Advanced Device Architecture for Highly Efficient Organic Light‐Emitting Diodes with an Orange‐Emitting Crosslinkable Iridium(III) Complex

Abstract

Transition-metal complexes in organic light-emitting diodes (OLEDs) can overcome the efficiency limit of fluorescent devices. Due to the strong spin-orbit coupling of these complexes, both singlet and triplet excitons can be harvested and an internal quantum efficiency of 100 % is possible.[1-3] Many complexes with transition-metals, such as iridium, ruthenium, osmium and platinum have been synthesized to develop highly efficient phosphorescent OLEDs (PHOLEDs), [4][5][6][7][8] because a simple ligand-variation allows for a wide range of emission-colors and for tuning of the chemical properties.

Recent Developments in the Application of Phosphorescent Iridium(III) Complex Systems

“…[136,137] Testing several materials in a multilayer device assembly, a maximum efficiency of 4.9% (at 100 cd m 2 ) could be realized. [137] Ulbricht and co-workers [138] and Rehmann et al [139] reported the synthesis of oxetane-functionalized bis-cyclometallated iridium(III) acetoacetate complexes and the optimization of multilayer OLEDs employing these emitters, which were covalently incorporated into a crosslinked matrix. The hole-transport layers (HTL) as well as the matrix of the EML consisted of oxetane-equipped tetraphenylbenzidine (TPD) derivatives, which were crosslinked by photo-induced cationic-ring-opening polymerization after deposition from solution.…”

“…While vapor-deposited devices often exhibit superior characteristics, solution-processed devices are catching up to show comparable performance. [138,[192][193][194][195][196][197] Besides the optimization of the employed layers, further technical approaches are pursued to improve the device outcoupling. [196,197] The application of transparent organic [198] or semitransparent metal cathodes [199] leads to so-called top-emissive devices with high power and EQE, which enables the fabrication of fully transparent displays and lighting devices.…”

The Simple Way to Solution‐Processed Multilayer OLEDs – Layered Block‐Copolymer Networks by Living Cationic Polymerization

“…To keep the technical aspects as consistent as possible with our earlier publications, and to show clearly the impressive improvements, we intentionally chose to use an established material set. The transfer to more recent materials in the field of polymer LEDs (e.g., better backbone polymers, triplet emitters [37] ) is straightforward, but it would be difficult to clearly differentiate and assign the improvements to the new concept alone. Please note that it is absolutely effectual to demonstrate the new concepts.…”

Lumineszenz eines Platin(II)‐Komplexes in gelierenden Nanofasern und elektrolumineszierenden Filmen

“…Eine Optimierung des Ladungstransports in der Matrix wurde durch Versetzen mit OXD-7 erzielt (siehe Hintergrundinformationen). [14] Zusätzlich wurden in der optimierten OLED QUPD [15] und OTPD [15] …”