Dominik Lungerich

The design of thermally activated delayed fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting, as these new materials offer the possibility of developing low-cost lighting and displays. Here, a comprehensive review of TADF materials is presented, with a focus on linking their optoelectronic behavior with the performance of the organic light-emitting diode (OLED) and related EL devices. TADF emitters are cross-compared within specific color ranges, with a focus on blue, green–yellow, orange–red, and white OLEDs. Organic small-molecule, dendrimer, polymer, and exciplex emitters are all discussed within this review, as is their use as host materials. Correlations are provided between the structure of the TADF materials and their optoelectronic properties. The success of TADF materials has ushered in the next generation of OLEDs.

The emergence of thermally activated delayed fluorescence (TADF) organic compounds has brought about an evolution in the design of OLED emitter design. These materials harvest both singlet and triplet excitons in the device for light emission. This comprehensive review critically examines organic TADF emitters and hosts used in electroluminescent devices.

Hydrogen is a clean fuel with high specific energy and its handling and storage are important toward fuel cell research. Particularly, high-density hydrogen storage is crucial for the viability of future hydrogen-powered devices. This leads to the search for suitable methods; one such option is chemical storage in light materials with large surface areas, such as graphene. Here, the bulk production of graphane by Birch reduction of halogenated (Cl/Br/I) graphene precursors is reported as a potentially scalable procedure. Prior treatment with strong hydrohalic acids is used to remove oxygen-groups and to substitute these with halogens, resulting in effective hydrogenation. An unprecedented level of hydrogen storage is obtained from the iodinated-graphene starting material at 7.44 wt%, far above the U.S. Department of Energy's 2020 system target of 5.5 wt% and close to its ultimate 7.5 wt% goal. As the stored hydrogen is chemisorbed on the graphane scaffold it is stable at both room temperature and on atmospheric exposure, where neither temperature control nor pressure regulation is required. Hydrogen may then be desorbed at elevated temperatures above 400 °C.

Bulk graphane is prepared from halogenated graphene precursors (X = Cl/Br/I), giving levels of stored hydrogen in the material close to the theoretical limit. The graphane produced is stable in air and hydrogen can be subsequently desorbed at elevated temperature. High density hydrogen storage makes graphane a possible option for future hydrogen-powered devices.

Weak Zn⋅⋅⋅N interactions have been exploited in homogeneous palladium catalysis. The selective binding between pyridine-containing compounds and zinc-containing scaffolds (porphyrin or salphen) prevents undesired catalyst inhibition, thus increasing the activity of the palladium-phosphane catalyst. The picture illustrates how a magician uses the “Zn⋅⋅⋅N weak interactions” trick to increase the performance of the palladium catalyst inside an Erlenmeyer flask under the watchful eye of a bunny. More information can be found in the Full Paper by R. Gramage-Doria et al. (DOI: 10.1002/chem.201604780).