Spacer-Dependent and Pressure-Tuned Structures and Optoelectronic Properties of 2D Hybrid Halide Perovskites

Abstract

Compared with their 3D counterparts, 2D hybrid organic–inorganic halide perovskites (HOIPs) exhibit enhanced chemical stabilities and superior optoelectronic properties, which can be further tuned by the application of external pressure. Here, we report the first high-pressure study on CMA2PbI4 (CMA = cylcohexanemethylammonium), a 2D HOIP with a soft organic spacer cation containing a flexible cyclohexyl ring, using UV–visible absorption, photoluminescence (PL) and vibrational spectroscopy, and synchrotron X-ray microdiffraction, all aided with density functional theory (DFT) calculations. Substantial anisotropic compression behavior is observed, as characterized by unprecedented negative linear compressibility along the b axis. Moreover, the pressure dependence of optoelectronic properties is found to be in strong contrast with those of 2D HOIPs with rigid spacer cations. DFT calculations help to understand the compression mechanisms that lead to pressure-induced bandgap narrowing. These findings highlight the important role of soft spacer cations in the pressure-tuned optoelectronic properties and provide guidance to the design of new 2D HOIPs.

Correlating Photophysical Properties with Stereochemical Expression of 6s2 Lone Pairs in Two‐dimensional Lead Halide Perovskites

“…Therefore, our study is focused on the initial compression stage. The increase of PL intensity along with decreasing AF and average PbÀ I bond length under initial compression has also been observed in another 2D LHP (CMA) 2 PbI 4 (CMA = cyclohexylmethylammonium) [49] (Figure S6). Pressure-dependent Raman spectra of (R-…”

“…The authors have cited additional references within the Supporting Information [10, 16, 54–63, 27, 64–73, 28, 74–79, 39, 49–53] …”

Correlating Photophysical Properties with Stereochemical Expression of 6s2 Lone Pairs in Two‐dimensional Lead Halide Perovskites

“…The authors have cited additional references within the Supporting Information [10, 16, 54–63, 27, 64–73, 28, 74–79, 39, 49–53] …”

Photophysical Properties of S = 5/2 Zigzag-1D (2-Bromoethylammonium)3MnBr5 Antiferromagnet

“…14,15 In addition, self-trapped exciton emission, which is a recent sensation, was observed in a few low-dimensional manganese halides. 16,17 Importantly, manganese compounds have a d 5 electronic configuration (S = 5/2 systems) and can exhibit different exotic magnetic phenomena and are rarely investigated. In fact, low-dimensional compounds with high S values can induce LRMO.…”

“…Exploring the magnetic properties is of interest since BEAMBr is composed of Mn 2+ ion having d 5 unpaired electrons (S = 5/2) with 1D structure. Figure 2a depicts its zero-field-cooled (ZFC) and field-cooled (FC) temperaturedependent magnetization measured under an applied magnetic field of H = 100 Oe.…”