Behaviour of printed electroluminiscent panel in accordance to order of layers

Abstract

In printing industry it is an important step to create more interactive designs to attract the customers. One of them is the utilization of electroluminescence. The properties of an electroluminescent device depend on the panel's structure, used materials, driving voltage and frequency. In this paper, an all printed electroluminescent panel is presented with different layer orders or number of layers. The panels' structures differ in the position and thickness of the dielectric layer. These different structures are causing changes in threshold voltage, highest obtainable luminance and durability of the panel. The behaviour of the panels and crystals of the active layer was inspected via spectrophotometry and optical microscopy in the range of voltages from 10 to 120 V at frequencies of 50 and 500 Hz driven by an AC power source. The results show that the panel structure with a single dielectric layer from only one side of the active layer, independently on the position (in front of or behind the active layer) has the highest luminance. It was revealed that the best durability is achieved with a double dielectric layer from both sides of the active layer. Occurrence of sparking is not acceptable, and thus as the most compliant panel structure is the panel with one dielectric layer from both sides of the active layer with luminance of more than 20 cd m–2. The heat arising from the sheet resistance of indium tin oxide showed a slight red shift in the emission spectra. A test on a ceramic heating table revealed that the shift is caused by heat.