Programmable Single‐Crystalline PbI₂ Microplate Arrays and Their Organic/Inorganic Heterojunctions

Abstract

Deterministic patterning of inorganic semiconducting micro-/nanostructures has laid the foundation for the on-chip integration of optoelectronic devices. However, it requires complicated equipment for thin-film deposition, lithography, and etching. Solution-processing bottom-up integration of micro-/ nanostructures has been extensively studied in organic semiconductors and nanoparticles, but solution-patternable inorganic single-crystalline micro-/nanostructures are still elusive. It is still challenging to control the crystallization of inorganic semiconductors in solution processes. Herein, an efficient strategy is developed to steer the crystallization of PbI 2 hexagonal microplates in capillary bridges. Evenly distributed mass and ordered microfluid in each capillary bridge are able to attain simultaneous manipulation of position, size, and crystallographic orientation. Complex patterns, including Latin characters, Arabic numeral characters, and mathematical symbols, are realized by positioning capillary bridges. Based on these high-quality PbI 2 microcrystals, high-performance photodetectors are demonstrated with a responsivity of 625 mA W −1 , an on-off ratio of 10 5 and response speeds of τ rise = 0.31 ms and τ decay = 0.17 ms. This technique also allows for the integration of PbI 2 microstructures with organic semiconductors to manufacture heterojunction arrays with efficient charge transfer. The strategy provides a perception to fabricate inorganic single-crystalline microarrays and heterostructures for integrated optoelectronics.

Edge Raman enhancement at layered PbI2 platelets induced by laser waveguide effect

“…The SAED pattern shown in figure 1(e) displays a bright diffraction spot and the hexagonal symmetry, in agreement with the hexagonal atom arrangement of PbI 2 . Our TEM results are consistent with those reported in the literature [21,22,[45][46][47][48]. Figure 1(f) shows the x-ray diffraction (XRD) pattern of PbI 2 platelets.…”

“…By comparing the peak positions with the standard PDF card (JCPDS: No. 07-0235) shown in the lower panel, the XRD pattern shows only (00l) diffraction peaks which is in good agreement with literatures reported [21,45,[48][49][50][51][52]. It can be concluded that the PbI 2 platelets show a 2H type PbI 2 crystal structure and prefer to have their (001) planes up [53].…”

Microspacing In-Air Sublimation Growth of Thickness-Controllable Lead Halide Crystal and the Morphology Evolution in Conversion to Perovskite

“…Among lead halides PbX 2 (X = Cl, Br, I), PbI 2 is a typical two-dimension layered semiconducting material, , which itself can be used as visible-light and high-energy ray detectors or as precursors to prepare perovskite materials. ,− It comprises a hexagonally close-packed layer of lead ion sandwiched between two layers of iodide ions with unit cell dimensions of a = 4.557 Å and c = 6.979 Å. Many efficient methods of melt growth, solution process, and vapor deposition could be used for the synthesis of PbI 2 . − For example, thin PbI 2 crystals have been grown using hot casting from a saturated PbI 2 solution, , or using the physical vapor deposition (PVD) method .…”

Low‐Dimensional Organic Crystals: From Precise Synthesis to Advanced Applications

“…Thus, to improve the crystal quality during solution patterning, it is necessary to simultaneously tune the nucleation position and the growth direction during the self-assembly of organic molecules; this has been achieved by controlling the surface chemical state and the geometry of the template. [148][149][150][151][152] Recently, Wu et al proposed the confined capillary liquids technique, which was based on superwetting interfaces and represents a milder and simpler procedure compared to the microfabrication approach, and it was also found to be suitable for the preparation of arrays and patterns of micro-nano crystal materials. [153] As shown in Figure 8a, they initially prepared micropillars with asymmetric wettability, including a lyophilic top and lyophobic sidewalls, which promoted the induced self-assembly of organic crystals.…”