Recently, impressive external quantum efficiencies (EQEs) exceeding 20% are obtained for green, red, and near-infrared perovskitebased LEDs (PeLEDs) through the efforts of perovskite material optimization and device architecture design. [8-10] These achievements firmly prompt the potential applications of PeLEDs in display and illumination fields. However, compared with the efficient PeLEDs, there is only moderate performance reported for blue PeLEDs, [11-18] which undoubtedly restrict PeLED applications in full-color displays and white-light illumination. Thus, the breakthroughs of the device performance are urgently required for blue PeLEDs. Substantial efforts have been made in the past several years to obtain blue perovskite emitters, such as perovskite nanocrystals (NCs), [19-25] 2D perovskite nanoplatelets, [26-32] and quasi-2D perovskites. [33-39] In particular, the quasi-2D perovskites are rising as efficient luminescent materials for highly performed blue PeLEDs due to the cascade energy landscape for efficient exciton transfer and the subsequent radiative recombination. Typically, the quasi-2D perovskites have a formula of B 2 (APbBr 3) n−1 PbBr 4 , While there has been extensive investigation into modulating quasi-2D perovskite compositions in light-emitting diodes (LEDs) for promoting their electroluminescence, very few reports have studied approaches involving enhancement of the energy transfer between quasi-2D perovskite layers of the film, which plays very important role for achieving high-performance perovskite LEDs (PeLEDs). In this work, a bifunctional ligand of 4-(2-aminoethyl)benzoic acid (ABA) cation is strategically introduced into the perovskite to diminish the weak van der Waals gap between individual perovskite layers for promoting coupled quasi-2D perovskite layers. In particular, the strengthened interaction between coupled quasi-2D perovskite layers favors an efficient energy transfer in the perovskite films. The introduced ABA can also simultaneously passivate the perovskite defects by reducing metallic Pb for less nonradiative recombination loss. Benefiting from the advanced properties of ABA incorporated perovskites, highly efficient blue PeLEDs with external quantum efficiency of 10.11% and a very long operational stability of 81.3 min, among the best performing blue quasi-2D PeLEDs, are achieved. Consequently, this work contributes an effective approach for high-performance and stable blue PeLEDs toward practical applications. Metal halide perovskites have emerged as competitive candidates for the next-generation light-emitting diodes (LEDs) due to their excellent optical properties, such as tunable light emission color, high color purity, and high photoluminescence The ORCID identification number(s) for the author(s) of this article can be found under

semiconductor nanorods are important for numerous applications ranging from optics and electronics to biology, yet the direct synthesis of high-quality metal halide perovskite nanorods remains a challenge. Here, we develop an intermediate monomer reservoir synthetic strategy to realize the controllable growth of uniform and low-defect CsPbBr 3 perovskite nanorods. Intermediates composed of CsPb 2 Br 5 and Cs 3 In 2 Br 9 are obtained through the substitution of Pb 2+ with In 3+ cations in the template of CsPbBr 3 nanocubes and act as a precursor reservoir to gradually release monomers, ensuring both the slow growth rate and low defects of nanorods. We have used branched tris(diethylamino)phosphine as a ligand, which not only has unequal binding energies with different crystal faces to promote the orientation growth but also provides strong steric hindrance to shield the nanorods in solution. Because of minor amount of defects and an effective ligand passivation, in addition to significantly enhanced stability, the perovskite nanorods show a high photoluminescence quantum yield of up to 90% and exhibit a net mode gain of 980 cm −1 , the latter being a record value among all the perovskite materials. An extremely low amplified spontaneous emission threshold of 7.5 μJ cm −2 is obtained under excitation by a nanosecond laser, which is comparable to that obtained using femtosecond lasers in other recent studies.

3D ternary nickel iron sulfide microflowers with a hierarchically porous structure have been directly grown on Ni foam via a convenient two-step method for efficient bifunctional water splitting.

Rapid advances in wearable electronics and mechno-sensational human-machine interfaces impose great challenges in developing flexible and deformable tactile sensors with high efficiency, ultra-sensitivity, environment-tolerance, and self-sustainability. Herein, a tactile hydrogel sensor (THS) based on micro-pyramid-patterned double-network (DN) ionic organohydrogels to detect subtle pressure changes by measuring the variations of triboelectric output signal without an external power supply is reported. By the first time of pyramidal-patterned hydrogel fabrication method and laminated polydimethylsiloxane (PDMS) encapsulation process, the self-powered THS shows the advantages of remarkable flexibility, good transparency (≈85%), and excellent sensing performance, including extraordinary sensitivity (45.97 mV Pa −1 ), fast response (≈20 ms), very low limit of detection (50 Pa) as well as good stability (36 000 cycles). Moreover, with the LiBr immersion treatment method, the THS possesses excellent long-term hyper anti-freezing and anti-dehydrating properties, broad environmental tolerance (−20 to 60 °C), and instantaneous peak power density of 20 μW cm −2 , providing reliable contact outputs with different materials and detecting very slight human motions. By integrating the signal acquisition/process circuit, the THS with excellent self-power sensing ability is utilized as a switching button to control electric appliances and robotic hands by simulating human finger gestures, offering its great potentials for wearable and multi-functional electronic applications.

Quasi-two-dimensional (quasi-2D) perovskite is rising as a promising luminescent material for blue perovskite light-emitting diodes (PeLEDs). However, typical quasi-2D perovskites show a wide distribution of low-order phases and low efficiency owing to the inefficient energy transfer. Meanwhile, the defects and traps generated during the perovskite crystallization increase nonradiative recombination, further aggravating the external quantum efficiency (EQE). Herein, we demonstrate a unique quasi-2D perovskite with low-order phase suppression and defect passivation for efficient energy transfer and light emission by incorporating a 2D perovskite and an excess ammonium salt into the quasi-2D perovskite solution. By optimizing the new class of quasi-2D perovskite, we achieve blue PeLEDs with the brightness of 1765 cd m–2, EQE of 7.51%, low turn-on voltage of 3.07 V, and long operation lifetime of 3961 s under constant driving current without any shift of the electroluminescence spectra. The work contributes to promoting efficient and stable blue PeLEDs.