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Durham University

Department of Physics

Staff profile

Publication details for Associate Professor Fernando Dias

S.M. King, M. Cass, M. Pintani, C. Coward, F.B. Dias, A.P. Monkman & M. Roberts (2011). The contribution of triplet-triplet annihilation to the lifetime and efficiency of fluorescent polymer organic light emitting diodes. Journal of Applied Physics 109(7): 074502

Author(s) from Durham

Abstract

We demonstrate that the fast initial decay of a prototypical fluorescent polymer based organic light emitting diode device is related to the contribution that triplet-triplet annihilation makes to the device efficiency. We show that, during typical operating conditions, approximately 20% of the device efficiency originates from the production of singlet excitons by triplet-triplet annihilation. During prolonged device operation, the triplet excitons are quenched much more easily than the emissive singlets; thus, the contribution to the efficiency from triplet-triplet annihilation is lost during the early stages of the device lifetest. The fast initial decay of the device luminance can be removed by incorporating a triplet quenching additive into the active layer to remove any effect of triplet-triplet annihilation; this yields an increase in the device lifetime of greater than 3x and an even more significant improvement in the initial luminance decay. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3561430]