In this presentation, efficient white polymer-light-emitting diodes have been fabricated with double emissive layers. The device structure consists of ITO/poly(ehtlenedioxythiophene): poly(styrene sulfonic acid) (PEDO...
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In this presentation, efficient white polymer-light-emitting diodes have been fabricated with double emissive layers. The device structure consists of ITO/poly(ehtlenedioxythiophene): poly(styrene sulfonic acid) (PEDOT: PSS)/poly(N-vinylcarbazole) (PVK) /phenyl-substituted PPV derivative (P-PPV)/poly(9, 9-dioctylfluorene) (PFO)/Ba/Al. By tuning the thickness of the emissive layers, white light was obtained. In EL spectra of the white light, the full width at half maximum (FWHM ) of the green band from P-PPV increased from 79 nm to 110 nm. Therefore, the EL spectra can cover the whole visible area. The 1931 CIE coordinates of the white light emission obtained were (0.31, 0.36). The maximum luminous efficiency is 3.8cd/A.
Performances enhancements of polymer light-emitting diode (PLED) were realized by inserting an ultrathin layer of NiO between the anode and hole injection layer. For PLED, there is a large energy barrier for hole inje...
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Performances enhancements of polymer light-emitting diode (PLED) were realized by inserting an ultrathin layer of NiO between the anode and hole injection layer. For PLED, there is a large energy barrier for hole injection with commonly used indium tin oxide (ITO) as anode. With a thin layer of NiO deposited on ITO, the energy barrier was decreased because of the higher work function of NiO than ITO, which facilitated hole injection. Therefore, the balance of electron and hole current was improved and also PLED performances. Experimental results also showed that the PLED performances were very sensitive to the thickness of NiO. Thick NiO layer led to the reduction of device current density, and therefore, poor PLED performances because NiO has a higher resistivity value than that of ITO. It turns out that 1 nm is the optimal thickness of NiO among 1, 2, 4 and 8 nm to produce high efficiency PLEDs. After the insertion of 1 nm NiO, the maximum electroluminescence intensity of PLED was almost doubled.
SnS and Ag films were deposited on glass sub-strates by vacuum thermal evaporation tech-nique successively, and then the films were annealed at different temperatures (0-300℃) in N2 atmosphere for 2h in order to obta...
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SnS and Ag films were deposited on glass sub-strates by vacuum thermal evaporation tech-nique successively, and then the films were annealed at different temperatures (0-300℃) in N2 atmosphere for 2h in order to obtain sil-ver-doped SnS ( SnS:Ag ) films. The phases of SnS:Ag films were analyzed by X-ray diffraction (XRD) system, which indicated that the films were polycrystalline SnS with orthogonal struc-ture, and the crystallites in the films were ex-clusively oriented along the(111)direction. With the increase of the annealing temperature, the carrier concentration and mobility of the films first rose and then dropped, whereas their re-sistivity and direct band gap Eg showed the contrary trend. At the annealing temperature of 260℃, the SnS:Ag films had the best properties: the direct bandgap was 1.3 eV, the carrier con-centration was up to 1.132 × 1017 cm-3, and the resistivity was about 3.1 Ωcm.
SnS∶Ag thin films were deposited on ITO glasses by pulse electro-deposition. By studying the effect of duty cycle on the properties of SnS∶Ag thin films, the optimum off-time(toff) is obtained to be 5 s, namely, the...
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SnS∶Ag thin films were deposited on ITO glasses by pulse electro-deposition. By studying the effect of duty cycle on the properties of SnS∶Ag thin films, the optimum off-time(toff) is obtained to be 5 s, namely, the optimal duty cycle is about 67%. The primary phase of SnS∶Ag films deposited on optimum parameters condition is SnS compound with good crystallization, and the films prefer to grow towards (111) plane. The films are dense, smooth and uniform with good microstructure, and the grains in the films are densely packed together, and their direct bandgap is about 1.40 eV. In addition, the bandgap of the films first rises and then drops with the increase of the duty cycle.
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