Efficient electroluminescence was revealed in single-layer light-emitting d
iodes based on electron-hole conducting polymers containing the nanocrystal
line phase of cyanine dyes (J-aggregates). These species exhibit a very nar
row emission band with a maximum in the red to infrared spectrum range. The
J-aggregates play an active role in the charge carrier transport of the co
mposites. (C) 1999 American Institute of Physics. [S0003-6951(99)04738-5].