Reported here are C1‐linked spiro‐bifluorene dimers. A comprehensive study is carried out to analyze the electronic properties of these highly twisted structures. This work shows that the C1‐position enables the design of pure hydrocarbon materials, with a high triplet energy, for hosting blue phosphors in efficient phosphorescent OLEDs (PhOLEDs). To date, this work describes the highest performance of blue PhOLEDs ever reported for pure hydrocarbons (external quantum efficiency of ca. 23 %), thus highlighting the potential of the C1‐spirobifluorene scaffold in organic electronics.

Reported here are C1-linked spiro-bifluorene dimers.Acomprehensive study is carried out to analyze the electronic properties of these highly twisted structures.T his work shows that the C1-position enables the design of pure hydrocarbon materials,w ith ah igh triplet energy,f or hosting blue phosphors in efficient phosphorescent OLEDs (PhOLEDs). To date,t his work describes the highest performance of blue PhOLEDs ever reported for pure hydrocarbons (external quantum efficiency of ca. 23 %), thus highlighting the potential of the C1-spirobifluorene scaffold in organic electronics.Since their discovery, [1] phosphorescent organic light-emitting diodes (PhOLEDs), which use heavy-metal complexes emitters dispersed in ah ost material, have attracted great attention. [1][2][3][4] In such devices it is crucial to prevent energy back transfers from the emitter to the host and to favor the confinement of excitons.T his setup can be achieved by combining in the host ahigh triplet energy (E T )and abalanced hole/electron transport. Theclassic molecular design strategy consists of linking,within the host, an electron-rich fragment with an electron-poor fragment and inducing a p-conjugation disruption between them. This strategy allows adjustment of the molecular frontier orbitals energy levels without extending the conjugation length, thus keeping ah igh E T .V arious electron-rich (carbazole, [5,6] quinolinophenothiazine, [7] dihydroacridine [8] etc.) and electron-poor (phosphine oxide, [6] pyridine, [9,10]

A novel filtering dielectric resonator (DR) antenna (DRA) is designed in this article. By using a single-layer planar feed structure, the TM 01δ and TM 011+δ modes of a cylindrical DR are excited. The proposed filtering DRA achieves a good omnidirectional radiation performance and a flat gain response. By loading a crossed patch with four shorting pins on the feed structure, the lower edge of the passband obtains a steep roll-off rate. By plating four metal patches on the side wall of the DR, a radiation null (RN) is successfully introduced at the upper sideband of the DRA. The suppression levels of the proposed filtering DRA in the lower and upper stopbands are above 18 dB. Therefore, the proposed filtering DRA achieves filtering function without additional circuits. For demonstration, a prototype DRA is fabricated and measured. The simulated and measured results are basically consistent.