An organic light emitting device includes a transistor having gate, source, and drain electrodes, and first electrode connected to one of the source or drain electrodes. The device also includes an emitting layer positioned on the first electrode and a second electrode positioned on the emitting layer. Each of the source and drain electrodes includes first, second, and third layers having different tapered angles. The first electrode may include a metallic layer and a conductive layer, with a tapered angle of the metallic layer being different from a tapered angle of the conductive layer.