Electroluminescent Characteristics Of CdSe Colloidal Quantum Dots

Quantum Dots exibit promising potential in the applications of LED device serving as the active layer due to their unique luminescent properties. In order to introduce the CdSe QDs devices which are investigated in detail, the following aspects are described:the development and applications of LED and QDs LED; the mechanisms of photoluminescence and electroluminescence; the experimental apparatus used to characterize the LED device; the technological process of device fabrication and the analysis of the results.Electroluminescent (EL) devices with an ITO/ZnS/CdSe/ZnS/A1 structure were fabricated using chemically synthesized colloidal CdSe quantum dots (QDs) as its active layer. The measured size of the CdSe QDs is 4.3nm by a transmission electron microscope. Scanning electron microscope characterization reveals smooth surfaces of ZnS layers and Al electrodes. CdSe (111) and ZnS (111) diffraction peaks are observed in the X-ray diffraction patterns, verifying the incorporation of CdSe QDs and ZnS insulator materials in the devices. Room temperature photoluminescence (PL) spectra reveal that the CdSe QDs’emission peak is at 614nm. EL measurements at room temperature show a broad emission band ranging from 450 to 850 nm with a peak wavelength located at about 800 nm. Finally, the light emitting mechanism for the EL devices is proposed and the discrepancy between PL and EL spectra is interpreted.In the end, I spare some words to sum up my major work during my studying for the master’s degree, and looking forward to applications of QDs’LED.