A white-light electroluminescent device having an adjustable color temperature substantially on a predetermined range of a Planckian locus within the 1976 Commission Internationale de l'Eclairage (CIE) uniform chromaticity scale diagram. According to one embodiment, a first light-emitting element having a fixed ratio of at least two different species of emitters combined to produce a set of chromaticity coordinates at a predetermined white point substantially on the Planckian locus. A second light-emitting element having at least a single species of emitters produces a set of chromaticity coordinates. The set of chromaticity coordinates are positioned along a projected line extending from the Planckian locus and through the chromaticity coordinates of the first light-emitting layer. A controller adjusts the voltage or current associated with the first and second light-emitting elements to provide white light with a predetermined range of chromaticity coordinates substantially on the Planckian locus.