Lighting Tiles

Abstract

We describe a lighting tile having a substrate bearing an electrode structure, the electrode structure comprising: a plurality of electrically conductive tracks disposed over said substrate; and an electrical connection region connecting to said plurality of tracks; wherein the height of said tracks tapers away from said connection region to compensate for a reduction in luminance from said lighting tile array from the electrical connection region which arises from a non-uniform voltage drop which appears along the tracks in use. Advantageously the tracks are fabricated by electroplating: then, as the rate of deposition is determined by the voltage drop along a track during plating, the height of the deposited tracks, and therefore their resistance, will match the profile required in operation to compensate for the reduction in luminance which would otherwise occur.

Description

FIELD OF THE INVENTION[0001]This invention relates to lighting tiles and to organic electronic devices, and to methods for fabricating such tiles and devices.BACKGROUND TO THE INVENTION[0002]As described in our patent application GB2482110, a common approach to boost the conductivity of the anode connection of a large-area organic light-emitting diode (OLED) lighting tile is to use a matrix of electrically conductive tracks. As shown in FIG. 1a, a lighting tile 200 generally has (anode) electrode tracks defining a hexagonal or square grid 102, with an electrical busbar 104 surrounding the grid (the opening shown is to facilitate connection with the counter electrode).[0003]FIG. 1b illustrates that within a given area of the tile, the current primarily flows through the anode electrode in a single dominant direction. For example, if the current is supplied from all edges of the tile, the predominant direction of the current is towards the laterally central position of the lighting ti...

AI Technical Summary

Benefits of technology

This patent describes a method for designing tracks on a lighting tile that can carry current and compensate for voltage drop during use. This is done by matching the resistance of the tracks to their need to carry current. The technique can be applied to various lighting tile technologies, such as OLED and LED devices. The lighting tile can be flexible and the tracks can have increased resistance to reduce cross-talk. The fabrication process involves electroplating the tracks using the same voltage as during operation to ensure uniform luminance. The tracks have a tapered profile that increases the resistance towards the connection region, allowing the current to be transported over a larger area and resulting in a more uniform luminance profile. The increased aperture ratio and improved luminance make the design suitable for large-area devices, such as OLED displays. The second electrically conductive layer can be a continuous layer that acts as a reflective surface to further enhance luminance.

Problems solved by technology

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