Designs and arrangements for sublimation cells are provided, which enriches an inert carrier gas with organic vapor such that the partial pressure of the organic vapor is highly stable in time. Stability is achieved by controlling the local rates of evaporation along the solid-gas interface through one or more crucibles, thereby reducing the effects of greater headspace and lowering interfacial area as the source depletes. Local evaporation rates also can be controlled using either temperature distribution or convective flow fields.