Organic light emitting diodes (OLEDs) displaying a wide range of emission colors with emission peaks from 450 to 665 nm using a single emitting material, avobenzone boron difluoride (AVB-BF 2 ), are This article is protected by copyright. All rights reserved. 2 reported. Color tuning is achieved by controlling the aggregation of AVB-BF 2 and the formation of a "triadic" exciplex of an AVB-BF 2 dimer and a host molecule. Various electroluminescent devices containing AVB-BF 2 cover the whole visible light spectrum and a white-emitting device with CIE coordinates of (0.35, 0.37) is obtained with a single emitting material in a single emissive layer.Furthermore, an exceptionally high external quantum efficiency of nearly 13% is achieved for a greenemitting OLED because AVB-BF 2 exhibits thermally activated delayed fluorescence by forming the exciplex.

are thought to limit the performance of phosphorescent OLEDs and TADF OLEDs. [10,11] During OLED operation, the triplet-polaron interaction causes undesirable efficiency roll-off (i.e., increased quenching of excited states at higher current densities) and degradation (e.g., increasing the number of molecules with some of their intramolecular bonds irreversibly dissociated), resulting in less emitted light. Understanding and managing exciton dynamics is therefore of great significance in the design of modern TADF OLEDs. [12,13] These internal nanoscale processes are often difficult to observe, so there is

White light-emitting diodes (WLEDs) based on copper iodides have attracted tremendous interest due to their broad emission and environmentally friendly nature. Cesium copper iodide is usually regarded as the emissive center in this type of LED. Here, we reveal that it is the in situ formed copper iodide complex, generated during the deposition of the electron transporting layer on cesium copper iodide films, that dominates the electroluminescence. It is also found that the narrow bandgap and widely distributed band-edge states of the complex facilitate the hole injection, resulting in low-voltage driving. Combining a modified hole injection layer to suppress the interfacial exciton quenching, an efficient broadband LED with a turn-on voltage of 2.3 V and a peak EQE of 4.6% was achieved. The driving voltages at 100 and 1000 cd m–2 are 2.9 and 4.9 V, respectively, both of which are the lowest among all reported Cu­(I) complex-based broadband WLEDs.

Low‐energy inverse photoelectron spectroscopy (LEIPS) and ultraviolet photoelectron spectroscopy (UPS) incorporated into the multitechnique XPS system were used to probe the ionization potential and the electron affinity of organic materials, respectively. By utilizing gas cluster ion beam (GCIB), in situ analyses and depth profiling of LEIPS and UPS were also demonstrated. The band structures of the 10‐nm‐thick buckminsterfullerene (C60) thin film on Au (100 nm)/indium tin oxide (100 nm)/glass substrate were successfully evaluated in depth direction.

We investigated the influence of vacuum chamber impurities on the lifetime of highly efficient TADF-based OLEDs. Batch-to-batch lifetime variations are clearly correlated with the results of contact angle measurements, which reflect the amount of impurities present in the chamber. Introduction of ozone gas can clean the impurities out of the vacuum chamber, reducing the contact angle to less than 10°. In the vacuum chamber of a new deposition system designed using resin-free vacuum components, various plasticizers and additive agents were initially detected by WTD-GC-MS analysis, but these impurities vanished after ozone gas cleaning. Devices fabricated in the new chamber exhibited lifetimes that are approximately twice those of OLEDs fabricated in a pre-existing chamber. These results suggest that impurities, particularly from plasticizers, in the vacuum chamber greatly influence the OLED lifetime.