3 research outputs found
Judicious Selection of Precursors with Suitable Chemical Valence State for Controlled Growth of Transition Metal Chalcogenides
Abstract Transition metal chalcogenides (TMCs) have attracted wide attentions as a class of promising material for both fundamental investigations and electronic applications due to their atomic thin thickness, dangling bondâfree surface, and excellent electronic properties. Specifically, TMCs show outstanding properties such as good thermal conductivity, robust mechanical properties, and extraordinary electronical characteristics, bestowing them utility in both fundamental research and applications. Recently, the development of postâMoore electronics based on TMCs calls for their largeâsize and singleâcrystal growth. However, researchers about synthesis usually focus on controlling several growth parameters (such as growth temperature, flow rate, and time). Herein, it is reported that the chemical valence states of transition metal precursors play an important role in controlling the lateral size and crystal quality for TMCs. The study discusses the valence statesâdependent growth mechanism for WS2 and MoS2 from four factors: evaporation temperature, skipping of reaction steps, atomic binding energy of the precursors, and formation energy. In addition, the asâgrown WS2 and MoS2 nanoflakes exhibit good photoelectric response properties. For EuS, the growth results are obviously different by using EuBr3 and EuBr2 as precursors. The studies provide a unique perspective and also new knowledge to controllably grow largeâsize and good crystal quality TMCs
Two-Step Growth of 2D OrganicâInorganic Perovskite Microplates and Arrays for Functional Optoelectronics
Two-dimensional
(2D) perovskites have recently attracted intensive
interest for their great stability against moisture, oxygen, and illumination
compared with their three-dimensional (3D) counterparts. However,
their incompatibility with a typical lithography process makes it
difficult to fabricate integrated device arrays and extract basic
optical and electronic parameters from individual devices. Here, we
develop a combination of solution synthesis and a gasâsolid-phase
intercalation strategy to achieve hexagonal-shaped 2D perovskite microplates
and arrays for functional optoelectronics. The 2D perovskite microplates
were achieved by first synthesizing the lead iodide (PbI<sub>2</sub>) microplates from an aqueous solution and then following with intercalation
via the vapor transport method. This method further allows us to synthesize
arrays of 2D perovskite microplates and create individual 2D perovskite
microplate-based photodetectors. In particular, chlorine (Cl) can
be efficiently incorporated into the microplates, resulting in significantly
improved performance of the 2D perovskite microplate-based photodetectors