Highly efficient thermally activated delayed fluorescence (TADF) molecules are in urgent demand for solid‐state lighting and full‐color displays. Here, the design and synthesis of three triarylamine‐pyridine‐carbonitrile‐based TADF compounds, TPAPPC, TPAmPPC, and tTPAmPPC, are shown. They exhibit excellent photoluminescence quantum yields of 79−100% with small ΔEST values, fast reverse intersystem crossing (RISC), and high horizontal dipole ratios (Θ// = 86−88%) in the thin films leading to the enhancement of device light outcoupling. Consequently, a green organic light‐emitting diode (OLED) based on TPAmPPC shows a high average external quantum efficiency of 38.8 ± 0.6%, a current efficiency of 130.1 ± 2.1 cd A–1, and a power efficiency of 136.3 ± 2.2 lm W–1. The highest device efficiency of 39.8% appears to be record‐breaking among TADF‐based OLEDs to date. In addition, the TPAmPPC‐based device shows superior operation lifetime and high‐temperature resistance. It is worth noting that the TPA‐PPC‐based materials have excellent optical properties and the potential for making them strong candidates for TADF practical application.
For the application of organic light-emitting diodes (OLEDs) in lighting and panels, the basic requirement is to include a full spectrum color range. Compared with the development of blue and green luminophores in thermally activated delayed fluorescence (TADF) technology, the progress of orange-to-red materials is slow and needs further investigation. In this study, three diboron compound-based materials, dPhADBA, dmAcDBA, and SpAcDBA, were designed and synthesized by nucleophilic arylation of three amine donors on 9,10-diboraanthracene (DBA) in a two-step reaction. With increasing electron-donating ability, they show orange-to-red emission with TADF characteristics. The electroluminescence of these diboron compounds exhibits emissions λ max at 613, 583, and 567 nm for dPhADBA, dmAcDBA, and SpAcDBA, respectively. It is noteworthy that the rod-like D-A-D structures can achieve high horizontal ratios (84−86%) and outstanding device performance for orange-to-red TADF OLEDs: the highest external quantum efficiencies for dPhADBA, dmAcDBA, and SpAcDBA are 11.1 ± 0.5, 24.9 ± 0.5, and 30.0 ± 0.8%, respectively. Therefore, these diboron-based molecules offer a promising avenue for the design of orange-to-red TADF emitters and the development of highly efficient orange-to-red OLEDs.
Owing to the high technology maturity of thermally activated delayed fluorescence (TADF) emitter design with a specific molecular shape, extremely high-performance organic light‐emitting diodes (OLEDs) have recently been achieved via...
In contrast to the normal formation of cubic metal halide perovskite nanocrystals, CsPbCl 3 cubes and edge-truncated cuboids have been synthesized by simply mixing CsCl, PbCl 2 , and sodium dodecyl sulfate (SDS) in dimethyl sulfoxide (DMSO) at room temperature and transferring a small volume of the mixture to toluene to form a precipitate. The tetragonal-phased CsPbCl 3 cubes and some rectangular blocks have square and rectangular {100}/{001} faces, while the cuboids have additional {101}/{110} edges. Variation in the amount of PbCl 2 transforms cubes to edgetruncated cuboids. Their absorption and emission band positions are nearly identical at 413−416 nm. Despite having relatively large sizes, the CsPbCl 3 cubes and edge-truncated cuboids display photoluminescence quantum yields of 6.9 and 2.9%, respectively. Remarkably, adding didecyldimethylammonium chloride (DDAC) surfactant to the reaction mixture leads to a 2−4.6-fold enhancement in the emission intensity. It is envisioned that other cesium lead halide crystals of tunable shapes can be synthesized by using the green reaction conditions.
Thermally activated delayed fluorescence (TADF) emitters are highly useful to achieve 100% internal quantum efficiency (IQE) and high external quantum efficiency (EQE) by reverse intersystem crossing. Herein, four sky-blue to...
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