Photoluminescent Properties Of Ag/ZnO Hybrid Mampstruture And Quantum Dots LEDs

Quantum dots (QDs) have found broad applications in consumer electronics. The research and development of QDs technique are very active and often hit headlines, which is due to the outstanding characteristics of QDs, such as large quantum-size effect, high opto-chemical stability, narrow and symmetrical emission spectrum, wide spectral tunability, large lifetime, etc.In recent years, the optical properties of the QDs have been intensively studied, because of the application in luminescent materials and devices, like quantum dots light emitting diodes (QLEDs) and solar cells. In this work, we carried out a systematic study of photoluminescence (PL) and electroluminescence (EL) properties in term of QDs.PL characterization:aqueous phase Ag nanoparticles (NPs) and ZnO QDs were prepared by chemosynthesis, respectively. With the increase of reaction temperatrue, the size of Ag NPs becomes larger. Meanwhile, the spherical shape of Ag NPs gradually evolves into triangular nanoplates. Analogously, with the reaction time increasing, the size of ZnO QDs gets larger, but not as much as that of Ag NPs.The Ag/ZnO composite nanostructure consists of Ag NPs and ZnO QDs which were spinned coated on the silicon wafer successively. The PL results show that Ag/ZnO hybrid nanostructure exhibits stronger UV emission and weaker visible emission compared to those of the pure ZnO QDs, which is attributed to the distinct surface plasmon resonance (SPR) effect and energy transfer between Ag NPs and ZnO QDs.EL characterization:In this thesis, the QLEDs are fabricated adopting the hybrid structure of ITO/NiO/QDs/PMMA/ZnO QDs/Ag, in which ZnO QDs act as the electron transport layer (ETL). The EL properties of QLEDs with CdZnS/ZnS core-shell QDs and CuInZnS QDs active layers were studied, respectively. The spin coating of the ZnO QDs ETL can avoid the damage to the QDs active layer which is suffered in the magnetron sputtering growth of corresponding ETL, lowering the turn-on voltage and improving the luminescent efficiency. Moreover, it can simplify the fabrication process and reduce the cost.