A light emitting device, comprising a flexible substrate (2) with a single, structured conductive layer (5), and a plurality of LEDs (3) arranged on said substrate (2), said structured conductive layer (5) forming electrodes for driving said LEDs (3). The structured conductive layer comprises a plurality of heat dissipating pads (8), each having an area significantly larger than the area of each LED (3), and each LED (3a) is thermally connected to at least one of said pads (8a), and electrically connected in series between two pads (8a, 8b). Through this design, each LED is thermally connected to a relatively large heat dissipating area, and the thermal energy built up in the LED will be distributed over this area, and then dissipated upwards and downwards from this area. As the addressing can be handled by a single conducting layer, the flexibility of the substrate is improved compared to multilayer substrates. By connecting each LED in series between two pads, a very large portion of the conducting layer can be used for the pads, and very little area needs to be occupied by conducting tracks, which otherwise may be a problem with single layer designs.