Active matrix electroluminescent display devices, and their manufacture

Physical barriers ( 210 ) are present between neighbouring pixels ( 200 ) on a circuit substrate ( 100 ) of an active-matrix electroluminescent display device, particularly with LEDs ( 25 ) of organic semi conductor materials. The invention forms these barriers ( 210 ) with metal or other electrically-conductive material ( 240 ), that is insulated ( 40 ) from the LEDs but connected to the circuitry within the substrate ( 100 ). This conductive barrier material ( 240 ) backs-up or replaces at least a part of the drive supply line ( 140,240 ) to which the LEDs are connected by a drive element T 1 . This transfers the problem of line resistance and associated voltage drop from within the circuit substrate ( 100 ), where it is severely constrained, to the much freer environment of the pixel barriers ( 210 ) on the substrate ( 100 ) where the conductive barrier material ( 240 ) can provide much lower resistance. Very large displays can be made with low voltage drops along this composite drive supply line ( 140,240 ). Furthermore, the structure can be optimised to form a smoothing capacitor (Cs) between this drive supply line ( 140,240 ) with its conductive barrier material ( 240 ) and the further supply line ( 230 ) of the LED upper electrodes ( 23 ) extending on an insulating coating ( 40 ) over the top of the conductive barrier material ( 240 ).