Search

Chemical vapor deposition (CVD) offers a large-area, scalable, and conformal growth of perovskite thin films without the use of solvents. Low-dimensional organic–inorganic halide perovskites, with alternating layers of organic spacer groups and inorganic perovskite layers, are promising for enhancing the stability of optoelectronic devices. Moreover, their multiple quantum-well structures provide a powerful platform for tuning excitonic physics. In this work, we show that the CVD process is conducive to the growth of 2D hybrid halide perovskite films. Using butylammonium (BA) and phenylethylammonium (PEA) cations, the growth parameters of BA2PbI4and PEA2PbI4and mixed halide perovskite films were first optimized. These films are characterized by well-defined grain boundaries and display characteristic absorption and emission features of the 2D quantum wells. X-ray diffraction (XRD) and a noninteger dimensionality model of the absorption spectrum provide insights into the orientation of the crystalline planes. Unlike BA2PbI4, temperature-dependent photoluminescence measurements from PEA2PbI4show a single excitonic peak throughout the temperature range from 20 to 350 K, highlighting the lack of defect states. These results further corroborate the temperature-dependent synchrotron-based XRD results. Furthermore, the nonlinear optical properties of the CVD-grown perovskite films are investigated, and a high third harmonic generation efficiency is observed.

Abstract: Chemical vapor deposition (CVD), a low-cost and a scalable deposition technique, allows the growth of methylammonium lead iodide (MAPbI3) films without the use of solvents, substantially increasing air stability while also inducing the stable cubic phase at room temperature and at pressures as low as 0.25 GPa. MAPbI3thin films were grown by a facile two-step low-pressure vapor deposition process in a single reactor. This method results in films, which are usually in the tetragonal phase (space group: I4/mcm) and occasionally in the cubic phase under ambient conditions. High-pressure synchrotron-based X-ray diffraction studies from CVD-grown MAPbI3crystallites show that the sample remains in the cubic phase (space group: Im\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{3}$$\end{document}) between 0.25 and 3.0 GPa. Temperature-dependent transport measurements show sharp anomalies, correlating with the structural changes. The transport measurements from the CVD-grown cubic MAPI3film is further compared with a film in the tetragonal phase. Graphic Abstract: