Abstract: A method of making an organic electroluminescent (EL) device, includes providing positive photoresist layer a plurality of laterally spaced and electrically insulative pedestal strips in a spatial relationship over anode electrodesdisposed on a substrate; forming an undercut-promoting crosslinking inhibition layer over the pedestal strips, and of a material which produces a diffusable crosslinking inhibition agent; providing and patterning an image reversal photoresist layer on the undercut-promoting inhibition layer into an organic vapor deposition mask oriented over each pedestal strip, and having undercut side surfaces which merge with continuous curvature into a mask top surface and wherein the crosslinking inhibition agent has diffused into the organic vapor deposition mask; forming an organic EL-medium layer between adjacent masks; and forming a plurality of cathode electrodes over the organic EL-medium layer, with the cathode electrodes being laterally spaced by the organic masks.