The improved performance in inverted organic light-emitting diodes using the hybrid- p-doped hole transport layer.

The inverted organic light-emitting diodes (IOLEDs) have been fabricated using the hybrid- p-doped hole transport layer consisting of MoO-doped N, N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB:MoO) and 2,3,5,6-Tetrafluoro-7,7,8,8,-tetracyano-quinodimethane-doped NPB (NPB:F-TCNQ). Compared with the IOLED using the 20 nm NPB:MoO/Al, the one using the 10 nm NPB:F-TCNQ/10 nm NPB:MoO/Al showed increased performance, attributed to the higher conductivity of NPB:F-TCNQ than NPB:MoO, reducing the ohmic loss in hole conduction through the combined 10 nm NPB:F4-TCNQ and 10 nm NPB:MoO than through the 20 nm NPB:MoO; it also presented improved performance than the IOLED using the 20 nm NPB:F-TCNQ/Al, ascribed to the non-ohmic contact formation between NPB:F-TCNQ and Al, resulting from that the p-doping effect of F-TCNQ in NPB was significantly suppressed by the Al deposition in the interfacial zone. The hybrid p-doping of hole transport layer can offer a large space to promote the performance of IOLEDs. [ABSTRACT FROM AUTHOR]