well characterized colloidal quantum dots (QDs) has generated a new class of material for the next generation-light emitting devices. Electroluminescent (EL) devices have been fabricated from thin films of colloidal QDs and exhibit saturated colors and broad wavelength coverage. Emission of EL devices can be easily tuned by varying the size and/or the material composition of nanoparticles during the synthesis process, while their chemical properties remain largely the same. Therefore, one device fabricating procedure can be adopted for different nanocrystals to produce emissions over a broad wavelength, covering the visible (0.4µm – 0.8µm) and NIR (0.8µm - 2.5µm) regions of the spectrum.In addition to the broad wavelength tunability, high fluorescence quantum yield and photochemical stability can be achieved by careful modification of the nanocrystal surface, and this may favor the efficiency of the EL device. All these unique properties have made semiconductor NQDs promising candidates for a broad range of applications, including flat panel display (FPD), light illumination, lightwave communication, and bio/chemical sensing. In this talk we present our work on the design and optimization of colloidal quantum dot (QD)-based light emitting diodes (LEDs) by tailoring the structure and layer thickness of the emissive QDs in the LED active region, the device configuration, as well as the electrode composition. The maximum brightness of red (?peak=619nm), orange (?peak=595nm), yellow (?peak=575nm), and green (?peak=526nm) QD-LEDs were measured to be 9064 cd/m2, 3200 cd/m2, 4470 cd/m2, and 3700 cd/m2, respectively, representing the highest brightness reported for QD-based EL devices. These devices were characterized with low turn-on voltages (3-4 V), high efficiency (1.1-2.7 Cd/A), and longer operation time at high brightness (t50%=300hrs at 1100 cd/m2) , indicative of the superior radiative properties and adequately-tailored carrier-injection and transport functions of the QD-active region in the LEDs.