We present the organic electroluminescent devices and lasers of which the colors are tuned by utilizing the Forster excitation energy transfer. Fluorene-based light emitting polymers, poly(2,7-bis(p-stiryl)-9,9'-di-n-hexylfluorene sebacate) (PBSDHFS), poly(9,9'-di-n-hexyl fluorenediylvinylene-alt-1,4-phenylenevinylene) (PDHFPPV), and a laser dye, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) were used as the components of the energy transfer systems. Color-tunable photoluminescence, electroluminescence, and laser emission in the PBSDHFS/PDHFPPV binary and PBSDHFS/PDHFPPV/DCM ternary blends are demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.