Zinc Sulfide D-C Electroluminescent Displays

Abstract

A study of the materials preparation of zinc sulfide powders activated by manganese and copper has yielded direct‐current electroluminescent cells with considerably improved performance. Investigation of the forming process has led to new cell configurations which are described. Some low‐voltage characteristics are illustrated, 0.5 ft‐L being obtained at 20V. The main problem of deterioration is discussed.

Forming of powder DC electroluminescent displays. I. Characterisation and effects of gaseous environment

“…Finally, we note that the confusion which exists in the literature about what happens to the surface Cu on the ZnS particles in the formed layer has not been resolved, but our experiments suggest strongly that the view originally propounded by Vecht et al [2,3], that Cu diffused into the phosphor, is probably more correct than the currently held view that it electro-migrates towards the cathode.…”

“…However, it was not possible to distinguish between copper depletion by diffusion into the particles or by surface migration towards the cathode because the Cu detection limit of the instrument was 0.5 at.%, which was significantly greater than the total Cu concentration of 0.32 at.% Information on Cu depletion in the formed zone was obtained from electron probe microanalysis (EPMA). To avoid interference from the ITO and the glass, a gap cell configuration [2] was used; a Cu-coated phosphor, dispersed in organic binder, was spread between two electrodes on an insulating base. Forming occurred in a plane between the electrodes, intersecting the free surface so the formed layer could be examined in cross section.…”

Applications for Metal−Organic Frameworks (MOFs) as Quantum Dot Semiconductors

“…The basic structure of an inorganic electroluminescence (EL) device is similar to that of the photovoltaic cell described above. It consists of a transparent conductive ITO electrode and a metallic counter electrode sandwiching a thin (submillimetric) film of a photoactive material (generally referred to as a phosphor). , In more complex EL cells, layers of additional components, such as dielectric or moisture-protective layers, can also be included to enhance the intensity, durability, and efficiency of the device . Most phosphors have in common that they are (doped) semiconductors, with a filled valence band and an empty conduction band.…”

Forming of powder DC electroluminescent displays. II. Mechanisms and implications for maintenance

“…Most of the applied voltage (about 100 V) is dropped over a narrow region (about 1 pm wide) leading to local fields of about lo7 to 10' V m-' that are high enough to produce hot electrons that impact excite the Mn-ion centres responsible for the 590 nm yellow light emission. This behaviour is well known [2] and forming is a key point of the production of the DCEL displays manufactured by Phosphor Products Co. Ltd of Poole, UK. A physical model that can be used to explain this change was put forward by Vecht and co-workers [2] and has subsequently been elaborated by others [3, 41. Our recent observations [l] have led us to reconsider the processes occurring during forming and one t See the footnote to the first page of the preceding paper.…”