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Multimaterial emission layer (EML) with host and dopant is known for its advantages in efficiency and lifetime for organic light‐emitting diodes (OLEDs). However, as the compositions and the mixing ratio in the EML diversify, complex device physics and photophysics and complicated fabrication processes become challenging issues. Herein, a new concept to integrate exciton donor (host) and acceptor (dopant) into a single emitting molecule is suggested. 9‐(8,9,10,11‐Tetradeuterospiro[benzo[de]anthracene‐7,9′‐fluoren]‐2'‐yl)‐9H‐carbazole (SBAF‐Cz) and 8,9,10,11‐tetradeutero‐N‐(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐N‐phenylspiro[benzo[de]anthracene‐7,9′‐fluoren]‐3‐amine (FPA‐SBAF) are used as host and dopant, respectively. By integrating two units, 8,9,10,11‐tetradeutero‐2′‐(9H‐carbazol‐9‐yl)‐N‐(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐N‐phenylspiro[benzo[de]anthracene‐7,9′‐fluoren]‐3‐amine (FPA‐SBAF‐Cz) is synthesized, and photophysical and electrical properties are characterized. Density functional theory and experimental results consistently reveal that SBAF‐Cz and FPA‐SBAF are photophysically and electrically independent. The electrical properties of FPA‐SBAF‐Cz behave independently, while the photophysical properties are the sum of those of SBAF‐Cz and FPA‐SBAF, which is attributed to the zero radius of intramolecular energy transfer (ZRIET) between donor and acceptor in FPA‐SBAF‐Cz. The single‐component blue OLED with FPA‐SBAF‐Cz exhibits a maximum external quantum efficiency of 4.18%, which is higher than those of OLEDs with SBAF‐CZ:FPA‐SBAF multicomponent EMLs. Surprisingly, the device lifetime to 50% decrease from initial luminance is 114 h in FPA‐SBAF‐Cz OLED, which is 2.2 times longer than that of SBAF‐Cz:FPA‐SBAF OLEDs. [ABSTRACT FROM AUTHOR]

We analyzed the degradation mechanism by deteriorating the exciplex host‐based phosphorescent organic light‐emitting diodes (PhOLEDs) while repeatedly applying voltages in the range of several nA to mA. To identify the most significant degradation factors represented by bleaching, quenching, and charge imbalance, the degradation process was described from various perspectives by the capacitance (C)‐voltage (V) curves (CV), and magneto‐electroluminescence (MEL). Comparing the MEL of the non‐doped and the doped devices, the bleaching of the dopant was confirmed as degradation progressed. Since the highest occupied molecular orbital (HOMO) of the dopant aligns with that of the hole‐transporting layer, the injected holes are easily trapped. As a result, the trap‐induced Shockley‐Read Hall recombination became dominant. Thus, it was identified that the bleaching of the dopant itself acts as the major degradation factor. [ABSTRACT FROM AUTHOR]

Commercialization of energy conversion technologies, such as water electrolysis or fuel cells, has become a common prioritized goal in academia and industry due to the accelerated environmental crisis caused by the rapid increase in demand for fossil fuel‐based energy resources. However, these state‐of‐the‐art technologies require the use of expensive noble metal‐based electrocatalysts, which significantly undermine the feasibility of their commercial success. The introduction of less expensive elements into the noble metal‐based electrocatalysts, namely, doping, has become common in nanocatalysis research because of the lower catalyst preparation costs. Interestingly, recent studies have revealed additional roles of dopants in noble metal catalysts; doping can enhance the catalytic activity and selectivity by modulating the band structure, optimizing the surface energy of the catalysts, controlling the binding strength of adsorbates, and thus affecting the reaction kinetics. Dopants can also intervene in the nanocrystal growth mechanism, leading to shape‐ and phase‐controlled nanocrystals. This review discusses the great versatility of dopants in nanoparticle‐based catalysis in all aspects, from nanocrystal growth to nanocatalyst performance. The future challenges and outlook for dopants in nanocrystals and their applications are further discussed. [ABSTRACT FROM AUTHOR]

Dissolution of Ir oxides in Ir‐based catalysts, which is closely linked to the catalyst activity and stability toward the oxygen evolution reaction (OER) in acidic media, is a critical unresolved problem in the commercialization of water electrolysis. Doping foreign elements into the Ir oxides can accomplish an optimal combination of Ir oxidation states that is conducive to the leaching‐resistance of active catalytic sites. Here, it is reported that Pt doping into IrOx‐based nanoframe is beneficial in both terms of activity and stability. The Pt‐doped IrOx‐based nanoframe achieves the mass activity of 0.644 A mg−1Ir+Pt at 1.53 VRHE, which is 15‐fold higher than that of the commercial IrO2. During the accelerated durability test, the IrIV‐to‐IrIII ratio of 5 is maintained in the presence of Pt dopant to effectively mitigate the degradation of Ir catalyst, leading to the superb catalyst durability in acidic media. [ABSTRACT FROM AUTHOR]

• p-host and fluorescent dopant was seamlessly integrated into a single molecule. • Non-conventional exciplex formed between fused p-host and n-host. • ZETPLEX, an extremely efficient energy transfer within fused p-host and n-host. A multi-component emissive layer (EML) composed of a mixture of p- and n-type hosts and a dopant is a widely used structure in organic light-emitting diodes (OLEDs) due to its high efficiency and operational stability. However, multi-component EML devices impose limitations such as difficulty in accurately controlling the mixing ratio and profiles in the manufacturing process, high costs, and complexity in the photophysical properties of the components. In this paper, a p-type host fused with a blue fluorescent dopant, 5,9-di([1,1′-biphenyl]-2-yl)-2′-(9H-carbazole-9-yl)3,7-dimethyl-5,5a,5a1,9,9a,16a-hexahydrospiro[5,9-diaza-16b-boraindeno[2,1-b]naphtho[1,2,3-fg]anthracene-11,9′-fluorene] (DABNA-Spiro-Cz), was designed and successfully synthesized to construct a novel EML structure. Completely fused within DABNA-Spiro-Cz, the p-type host and blue fluorescent dopant can independently perform their respective roles. An exciplex is formed between n-type host and p-type host unit in the DABNA-Spiro-Cz molecule and its energy is effectively transferred to the blue fluorescent dopant unit in DABNA-Spiro-Cz. In other words, a degree of freedom is earned from a conventional 3-component exciplex-dopant system. A high external quantum efficiency of 14.9 % was achieved thanks to " z ero-radius of intramolecular e nergy t ransfer in exci plex (ZETPLEX)" system, which is completely non-conventional and novel. We believe the ZETPLEX mechanism opens a new era of designing emissive materials and paves a new way of constructing a novel EML and device architecture for highly efficient OLEDs. [ABSTRACT FROM AUTHOR]

• Intermolecular interaction between host and deep blue Pt complex utilized in WOLEDs. • By varying the ratio of n-type host, a wide range of colors was achieved. • Highly efficient WOLEDs were realized with a single deep blue Pt(II) complex. Previous studies on white organic light-emitting diodes (WOLEDs) using a single Pt dopant relied on square-planar Pt complexes, exhibiting various emission characteristics due to ligand-centered π-π interactions. However, this approach limits the range of the materials selections to those with excimer or aggregation-induced emission (AIE) properties. In this study, a new method for creating WOLEDs with a single Pt dopant is proposed. We observed the emergence of an intermolecular interaction, specifically the formation of an exciplex due to π-π interaction between the n-host (ET) and the Pt complex, leading to a low-energy yellow emission. By varying the mixing ratio of ET and Pt complex, a spectrum of emissions ranging from pure blue to yellow was achievable. Consequently, we constructed 3-stack tandem devices, leveraging color variations based on the ET:Pt ratio. As a result, we successfully achieved a cool white emission with a Color Rendering Index (CRI) of 66.7, International Commission on Illumination (CIE) coordinates of (0.294, 0.380). Additionally, through optimization of the device structure, external quantum efficiency (EQE) was enhanced from 18.3% to 21.9%. This novel and simple device architecture adjusting intermolecular interaction based on molecular geometry between ET and Pt(II) complex provides a solution to materials limitations in WOLEDs. [ABSTRACT FROM AUTHOR]