Fullerene-doped hole transport molecular films for organic light-emitting diodes

摘要

C_(60)-doped N,N′-bis(l-naphthyl)-N, N′-diphenyl-1, 1′-biphenyl-4, 4′-diamine(NPB) film is studied as hole injection layer between indium tin oxide (ITO) and NPB. The doped films on ITO substrates were found to be thermally stable after being annealed at temperatures up to 120 ℃. This was attributed to a strong interaction between NPB and C_(60) providing a dipole force crosslinking NPB molecules, similar to a crosslinked thermoset polymer networks. Furthermore, the C_(60)-doped NPB p-type hole injection layers yield devices having better efficiency and low driving voltage as compared with standard devices with CuPc as the hole injection layers.