It has been found that insertion of a thin Bit buffer layer between the At electrode and the MEH-PPV layer results in a significantly higher current density in ITO/MEH-PPV/Al polymer light-emitting diodes due to it reduction of the potential barrier at the cathode-polymer interface. The photoluminescence is found to increase with the addition of porphyrin-containing platinum as the central atom, showing that some of the triplet excitons decay radiatively as a result of mixing porphyrin. (c) 2005 Elsevier B.V. All rights reserved.