Light-emitting diodes based on dipyrido[3,2-a:2',3'-c]phenazine (dppz) and Re(CO)(3)Cl-dipyrido[3,2-a:2',3'-c]phenazine (Re(CO)(3)Cl(dppz)) dyes incorporated into a poly(N-vinylcarbazole) (PVK) host have been fabricated. The dppz dyes doped into PVK show PL spectra that have large Stokes shifts (more than 9000 cm(-1)), but the dppz emission does not appear in the EL spectra. The Re-based dyes show virtually no emission in the PL spectra when doped into PVK, however, the emission from the Re-based dyes dominates the EL spectra. This is because the Re-based dyes are able to transport efficiently hole and electron carriers leading to electronic excitation of the dye excited state through charge-carrier mechanisms. (C) 2003 Elsevier B.V. All rights reserved.