The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.

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A series of host materials 1-7 containing various heterocyclic cores, like pyridine, pyrimidine, and pyrazine, were developed for RGB phosphorescent organic light-emitting diodes (OLEDs). Their energy levels can be tuned by the change of heterocyclic cores and their nitrogen atom orientations, and decrease of singlet-triplet exchange energy (ΔE ST ) was achieved with introducing one or two nitrogen atoms into the central arylene; this is also consistent with density functional theory calculations. Their carrier mobilities can also be tuned by the choice of heterocyclic cores, giving improved bipolarity compared with that without any heterocyclic cores. Due to the high triplet energy level of the developed host materials, well confinement of triplet excitons of blue emitter iridium(III) bis(4,6-(difluorophenyl)pyridinato-N,C 2 0 ) picolinate (FIrpic) was achieved except for 7 due to its low E T . In contrast, triplet energy can be well confined on green emitter fac-tris-(2-phenylpyridine) iridium (Ir(PPy) 3 ) and red emitter tris(1-phenylisoquinolinolato-C 2 ,N)iridium-(III) (Ir(piq) 3 ) for all the hosts, giving comparable lifetime (τ), photoluminescent quantum efficiency (η PL ), and radiative and nonradiative rate constants (k r and k nr ). Highly efficient blue and green phosphorescent OLEDs were achieved for 2, exhibiting one of the highest ever efficiencies to date, especially at much brighter luminance for lighting applications. In comparison, the highest efficiencies hitherto were achieved for the red phosphorescent OLED based on 6, which can be attributed to its lower-lying LUMO level and the smallest ΔE ST , giving improved electron injection and carrier balance. Different from the blue and green phosphorescent OLEDs based on FIrpic and Ir(PPy) 3 , the host materials with lower-lying LUMO levels seem to be better hosts for a red emitter Ir(piq) 3 , achieving improved efficiency and reduced efficiency roll-off at high current density.

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Single-atom catalysts (SACs) with 100% active sites have excellent prospects for application in the oxygen evolution reaction (OER). However, further enhancement of the catalytic activity for OER is quite challenging, particularly for the development of stable SACs with overpotentials <180 mV. Here, we report an iridium single atom on Ni 2 P catalyst (Ir SA -Ni 2 P) with a record low overpotential of 149 mV at a current density of 10 mA•cm −2 in 1.0 M KOH. The Ir SA -Ni 2 P catalyst delivers a current density up to ∼28-fold higher than that of the widely used IrO 2 at 1.53 V vs RHE. Both the experimental results and computational simulations indicate that Ir single atoms preferentially occupy Ni sites on the top surface. The reconstructed Ir−O−P/Ni−O−P bonding environment plays a vital role for optimal adsorption and desorption of the OER intermediate species, which leads to marked enhancement of the OER activity. Additionally, the dynamic "top-down" evolution of the specific structure of the Ni@Ir particles is responsible for the robust single-atom structure and, thus, the stability property. This Ir SA -Ni 2 P catalyst offers novel prospects for simplifying decoration strategies and further enhancing OER performance.

Electrosynthesis of hydrogen peroxide (H 2 O 2 ) through oxygen reduction reaction (ORR) is an environmentfriendly and sustainable route for obtaining a fundamental product in the chemical industry. Co−N 4 single-atom catalysts (SAC) have sparkled attention for being highly active in both 2e − ORR, leading to H 2 O 2 and 4e − ORR, in which H 2 O is the main product. However, there is still a lack of fundamental insights into the structure−function relationship between CoN 4 and the ORR mechanism over this family of catalysts. Here, by combining theoretical simulation and experiments, we unveil that pyrrole-type CoN 4 (Co−N SAC Dp ) is mainly responsible for the 2e − ORR, while pyridine-type CoN 4 catalyzes the 4e − ORR. Indeed, Co−N SAC Dp exhibits a remarkable H 2 O 2 selectivity of 94% and a superb H 2 O 2 yield of 2032 mg for 90 h in a flow cell, outperforming most reported catalysts in acid media. Theoretical analysis and experimental investigations confirm that Co−N SAC Dp �with weakening O 2 /HOO* interaction�boosts the H 2 O 2 production.

Electrochemical CO 2 reduction is a promising way to mitigate CO 2 emissions and close the anthropogenic carbon cycle. Among products from CO 2 RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C 2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C−C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C−C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric−thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature enhancement at the tips compared with bare copper nanoneedles experimentally), resulting in an improved C 2 Faradaic efficiency of over 86% at a partial current density of more than 250 mA cm −2 and a record-high C 2 turnover frequency of 11.5 ± 0.3 s −1 Cu site −1 . Combined with its low cost and scalability, the electric−thermal strategy for a state-of-the-art catalyst not only offers new insight into improving activity and selectivity of value-added C 2 products as we demonstrated but also inspires advances in efficiency and/or selectivity of other valuable electro-/photocatalysis such as hydrogen evolution, nitrogen reduction, and hydrogen peroxide electrosynthesis.

Electrochemical production of hydrogen peroxide (H 2 O 2 )t hrough two-electron (2 e À )o xygen reduction reaction (ORR) is an on-site and clean route.O xygen-doped carbon materials with high ORR activity and H 2 O 2 selectivity have been considered as the promising catalysts,h owever,t here is still alackofdirect experimental evidence to identify true active sites at the complex carbon surface.H erein, we propose ac hemicalt itration strategy to decipher the oxygen-doped carbon nanosheet (OCNS 900 )c atalyst for 2e À ORR. The OCNS 900 exhibits outstanding 2e À ORR performances with onset potential of 0.825 V( vs.R HE), mass activity of 14.5 Ag À1 at 0.75 V( vs.R HE) and H 2 O 2 production rate of 770 mmol g À1 h À1 in flow cell, surpassing most reported carbon catalysts.Through selective chemical titration of C = O, C À OH, and COOH groups,wefound that C = Ospecies contributed to the most electrocatalytic activity and were the most active sites for 2e À ORR, which were corroborated by theoretical calculations.