Upconversion control: Applying a relatively low bias voltage to an epitaxial lanthanide‐doped BaTiO3 thin film results in a significant enhancement of the upconversion emission. Moreover, the photoluminescence (PL) intensity can be modulated with an ac electric field (see picture). This approach provides a real‐time and dynamic way to control photoluminescence.

References and links properties of BaTiO3 and SrTiO3 nanoparticles," J.

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Hydrogen bonding (HB) universally exists in CHON-containing energetic materials (EMs) and significantly influences their structures, properties, and performances. As time proceeds, some new types of EMs such as energetic cocrystals (ECCs) and energetic ionic salts (EISs) are thriving currently and richening insight into the HB of EMs, and these are reviewed in this article as well. The intramolecular HB mostly exists in stable molecules while seldom in less stable molecules; weak and abundant HBs dominate intermolecular interactions and consolidate crystal packing. For ECCs with neutral heterogeneous molecules, intermolecular HBs serve as one of the strategies for crystal design. In comparison, the HBs in EISs are greatly strengthened as their polarity significantly increases with ionization. A strong intramolecular HB usually enhances molecular stability with large π-bonds and packing coefficients and facilitates reversible H transfer, which is advantageous for low mechanical sensitivity. The intermolecular HB-aided π–π stacking that favors low mechanical sensitivity is observed in all three kinds of EMs, including traditional EMs with neutral homogeneous molecules, ECCs with neutral heterogeneous molecules, and EISs. However, a strong intermolecular HB in an EM causes a ready intermolecular H transfer, thereby worsening thermal stability. Thus, the influence of HBs on the stability of EMs can go both ways, and there should be a balance when new HB-containing EMs are designed.

Artificial optoelectronic synapses with both electrical and light‐induced synaptic behaviors have recently been studied for applications in neuromorphic computing and artificial vision systems. However, the combination of visual perception and high‐performance information processing capabilities still faces challenges. In this work, the authors demonstrate a memristor based on 2D bismuth oxyiodide (BiOI) nanosheets that can exhibit bipolar resistive switching (RS) performance as well as electrical and light‐induced synaptic plasticity eminently suitable for low‐power optoelectronic synapses. The fabricated memristor exhibits high‐performance RS behaviors with a high ON/OFF ratio up to 105, an ultralow SET voltage of ≈0.05 V which is one order of magnitude lower than that of most reported memristors based on 2D materials, and low power consumption. Furthermore, the memristor demonstrates not only electrical voltage‐driven long‐term potentiation, depression plasticity, and paired‐pulse facilitation, but also light‐induced short‐ and long‐term plasticity. Moreover, the photonic synapse can be used to simulate the “learning experience” behaviors of human brain. Consequently, not only the memristor based on BiOI nanosheets shows ultra‐low SET voltage and low‐power consumption, but also the optoelectronic synapse provides new material and strategy to construct low‐power retina‐like vision sensors with functions of perceiving and processing information.