Microlithography of hole transport layers for high-resolution organic light-emitting diodes with reduced electrical crosstalk
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Surfactant-induced hole concentration enhancement for highly efficient perovskite light-emitting diodes
It is widely acknowledged that constructing small injection barriers for balanced electron and hole injections is essential for light-emitting diodes (LEDs). However, in highly efficient LEDs based on metal halide perovskites, a seemingly large hole injection barrier is usually observed. Here we rationalize this high efficiency through a surfactant-induced effect where the hole concentration at the perovskite surface is enhanced to enable sufficient bimolecular recombination pathways with injected electrons. This effect originates from the additive engineering and is verified by a series of optical and electrical measurements. In addition, surfactant additives that induce an increased hole concentration also significantly improve the luminescence yield, an important parameter for the efficient operation of perovskite LEDs. Our results not only provide rational design rules to fabricate high-efficiency perovskite LEDs but also present new insights to benefit the design of other perovskite optoelectronic devices.
Efficient and stable near-infrared InAs quantum dot light-emitting diodes
Visible quantum dot light-emitting diodes have satisfied commercial display requirements. However, near-infrared counterparts considerably lag behind due to the inferior quality of near-infrared quantum dots and limitations in device architecture suitable for near-infrared electroluminescence. Here, we present an efficient strategy using zinc fluoride to balance ZnSe shell growth across different core quantum dot facets, producing highly regular InAs/InP/ZnSe/ZnS quantum dots with near-unity quantum yield. Moreover, we develop a method of in-situ photo-crosslinking blended hole-transport materials for accurate energy level modulation. The crosslinked hole-transport layers enhance hole transfer to the emitting layer for balanced carrier dynamics in quantum dot light-emitting diodes. The resulting near-infrared quantum dot light-emitting diodes exhibit a peak external quantum efficiency of 20.5%, a maximum radiance of 581.4 W sr−1 m−2 and an operational half-lifetime of 550 h at 50 W sr−1 m−2. This study represents a step towards practical application of near-infrared quantum dot light-emitting diodes.
Behavioral and neurophysiological effects of electrical stunning on zebrafish larvae
Two methods dominate the way that zebrafish larvae are euthanized after experimental procedures: anesthetic overdose and rapid cooling. Although MS-222 is easy to apply, this anesthetic takes about a minute to act and fish show aversive reactions and interindividual differences, limiting its reliability. Rapid cooling kills larvae after several hours and is not listed as an approved method in the relevant European Union directive. Electrical stunning is a promising alternative euthanasia method for zebrafish but has not yet been fully established. Here we characterize both behavioral and neurophysiological effects of electrical stunning in 4-day-old zebrafish larvae. We identified the electric field characteristics and stimulus duration (50 V/cm alternating current for 32 s) that reliably euthanizes free-swimming larvae and agarose-embedded larvae with an easy-to-implement protocol. Behavioral analysis and calcium neurophysiology show that larvae lose consciousness and stop responding to touch and visual stimuli very quickly (<1 s). Electrically stunned larvae no longer show coordinated brain activity. Their brains instead undergo a series of concerted whole-brain calcium waves over the course of many minutes before the cessation of all brain signals. Consistent with the need to implement the 3R at all stages of animal experimentation, the rapid and reliable euthanasia achieved by electrical stunning has potential for refinement of the welfare of more than 5 million zebrafish used annually in biomedical research worldwide.
Innovating beyond electrophysiology through multimodal neural interfaces
Neural circuits distributed across different brain regions mediate how neural information is processed and integrated, resulting in complex cognitive capabilities and behaviour. To understand dynamics and interactions of neural circuits, it is crucial to capture the complete spectrum of neural activity, ranging from the fast action potentials of individual neurons to the population dynamics driven by slow brain-wide oscillations. In this Review, we discuss how advances in electrical and optical recording technologies, coupled with the emergence of machine learning methodologies, present a unique opportunity to unravel the complex dynamics of the brain. Although great progress has been made in both electrical and optical neural recording technologies, these alone fail to provide a comprehensive picture of the neuronal activity with high spatiotemporal resolution. To address this challenge, multimodal experiments integrating the complementary advantages of different techniques hold great promise. However, they are still hindered by the absence of multimodal data analysis methods capable of providing unified and interpretable explanations of the complex neural dynamics distinctly encoded in these modalities. Combining multimodal studies with advanced data analysis methods will offer novel perspectives to address unresolved questions in basic neuroscience and to develop treatments for various neurological disorders.
Anthrone/XLPE: an adaptive charge capture intelligent insulation material for advanced electric power transmission
The degradation of electrical insulation is mainly attributed to local defects. Although incorporating organic small molecules into dielectric polymers promotes the insulation strength, accurate suppression of defect development is a long-term and formidable challenge. Here we utilize the adaptive charge capture methodology to achieve precise defect suppression, leading to a 123% increase in the initiation voltage of electrical trees in anthrone/cross-linked polyethylene, significantly outperforming existing dielectric polymers and polymer composites. A significant observation is the confinement of charge at the interface between the anode and cross-linked polyethylene in anthrone/cross-linked polyethylene, generating a reverse inherent electric field near the interface and reducing the internal electric field strength of cross-linked polyethylene by up to 18%. These findings not only open avenues for further exploration of materials for ultra-high voltage cables but also play a crucial role in the commercialization and practical application of organic semiconductors in insulation dielectrics.
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