Lead halide perovskites have received much attention in the field of optoelectronic devices. However, the environment-unfriendly nature and intrinsic instability of these perovskites hamper their commercial applications. In this work, one novel one-dimensional lead-free halide perovskite with high stability, CsCu 2 I 3 , was prepared via an antisolvent-assisted crystallization method. The prepared CsCu 2 I 3 bears a high exciton binding energy of ∼105 meV and a high photoluminescence quantum yield of 12.3%. We fabricated a deep ultraviolet photodetector based on a CsCu 2 I 3 film that is nearly blind to 405 nm visible light but is sensitive to 265 and 365 nm illumination. The device exhibits excellent reproducibility and a high I light /I dark ratio of 22 under 265 nm illumination. Furthermore, the responsivity, specific detectivity, and external quantum efficiency are as high as 22.1 mA/W, 1.2 × 10 11 Jones, and 10.3% under a light density of 0.305 mW/cm 2 , respectively. These findings demonstrate that CsCu 2 I 3 perovskites should have great potential for future optoelectronics.

Transition metal dichalcogenides (TMDs) (MX 2 , M = Mo or W, X = S, Se, or Te) have attracted intense interest for developing ultrascaled electronics and optoelectronics by virtue of their attractive 2D layered structures and unique physical properties that are absent in their bulk counterparts. [1][2][3][4][5] Monolayer semiconducting TMDs show sizable direct bandgaps, quantum confinement effects, large exciton binding energies and effective valley polarizations, which unveils widespread applications in field-effect transistors (FETs), photodetectors, light-emitting diodes, pumped lasers, solar cells, and valleytronic devices. [6][7][8][9][10] More excitingly, their 2D structures offer superior electrostatic controllability and exemptible short-channel effects, rendering TMDs promising candidates for future sub-10 nm complimentary metal-oxide-semiconductor (CMOS) devices. [5,11,12] The applications of exfoliated TMD flakes in building high-performance prototypes of electronics, photonics, and optoelectronics have already been demonstrated. [13][14][15][16] The exfoliated flakes, however, suffer from Monolayer MoTe 2 , with the narrowest direct bandgap of ≈1.1 eV among Mo-and W-based transition metal dichalcogenides, has attracted increasing attention as a promising candidate for applications in novel near-infrared electronics and optoelectronics. Realizing 2D lateral growth is an essential prerequisite for uniform thickness and property control over the large scale, while it is not successful yet. Here, layer-by-layer growth of 2 in. wafer-scale continuous monolayer 2H-MoTe 2 films on inert SiO 2 dielectrics by molecular beam epitaxy is reported. A single-step Mo-flux controlled nucleation and growth process is developed to suppress island growth. Atomically flat 2H-MoTe 2 with 100% monolayer coverage is successfully grown on inert 2 in. SiO 2 /Si wafer, which exhibits highly uniform in-plane structural continuity and excellent phonon-limited carrier transport behavior. The dynamics-controlled growth recipe is also extended to fabricate continuous monolayer 2H-MoTe 2 on atomic-layer-deposited Al 2 O 3 dielectric. With the breakthrough in growth of wafer-scale continuous 2H-MoTe 2 monolayers on device compatible dielectrics, batch fabrication of high-mobility monolayer 2H-MoTe 2 field-effect transistors and the three-level integration of vertically stacked monolayer 2H-MoTe 2 transistor arrays for 3D circuitry are successfully demonstrated. This work provides novel insights into the scalable synthesis of monolayer 2H-MoTe 2 films on universal substrates and paves the way for the ultimate miniaturization of electronics.

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In recent years, it has been reported that using ligands modification to passivate the surface is one reasonable approach to improve the optical properties and stability of perovskite quantum dots (QDs). However, a simple and effective way to diminish the aggregation phenomenon of perovskite QDs is still challenging. Herein, a ligand‐engineering strategy is adopted to fabricate CsPbBr3 QDs by applying a shorter capping ligand octylamine (OLA) to replace the commonly used long ligand oleylamine (OAm). After the ligand modification, the photoluminescence quantum yield of CsPbBr3 QDs is enhanced from 62.4% to 91.3%. No aggregation or degradation phenomenon can be observed in solution even after being exposed to the air for 100 days. Moreover, the OLA‐CsPbBr3 QDs film can keep 96.8% of initial photoluminescence intensity even when stored under ambient condition for 5 weeks. Furthermore, the stimulated emission performance is investigated in terms of amplified spontaneous emission (ASE), and the ASE threshold of OLA‐CsPbBr3 QDs is only 24% of the OAm‐CsPbBr3 QDs threshold, and the ASE photostability is also enhanced. All the results suggest that the OLA ligand modification is an available strategy to improve the properties of CsPbBr3 QDs and to shed light on the potential practical applications for photoelectric devices.

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Herein, we employed lead-free Cs3Cu2I5 perovskite films as the functional layers to construct Al/Cs3Cu2I5/ITO memory devices and systematically investigated the impact on the corresponding resistive switching (RS) performance via adding different amounts of hydroiodic acid (HI) in Cs3Cu2I5 precursor solution. The results demonstrated that the crystallinity and morphology of the Cs3Cu2I5 films can be improved and the resistive switching performance can be modulated by adding an appropriate amount of HI. The obtained Cs3Cu2I5 films by adding 5 μL HI exhibit the fewest lattice defects and flattest surface (RMS = 13.3 nm). Besides, the memory device, utilizing the optimized films, has a low electroforming voltage (1.44 V), a large on/off ratio (∼65), and a long retention time (104 s). The RS performance impacted by adding HI, providing a scientific strategy for improving the RS performance of iodine halide perovskite-based memories.

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