Single-Layer Blue Electrophosphorescent Organic Light-Emitting Diodes Based on Small-Molecule Mixed Hosts: Comparison between the Solution and Vacuum Fabrication Processes

Abstract

Single-layer and efficient blue phosphorescence organic light-emitting diodes (PHOLEDs) utilizing a small molecule host, bis[3,5-di(9H-carbazol-9-yl)phenyl]diphenylsilane (SimCP2), as the host material were investigated. All active components including SimCP2, 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7), and iridium(III) bis[(4,6-di-fluorophenyl)-pyridinato-N,C2] picolinate (FIrpic) were mixed in an organic solution for wet processing in the fabrication of single-layer PHOLEDs. The device's performance significantly exceeds other small-molecule-host, single-layer, blue PHOLEDs fabricated by the solution process. With minimum efficiency roll-off, a maximum current efficiency of 13.6 cd/A, power efficiency of 8 lm/W, external quantum efficiency of 4.71%, and Commission Internationale de L'Eclairage (CIEx,y) coordinates of (0.15,0.36) at 600 cd/m2 have been achieved. In addition, the device performance of the solution-processed single-layer PHOLED is much greater than that of its vacuum-deposited counterparts.