Near-infrared Electroluminescent Devices Based On Rare Earth Complex Of NdQ And Colloidal PbS Quantum Dots

For the important applications in optical fiber communication, biological labeling and sensors et al., there has been a strong push to explore OLED with wavelength range between800and1600nm. Among the luminescent material for those devices, rare earth complex was found a valuable way of sharp narrow spectrum and high emission quantum efficiency. Also stable and solution-processable narrow band gap semiconductor quantum dots have attracted tremendous attentions recently. In this thesis, the NIR electroluminescent devices based on rare earth complexe of NdQ (neodymium tris-(8-hydroxyquinoline)) and PbS quantum dots are focused and developed.(1) By blending NdCl3in de-ionized water and8-hydroxyquinoline in methanol, the rare earth complex of NdQ was obtained and its luminescence mechanism was discussed. When was mixed with PVP completely, the emission intensity of NdQ was enhanced distinctly with the effective energy transfer from ligand to Nd3+. We owed the fact to the improved rigidity of the structure of NdQ.(2) With NdQ as active layer, a NIR OLED with structure of ITO/PEDOT:PSS/PVK/NdQ/Al was proposed. The EL spectrum shows three emission peaks at905,1064,1340nm which are correspond to Nd3+transitions of4F3/2â†'4I9/2,4F3/2â†'4I11/2,4F3/2â†'4I13/2respectively. The functional layers including PEDOT:PSS and PVK co-reduced hole injection barrier, thus improving the carrier balance. And high conductivity of PEDOT:PSS was benefit for the reduction of the series resistance and increased the working current of device. As the results, the device performance was improved obviously.(3) White organic light-emitting device with a structure of ITO/PVK:NPB/NdQ/Al was fabricated. The blue light from PVK:NPB layer and the orange light from NdQ layer were selected as the primary colors for satisfactory white emission.(4) PbS nanocrystals is regarded as a kind of important semiconductor materials in solar cells and optical detector. In this paper, a NIR light-emitting device with the structure of PbS QDs/Glass/ITO/PVK:NPB/Al are fabricated. With various size of PbS quantum dots layer as wavelength conversion film, the EL spectrum shows tunable emission peaks at900-1600nm in the NIR range under forward bias. PbS nanocrystals was also adopted as emission layer for the monolayer EL device. With voltage applied, continuously voltage-tunable EL spectra are observed which can be attributed to transition of lead ions.