A source to facilitate precise vapor deposition in processes to obtain organic light emitting diodes (OLEDs) in a display panel, includes forming a plurality of grooves on a first substrate; in filling organic light emitting materials into the grooves and providing a second substrate to receive the vaporized organic light emitting materials. The first substrate is aligned with the second substrate and the first substrate is heated to vaporize the organic light emitting materials in the grooves. The vapor deposition regions of the second substrate form an organic light emitting material layer after the deposition, the layer can then be used in an OLED display panel. The shadow effect is greatly reduced, a method for the procedure is also disclosed.