Recent Advances in White Organic Light‐Emitting Materials and Devices (WOLEDs)

Abstract

WOLEDs offer new design opportunities in practical solid-state lighting and could play a significant role in reducing global energy consumption. Obtaining white light from organic LEDs is a considerable challenge. Alongside the development of new materials with improved color stability and balanced charge transport properties, major issues involve the fabrication of large-area devices and the development of low-cost manufacturing technology. This Review will describe the types of materials (small molecules and polymers) that have been used to fabricate WOLEDs. A range of device architectures are presented and appraised.

Cyclometalated Ir(III) Complexes for High-Efficiency Solution-Processable Blue PhOLEDs

“…1/τ q =k r +k nr +k q (2) where, k q is the concentration quenching rate, which was evaluated by subtracting the decay rate of 0.01% complex:zeonex (eq. 1) from the decay rate of 12% complex:zeonex (eq.…”

“…2,3 Phosphorescent cyclometalated complexes provide improved electroluminescence efficiencies by utilizing both triplet and singlet electroexcitation pathways. They have the benefits of relatively short excited state lifetimes, high photoluminescence efficiency, good color tuneability and general thermal and electrochemical stability.…”

Homoleptic Iridium(III) Compounds Bearing Bulky Bipyridine Ligand for Potential Application to Organic Light‐emitting Diodes

“…Interestingly, stronger absorptions of 1 and 2 were observed in the region of 1 MLCT than that of the reference FIrpic, which implies the presence of significant singlettriplet coupling due to strong spin-orbit coupling in both compounds. The emission patterns of the two compounds are very similar to each other, but the emission maximum of 2 is blue-shifted by 2-3 nm relative to that of 1.…”

“…The residue was purified by column chromatography (CH 2 Cl 2 , R f = 0.85) to give 46% yield of solid product. 1 13 Synthesis of Fac-Tris(2 0 ,6 0 -Diisopropoxy-4-tert-Butyl-2,3 0 -Bipyridinato-N,C 4 )Ir(III) (2): The product was prepared using the same procedure of 1 except that 2 0 ,6 0 -diisopropoxy-4-tert-butyl-2,3 0 -bipyridine was used instead of 2 0 ,6 0 -diisopropoxy-2,3 0 -bipyridine. Yield: 42% (CH 2 Cl 2 , …”

“…1 To achieve WOLEDs with high efficiency and low power consumption, the employment of phosphorescent emitters is essential, because triplet emitters have internal quantum efficiencies of nearly 100%. 2 Three colors should be balanced to produce white light, which requires red, green, and blue emitters in the emitting layers.…”