A method for making an organic light emitting diode includes providing a preform structure including an anode electrode, a hole transport layer, and an organic light emitting layer stacked on each other in that order. The organic light emitting layer has a first surface and a second surface opposite to the first surface, and the second surface is in direct contact with the hole transport layer. A carbon nanotube structure is located on the first surface. A monomer solution is disposed on the carbon nanotube structure, and the monomer solution is formed by dispersing a monomer into an organic solvent. The monomer is polymerized to form a polymer, and a cathode electrode is formed on the polymer.