Highly Efficient Hybrid White Tandem Organic Light‐Emitting Diodes with MoO₃ Layer

Abstract

Electroluminescence (EL) characteristics have been studied for a hybrid tandem white organic light emitting diode (OLED) with a blue emitting fluorescent EL1 unit based on BCzVBi and a yellow emitting phosphorescent EL2 unit based on (fbi) 2 Ir(acac), where a MoO 3 layer is inserted between EL1 and EL2 units as charge generation layer (CGL). Maximum current and power efficiencies of 68.1 cd/A and 29.2 lm/W were obtained, respectively, while the current and power efficiencies at luminance of 1000 cd/m 2 were 68.0 cd/A and 24.6 lm/W. The yellow emission appears from about 4.5 V firstly, while the blue emission starts to appear from about 5.4 V. It was found that charge generation from CGL of MoO 3 /NPB bilayer occurred at high voltages of above 5.4 V but not at low voltages below 5.2 V.

A Bipolar and Small Singlet‐Triplet Splitting Energy Host with Triplet Energy Lower Than a Blue Phosphor for Phosphorescent OLEDs in Panchromatic Range

“…It can be explained by the higher energy band-gap (E g ) of TCPZ than CBP. 16 efficiencies at lower (3% and 6%) and higher (12%) doping concentrations are mainly due to the insufficient luminescent centers and high concentration quenching, [30] as well as triplet-triplet exciton annihilation in FIrpic at high doping concentration. For instance, device R showed maximum efficiency of 9.3 cd•A 1 (13.2%), while those in our previous work are 8.3%.…”

“…Thus, suitable host materials are generally indispensable to high performance PhOLEDs. [16] In this sense, using one host to achieve high performance blue, green and red electroluminescence (EL) through a simple material system is an interesting and important issue, which can reduce the production cost of materials and simplify the manufacture process. However, RGB PhOLEDs obtained by incorporating corresponding primary-color emitter often require different hosts to achieve highly efficient energy transfer from host to the emitter.…”

Highly Efficient White Organic Light-Emitting Diodes Based on Phosphorescent Iridium Complexes with Multi-Light-Emitting Layers

“…To accomplish high performance WOLEDs, three primary (e.g., red, green, blue) or two adscititious (e.g., blue, orange or yellow) dyes are indispensable. At present, fluorescent and phosphorescent hybrid WOLEDs that integrate stable blue fluorescent and red/green/orange phosphorescent emitters have realized certain success in relatively high efficiency and excellent stability [8][9][10][11][12][13]. Whereas, to obtain high electroluminescent (EL) efficiency, it is necessary to design reasonable device structure and select matched blue fluorescent materials with high photo-luminescent quantum yields (PLQYs).…”

A Bulky Pyridinyl?uorene/Triphenylamine Hybrid Used as Host Material for Heavily‐Doped Blue Electrophosphorescent Devices

“…[1][2][3][4][5][6] Among the large number of devices, phosphorescent organic light-emitting diodes (PhOLEDs) are outstanding since the potential of 100% internal quantum efficiency resulted from strong spin-orbit coupling caused by heavy atoms, which could lead to an efficient intersystem crossing and harvest both triplet and singlet excitons. [5][6][7][8][9][10] However, phosphor emitters often suffer self-quenching and triplet-triplet annihilation at high doping concentration. [2,[11][12][13] PhOLEDs often employ host-guest system to resolve this problem.…”