Poly (p-phenyleneneacetylene) light-emitting diodes

A light-emitting diode comprising:

• (a) an electroluminescent acetylene-based polymer layer, having first and second surfaces;
• (b) a base electrode layer adjacent to the first surface of the electroluminescent acetylene-based polymer layer;
• (c) a second electrode adjacent to the second surface of the electroluminescent acetylene-based polymer layer;
• (d) means for providing an electrical connection between the base electrode layer and the second electrode;
• and
• (e) means for providing current;
• wherein
• (i) the electroluminescent acetylene-based polymer layer comprises a poly(.rho.-phenyleneacetylene) polymer of the formula --[--C.tbd.C--Ar--C.tbd.C--Ar--].sub.n --, having a number average molecular weight of about 2,000-100,000, wherein Ar is a (C.sub.6 -C.sub.24)arylene group and n=12-200;
• (ii) the second electrode comprises a layer of a material coated on a substrate, wherein the material is capable of injecting holes into the electroluminescent polymer;
• and
• (iii) the layer of hole-injecting material is a layer of an oxide of a metal selected from the group consisting of a Group IlIA metal, a Group IVA metal, and mixtures thereof.

A light-emitting diode comprising:

• (a) an electroluminescent acetylene-based polymer layer, having first and second surfaces;
• (b) a layer of a metal adjacent to the first surface of the electroluminescent acetylene-based polymer layer;
• (c) a layer of indium-tin oxide having first and second surfaces, wherein the first surface is adjacent to the second surface of the electroluminescent acetylene-based polymer layer, and wherein the mixed-metal oxide has a work function at least about 0.5 eV greater than the work function of the metal;
• (d) a glass substrate adjacent to the second surface of the indium-tin-oxide layer;
• and
• (e) means for providing an electrical connection between the aluminum layer and the indium-tin-oxide layer;
• wherein the electroluminescent acetylene-based polymer layer comprises a poly(.rho.-phenyleneacetylene) polymer of the formula --[--C.tbd.C--Ar--C.tbd.C--Ar--].sub.n --, having a number average molecular weight of at least about 2,000-100,000 wherein Ar is an arylene group and n=12-200.