Near-infrared electroluminescence from conjugated polymer/lanthanide porphyrin blends

Near-infrared-emitting polymer light-emitting diodes (PLEDs) have been fabr icated using blends of conjugated polymers and lanthanide tetraphenylporphy rin complexes. Host polymers include MEH-PPV and a bis-alkoxy-substituted p oly(p-phenylene) (PPP-OR11), and the lanthanide complexes include Yb(TPP)ac ac and Er(TPP)acac (where TPP=5,10,15,20-tetraphenylporphyrin and acac=acet ylacetonate). Electroluminescence (EL) is observed at 977 nm from devices f abricated using MEH-PPV or PPP-OR11 blended with Yb(TPP)acac, and EL is obs erved at 1560 nm from a device fabricated using a blend of MEH-PPV and Er(T PP)acac. Visible EL from the host polymers is strongly suppressed in all of the devices, however, in the device fabricated using the PPP-OR11 polymer blue emission from the host is completely quenched. Very efficient quenchin g of the EL from the host in the PPP-OR11 device is believed to occur due t o efficient Forster energy transfer, which is facilitated by the excellent spectral overlap between the PPP-OR11 fluorescence and the Soret absorption band of the TPP ligand. (C) 2001 American Institute of Physics.