White polymer light-emitting diodes based on dibenzo-24-crown-8 decorated orange-emitting iridium complexes

Abstract

Two orange phosphorescent iridium complexes decorated by dibenzo-24-crown-8 unit as the dopants were used into polymer light-emitting diodes (PLEDs) with a configuration of ITO/PEDOT:PSS/emission layer (EML)/CsF/Al. Monochromic orange-emitting PLEDs using complex 2 as dopant and poly(N-vinylcarbazole) (PVK) as host exhibit best device performance with a peak luminous efficiency (LE) of 8.94 cd/A at a current density of 1.3 mA/cm2 and a Commission Internationale de L'Eclairage (CIE) coordinate of (0.52, 0.41). More importantly, several white polymer light-emitting diodes (WPLEDs) were also fabricated with the skyblue–orange dual emitters system. The WPLEDs combination of the orange phosphor complex 2 with skyblue phosphor iridium(III)bis(2-(4,6-difluorophenyl)-pyridinato-N,C2′)picolinate (FIrpic) in a single-emissive-layer exhibit best electroluminescent performances with a maximal LE of 5.12 cd/A at a current density of 2.63 mA/cm2, a turn on voltage of 6.5 V and a CIE coordinates of (0.33, 0.39), which is very close to the ideal CIE coordinate of (0.33, 0.33) for pure white color.