Layer‐Defining Strategy to Grow Two‐Dimensional Molecular Crystals on a Liquid Surface down to the Monolayer Limit

Abstract

Two‐dimensional molecular crystals (2DMCs) open a new door for the controllable growth of 2D materials by molecular design with a energy gap and solution processability. However, the growth of 2DMCs with defined molecular layers remains full of challenges. Herein, we report a novel method to produce various 2DMCs with a defined number of molecular layers. When the surface tension and viscosity are tuned to control the spreading of the solution on the liquid surface, large‐area quasi‐freestanding 2DMCs from bulk size down to the monolayer limit are obtained, which makes it possible to probe the intrinsic layer‐dependent optoelectronic properties of organic semiconductors down to the physical limit, and paves the way for the application of 2DMCs in new optoelectronic devices and technologies.

Spin injection and transport in single-crystalline organic spin valves based on TIPS-pentacene

“…Glycerol was chosen as a liquid substrate. The high surface tension together with the high viscosity of glycerol can promote the spreading and fix the position of the solution during evaporation, which was favorable for the production of thin and large-area single crystals [35]. TIPS-pentacene, a high-mobility material for organic FETs (OFETs), was chosen as the architype organic semiconductor.…”

“…Recently, we have developed a strategy to grow thin and large-area organic single crystals with different thick-nesses on glycerol surface [35]. These semi-freestanding crystals on liquid surfaces can be transferred to arbitrary substrates to construct various devices.…”

Two-dimensional molecular crystals: a review

“…(a) Drain-source current response of 1L and ML OFET sensors under different concentrations of NH 3 [36]; mechanisms for NH 3 sensing in (b) 1L and (c) ML OFET sensors [36]; (d) the sensitivity of 1L-OFET-based gas sensors [59]; (e) the current responses of 1L-OFET-based gas sensors [59] (color online). (e) 性 能参数与晶体层数的关系 [42] (网络版彩图) 全耗尽, 避免了沟道顶层的漏电现象导致极低的暗电 流 [63] . 2017年, 施毅和王欣然等 [64] 选用异质结作为吸光层, 构 建 了 活 性 层 结 构 为 G P P ( 石 墨 烯 / 苝 四 甲 酸 二 酐 (PTCDA)/并五苯)的光电晶体管器件(图22(a)).…”

“…Layer-defining strategy. (a-e) Photographs showing the increased spreading area of solution when the volume fraction of glycerol was increased from 10% to 100%; (f-j) corresponding OM images of the 2DMCs; (k) the spreading area of the solution and (l) the average layer number of the 2DMCs as a function of the volume fraction of glycerol[42] (color online).…”

Recent developments on organic single crystal-based light-emitting devices

“…(g) 生长出来的C6-DPA单晶照片. (h) 控制甘油溶液的体积比, 获得的不同层数的单晶材料 [45] , Copyright © 2019 Wiley-VCH Figure 5 (Color online) Growth methods for controlling crystal thickness. (a-d) Using the elastic SU-8 template, by applying pressure, an organic single-crystal array with a controllable thickness is grown.…”