控制晶粒长大对于最大限度地提高多晶薄膜电子器件的载流子输运具有重要意义。卤化物钙钛矿材料的薄膜生长已通过多种方法进行控制，包括溶剂工程、成分工程和后处理工艺。然而，这些方法都无法制备出具有超大晶粒尺寸和高载流子迁移率的大规模原子平坦薄膜。
该文中，研究人员开发了一种新颖的π-共轭配体设计方法，用于控制二维卤化物钙钛矿中的薄膜成核和生长动力学。通过扩展π共轭和增加半导体配体的平面度，成核密度可以降低5个数量级以上。因此，容易获得具有高度有序的晶体结构和超大晶粒尺寸的晶圆级2D钙钛矿薄膜。研究人员展示了高性能场效应晶体管，其空穴迁移率接近10 cm2 V–1 s–1，开/关电流比约为106，具有良好的稳定性和再现性。研究人员进一步建模分析证实了增强电荷传输的起源以及观察到的迁移率的场和温度依赖性，使人们能够清楚地解释这些新生的2D半导体系统中的结构-性能关系。
附：英文原文
Title: Ligand-Driven Grain Engineering of High Mobility Two-Dimensional Perovskite Thin-Film Transistors
Author: Aihui Liang, Yao Gao, Reza Asadpour, Zitang Wei, Blake P. Finkenauer, Linrui Jin, Jiaqi Yang, Kang Wang, Ke Chen, Peilin Liao, Chenhui Zhu, Libai Huang, Bryan W. Boudouris, Muhammad Ashraf Alam, Letian Dou
Issue&Volume: September 13, 2021
Abstract: Controlling grain growth is of great importance in maximizing the charge carrier transport for polycrystalline thin-film electronic devices. The thin-film growth of halide perovskite materials has been manipulated via a number of approaches including solvent engineering, composition engineering, and post-treatment processes. However, none of these methods lead to large-scale atomically flat thin films with extremely large grain size and high charge carrier mobility. Here, we demonstrate a novel π-conjugated ligand design approach for controlling the thin-film nucleation and growth kinetics in two-dimensional (2D) halide perovskites. By extending the π-conjugation and increasing the planarity of the semiconducting ligand, nucleation density can be decreased by more than 5 orders of magnitude. As a result, wafer-scale 2D perovskite thin films with highly ordered crystalline structures and extremely large grain size are readily obtained. We demonstrate high-performance field-effect transistors with hole mobility approaching 10 cm2 V–1 s–1 with ON/OFF current ratios of ～106 and excellent stability and reproducibility. Our modeling analysis further confirms the origin of enhanced charge transport and field and temperature dependence of the observed mobility, which allows for clear deciphering of the structure–property relationships in these nascent 2D semiconductor systems.
DOI: 10.1021/jacs.1c06337
Source: https://pubs.acs.org/doi/10.1021/jacs.1c06337
