The present invention provides a planar electroluminescence (EL) device comprising a substrate layer, an electrode layer, a light emitting layer, and a modulating layer, wherein the electrode layer comprises a plurality of electrodes arranged on a same level over the substrate layer, and there is no contact between adjacent electrodes. In one embodiment, the device further comprises a hole injection layer (HIL), a hole transport layer (HTL), an electron injection layer (EIL) and an electrode transport layer (ETL). In one embodiment, the light emitting layer comprises organic light emitting polymers or organic light emitting molecules. The device of the present invention would emit light when liquid, polar component, or conductive solution is written directly on the light emitting layer. In one embodiment, the device can emit light for prolonged period when the light emitting layer is coated or deposited with conductive material.