LIGHT-EMITTING-DIODES FABRICATED WITH CONJUGATED POLYMERS - RECENT PROGRESS

We consider the present understanding of the operation of light-emitti ng diodes which use conjugated polymers for both charge transport and emission. We highlight the improvement to the electroluminescence effi ciency that can be produced by the use of two polymer layers selected so that the heterojunction between the two layers is able to confine c harge and thus bring about efficient electron-hole capture to generate excitons. We also report recent results on the fabrication of diodes on top of non-transparent substrates such as silicon. This requires th e deposition of a transparent top electrode, and we have used indium-t in oxide in this role.