Ag NP Enhanced EL In Organic Light Emission Diodes

Organic light-emitting diodes are widely used in plat display and lighting industry. Highly efficiency, luminescence and all solid, folded are the advantage that other light resource do not have. The disadvantages(thermally unstable, high cost) make those organics difficult to be widely used. So the high quality of transmittance conducting film, highly electron transfer layer and emitting material must be made.A high-quality transparent electrode of Zn O/Au/Zn O structure was obtained, with a resistivity as low as 6.89×10-4?·cm, a high transmittance of 80% in the visible frequency region and a thickness of only 50 nm. The underlying mechanism of conduction of Zn O/metal/Zn O multilayer structure film was analyzed by using quantum statistical theory and a theoretical model of resistivity was proposed. The resistivity of multilayers significantly relies on the work function and the thickness of interlayer metal. When the work function of metal is higher than that of Zn O the electron flows to the semiconductor much easier. The metal Au, work function 5.4e V, was be chosen as the middle layer. The experiment date is agrees well with theoretical result.Electron transmission improvement in organic light-emitting devices with Ag-Al co-doped Zn S has been demonstrated. The electroluminescence(EL) of device with co-doped Zn S electron transfer layer(ETL) is more than that of devices without ETL and the co-doped Zn S ETL device performs higher EL compared to pure Zn S ETL device. The using of co-doped Zn S can reduce the thickness of ETL from 40 nm to 8 nm and performs comparable efficiency and higher EL. According to the PL spectra studies and current density-voltage characters, the improved electron transmission is attributed to the introduction of impurity energy level and the increased concentration of electron.Ag nanoparticals(NPs) film was self-assembly formed on the surface of organic layer by controlling the evaporation rate of organic mamterials and silver. The absorb spectra show the strong Surface Plasmons(SPs) resonance effect from 334 to 610 nm, which overlap the exciton energy and the radiation emission of visible light. The electroluminescence(EL) enhancement of 5.5 times in organic light-emitting diodes has been demonstrated. The time-resolved photoluminescence spectroscope reveals that the EL enhancement is attributed to the energy of exciton transfer to SPs.