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Organic electroluminescent (EL) devices based either on small molecules or on polymers are of great current interest due to their potential application in full color display panels covering a variety of emission colors from blue to red [1–4]. For polymer electroluminescent devices, to control and improve light emission, the commonly used concept is to blend a fluorescent dye into a proper polymer. Transfer of excitation from host to the guest is promoted by three processes: Forster transfer of singlet excitons generated on the host to the guest, Dexter transfer of both singlet and triplet excitons generated on the host to the dopant, and the direct generation of singlet and triplet excitons on the guest [5]. Forster transfer of energy from an absorbing host to an emitting guest has been used to realize different color emission. Also, it reduces self-absorbance by shifting the emission away from the absorption edge in blends. In general, a significant spectra overlap (overlap of the host emission spectrum and the dopant absorption spectrum) is a key requirement for efficient energy transfer. The transfer rate parameters are proportional to overlap area [6, 7]. In this letter we investigate energy transfer from the semiconducting polymer, poly(N-vinyl-carbazole) (PVK) to organic molecule tetra-methylester of perylene3,4,9,10-tetracarboxylicacid (TMEP). We examine both the PL and EL spectra for a single layer made from PVK doped with TMEP. Scheme 1a shows the chemical structure of TMEP. TMEP is liquid crystalline material in which the prox |
