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Optoelectronic memristors, which possess the potential capacities of in‐sensor computing, promote the development of highly efficient neuromorphic vision. In this work, a novel optoelectronic memristor based on chlorophyll (Chl) heterojunction is proposed, which consists of two types of Chl derivatives (zinc methyl 3‐devinyl‐3‐hydroxymethyl‐pyropheophorbide‐a and methyl 131‐deoxo‐131‐dicyanomethylene‐pyropheophorbide‐a). Chl heterojunction improves the optoelectronic performance of the device due to its ability to efficiently separate photogenerated electron‐hole pairs. The device exhibits the synaptic potentiation and inhibition behaviors under light stimulations of 430 and 730 nm, respectively, thus demonstrating the all‐optically modulated synaptic plasticity. The switching mechanism can be attributed to the photo‐ionization/deionization of oxygen vacancies at the zinc oxide (ZnO)/Chl interface. In addition, the image pre‐processing functions of contrast enhancement and noise reduction are implemented in a memristive array. In particular, the edge detection function has been implemented by utilizing reversible optical modulation, which highlights the object outline. The optoelectronic memristor based on the Chl heterojunction proposed here provides a promising foundation for advancing neuromorphic vision. [ABSTRACT FROM AUTHOR]

Elemental tellurium, a prototypical one‐dimensional van der Waals material, has recently been found to crystallize quickly from the liquid on a nanosecond timescale, yet the inherent mechanism is not clear. Here, by combining in situ high‐energy synchrotron radiation X‐ray diffraction with ab initio molecular‐dynamics simulation, it is found that trigonal crystalline Te completely melts into the liquid phase at 450 °C, and recrystallizes into the trigonal phase for temperatures lower than 380 °C without the formation of any other phase. This directly confirms the recent proposal of a crystal‐liquid‐crystal phase transition in this material underlying the observed electrical‐switching process. Atomic‐scale, melt‐quench computer simulations show that liquid Te is capable of crystallizing within a time of 25 ps in the vicinity of templating crystallization interfaces. This ultrafast crystallization ability of Te can be understood as being due to delayed Peierls distortions during a quench and therefore a high atomic mobility over a wide range of temperature. This finding opens the way to develop a crystal‐liquid‐crystal, phase‐transition‐based selector switch with an ultrafast switching speed. [ABSTRACT FROM AUTHOR]

The unique morphology of 2D van der Waals materials enables them to withstand large deformations and significant nonuniform strain, potentially inducing a strong flexoelectric effect. Despite the size‐dependent flexoelectric effect showing potential for modulating the optoelectronic performance of 2D van der Waals materials, it is far from being fully exploited owing to various challenges. Herein, the use of nanowires with different diameters as the bending media to fabricate 2D α‐In2Se3/β‐InSe heterojunctions with large curvatures of 0.1–1 µm−1 is proposed. The significant band alignment modulation in α‐In2Se3 resulting from the bending‐induced flexoelectric effect is verified through Kelvin probe force microscopy. The strain‐induced piezoelectric effect can be negated because of the weak vdW forces at the interface. The flexoelectric polarization in β‐InSe is screened via the accumulated electrons in the unilateral depleted heterojunction. Compared to the flat heterojunction, the curved heterojunction with an average curvature of 0.9 µm−1 shows 2.48‐fold and 7.62‐fold increases in open‐circuit voltage and zero‐biased responsivity, respectively. This study demonstrates the first successful modulation of photodetection in 2D heterojunctions by exploiting the flexoelectric effect, providing a new perspective for high‐performance 2D vdW optoelectronic devices. [ABSTRACT FROM AUTHOR]