A method is to form a thin film light emitting device. The method includes providing a transparent substrate. A transparent anode layer, a light emitting layer, a metal cathode layer are sequentially formed on the transparent substrate. A sealant layer is formed to at least cover the light emitting layer and the metal cathode layer. A covering layer having a covering surface is provided. An evaporation process is performed to form an active absorption layer on the covering surface of the covering layer. The covering surface of the covering layer covers on a portion of the sealant layer above the metal cathode layer. The covering layer can have a recess region that is to be formed the active absorption layer thereon. Alternatively, the active absorption layer can be evaporated before the sealant is formed. Moreover, the active absorption layer can be replaced with an insulating layer.
