Abstract2D inorganic bimolecular crystals, consisting of two different inorganic molecules, are expected to possess novel physical and chemical properties due to the synergistic effect of the individual components. However, 2D inorganic bimolecular crystals remain unexploited because of the difficulties in preparation arising from non‐typical layered structures and intricate intermolecular interactions. Here, the synthesis of 2D inorganic bimolecular crystal SbI3·3S8 nanobelts via a facile vertical microspacing sublimation strategy is reported. The as‐synthesized SbI3·3S8 nanobelts exhibit strong in‐plane anisotropy of phonon vibrations and intramolecular vibrations as well as show anisotropic light absorption with a high dichroism ratio of 3.9. Furthermore, it is revealed that the second harmonic generation intensity of SbI3·3S8 nanobelts is highly dependent on the excitation wavelength and crystallographic orientation. This work can inspire the growth of more 2D inorganic bimolecular crystals and excite potential applications for bimolecular optoelectronic devices.
P-n photovoltaic junctions are essential building blocks for optoelectronic devices for energy conversion. However, this photovoltaic efficiency has almost reached its theoretical limit. Here, a brand-new excitonic photovoltaic effect in 2D CsPbBr 3 /CdS heterostructures is revealed. These heterostructures, synthesized by epitaxial growth, display a clean interface and a strong interlayer coupling. The excitonic photovoltaic effect is a function of both the built-in equilibrium electrical potential energy and the chemical potential energy, which is generated by the significant concentration gradient of electrons and holes at the heterojunction interface. Excitingly, this novel photovoltaic effect results in a large open-circuit voltage of 0.76 V and a high power conversion efficiency of 17.5%. In addition, high photodetection performance, including a high photoswitch ratio (I light /I dark) of 10 5 and a fast response rate of 23 µs are obtained. These findings provide a new platform for photovoltaic applications.
Two-dimensional (2D) ferroelectrics have attracted intensive attention. However, the 2D ferroelectrics remain rare, and especially few of them represent high ferroelectric transition temperature (T C), which is important for the usability of ferroelectrics. Herein, CuCrS2 nanoflakes are synthesized by salt-assisted chemical vapor deposition and exhibit switchable ferroelectric polarization even when the thickness is downscaled to 6 nm. On the contrary, a CuCrS2 nanoflake shows a T C as high as ∼700 K, which can be attributed to the robust tetrahedral bonding configurations of Cu cations. Such robustness can be further clarified by a theoretically predicted high order–disorder transition barrier and structure evolution from 600 to 800 K. Additionally, the interlocked out-of-plane (OOP) and in-plane (IP) ferroelectric domains are observed and two kinds of devices based on OOP and IP polarizations are demonstrated.
2D ternary materials exhibit great promise in the field of polarization‐sensitive photodetectors due to the low‐symmetry crystal structure. However, the realization of ternary material growth is still a huge challenge because of the complex reaction process. Here, for the first time, 2D ternary In2SnS4 flakes are obtained via synergistic additive of salt and molecular sieve‐assisted chemical vapor deposition. Raman vibration mode of In2SnS4 flakes exhibits polarization‐dependent properties. The polarization‐resolved absorption spectroscopy and azimuth‐dependent reflectance difference microscopy further confirm its anisotropy of in‐plane optical absorption and reflection. Besides, the In2SnS4 flake based device on mica shows ultrafast rising and decay rates of ≈20 and 20 µs. Impressively, In2SnS4 flake based phototransistor demonstrates giant gate‐tunable polarization‐sensitive photoresponse: the dichroic ratio can be adjusted in the range of 1.13–1.70 with gate voltage varying from −35–35 V. This work provides an effective means for modulating the polarization‐sensitive photoresponse, which may significantly promote the research progress of polarization‐sensitive photodetectors.
There has been a renewed interest in 2D metal chalcogenide heterostructures (2DMCHs) in the context of their exceptional optoelectronic properties and potential for a wide variety of practical applications. However, the controllable synthesis of 2DMCHs remains a huge challenge. Recently, chemical vapor deposition (CVD) has been proposed to be an efficient way to realize high‐quality, large‐scale, and layer‐controllable 2D materials and has also shown high feasibility in 2DMCHs. Here, the latest controllable CVD growth strategies of 2DMCHs are introduced. The designed growth techniques mainly focus on three vital factors in CVD: source supply, mass transport, and substrate engineering. Then, the emerging novel applications of 2DMCHs are also systematically reviewed with particular attention to memory, infrared photodetector, and moiré superlattice, which have demonstrated significant progress in recent years. Finally, future opportunities and remaining challenges concerning the developments of 2DMCHs are presented.
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