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Recently deuteration has become a key technology for enhancing lifetime of OLED materials without affecting other performance parameters like efficiency and voltage. Over the past years, we intensively investigated the impact of the deuteration degree and pattern on the device performance. The focus of our investigation was triplet matrix materials (TMMs) in the emissive layer and the electron‐blocking layer (EBL). In this paper, we will discuss various aspects of the deuteration of OLED materials: from driving further performance improvements to scale‐up processes. [ABSTRACT FROM AUTHOR]

In order to fulfill the demand for ever‐improving OLED panel properties, material design has to adapt quickly. We propose multiscale material simulations as a tool to elucidate structure‐property relations guiding us towards materials with desired properties. As an example, we present benchmarking and application of a simulation workflow for triplet emitter optical orientation validated by experiment. Using this we were able to improve the isotropic optical orientation of the phosphorescent triplet emitter Ir(ppy)3 to unprecedented orientation parameters o<0.1. This means that >90% of the emitter transition dipoles can be in the substrate plane, allowing for better outcoupling and thus higher external quantum efficiency. Such a high degree of orientation realized by help of material simulation is a remarkable result for octahedral (non‐planar) complexes based on Ir(ppy)3. [ABSTRACT FROM AUTHOR]

A series of novel platinum-containing carbazole monomers and polymers was synthesized and fully characterized by UV-VIS absorption, luminescence, and photoinduced absorption studies. In these compounds, a carbazole unit is incorporated into the main chain via either a para- or a meta-linkage. We discuss the effects of linkage and polymerization on the energy levels of S1, T1, and Tn. The S1-T1 splitting observed for the meta-linked monomer (0.4 eV) is only half of that in the para-linked monomer (0.8 eV). Upon polymerization, the exchange energy in the para-linked compound reduces, yet still remains larger than in the meta-linked polymer. We attribute the difference in exchange energy to the difference in wave function overlap between electron and hole in these compounds. [ABSTRACT FROM AUTHOR]

The synthesis of a new tetrakis(trisalkoxy-phenylethynyl)pyrene discotic mesogen that forms hexagonal and rectangular columnar mesophases is reported. In addition to a high fluorescence quantum yield in solution, the molecule exhibits a quantum yield in the crystalline phase as high as 62 (plusmn) 6% and this value is one of the highest fluorescence quantum yields reported so far for discotics.

A new matrix system for phosphorescent organic light-emitting diodes (OLEDs) based on an electron transporting component attached to an inert polymer backbone, an electronically neutral co-host, and a phosphorescent dye that serves as both emitter and hole conductor are presented. The inert co-host is used either as small molecules or covalently connected to the same chain as the electron-transporting host. The use of a small molecular inert co-host in the active layer is shown to be highly advantageous in comparison to a purely polymeric matrix bearing the same functionalities. Analysis of the dye phosphorescence decay in pure polymer, small molecular co-host film, and their blend lets to conclude that dye molecules distribute mostly in the small molecular co-host phase, where the co-host prevents agglomeration and self-quenching of the phosphorescence as well as energy transfer to the electron transporting units. In addition, the co-host accumulates at the anode interface where it acts as electron blocking layer and improves hole injection. This favorable phase separation between polymeric and small molecular components results in devices with efficiencies of about 47 cd/A at a luminance of 1000 cd/m2. Investigation of OLED degradation demonstrates the presence of two time regimes: one fast component that leads to a strong decrease at short times followed by a slower decrease at longer times. Unlike the long time degradation, the efficiency loss that occurs at short times is reversible and can be recovered by annealing of the device at 180 °C. We also show that the long-time degradation must be related to a change of the optical and electrical bulk properties. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

Although carbazole-containing copolymers are frequently used as hole-transporting host materials for polymer organic light-emitting diodes (OLEDs), they often suffer from the formation of undesired exciplexes when the OLED is operated. The reason why exciplexes sometimes form for electrical excitation, yet not for optical excitation is not well understood. Here, we use luminescence measurements and quantum chemical calculations to investigate the mechanism of such exciplex formation for electrical excitation (electroplex formation) in a carbazole-pyridine copolymer. Our results suggest that the exciplex is formed via a positively charged interchain precursor complex. This complex is stabilized by interactions that involve the nitrogen lone pairs on both chain segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]