Simplified Bilayer White Phosphorescent Organic Light-Emitting Diodes

Abstract

We report on highly efficient blue, orange, and white phosphorescent organic light‐emitting diodes consisting only two organic layers. Hole transporting 4, 4,’ 4”‐tris (N‐carbazolyl)triphenylamine (TcTa) and electron transporting 2‐(diphenylphosphoryl) spirofluorene (SPPO1) are used as an emitting host for orange light‐emitting bis(3‐benzothiazol‐2‐yl‐9‐ethyl‐9H‐carbazolato) (acetoacetonate) iridium ((btc)2(acac)Ir) and blue light‐emitting iridium(III)bis(4,6‐difluorophenyl‐pyridinato‐N,C2’) picolinate (FIrpic) dopant, respectively. Combining these two orange and blue light‐emitting layers, we successfully demonstrate highly efficient white PHOLEDs while maintaining Commission internationale de l'éclairage coordinates of (x=0.373, y=0.443). Accordingly, we achieve a maximum external quantum, current, and power efficiencies of 12.9%, 30.3 cd/A, and 30.0 lm/W without out‐coupling enhancement.

Highly Conductive PEDOT:PSS Films with 1,3‐Dimethyl‐2‐Imidazolidinone as Transparent Electrodes for Organic Light‐Emitting Diodes

“…The device areas were 2 × 2 mm 2 . The current–voltage–luminance characteristics and electroluminescence spectra were measured with a source‐measure unit system (Keithley 238) and a goniometer‐equipped spectroradiometer (Minolta CS‐2000) …”

Enhanced outcoupling in down-conversion white organic light-emitting diodes using imprinted microlens array films with breath figure patterns

“…To realize white OLEDs, a most common approach is to stack red, green, and blue emissive layers in the device [1,29]. However, the stacked white OLEDs suffer from fabrication complexity, difficulty in solution process, and color-dependent lifetime [1,29,30]. Using downconversion materials with blue-emitting OLEDs is an alternative approach [31][32][33], which is widely used in inorganic white light-emitting diodes based on yttrium aluminum garnet phosphors and GaN diodes.…”

Luminescence enhancement of OLED lighting panels using a microlens array film

“…In general, OLED lighting can offer high luminous efficiency, color tunability, flexibility, transparency, low thickness, large luminescence area, etc. [1][2][3]. In OLED lighting applications, a large illumination area is favored.…”