Issue 12, 2020

Bandgap determination from individual orthorhombic thin cesium lead bromide nanosheets by electron energy-loss spectroscopy

Abstract

Inorganic lead halide perovskites are promising candidates for optoelectronic applications, due to their high photoluminescence quantum yield and narrow emission line widths. Particularly attractive is the possibility to vary the bandgap as a function of the halide composition and the size or shape of the crystals at the nanoscale. Here we present an aberration-corrected scanning transmission electron microscopy (STEM) and monochromated electron energy-loss spectroscopy (EELS) study of extended nanosheets of CsPbBr3. We demonstrate their orthorhombic crystal structure and their lateral termination with Cs–Br planes. The bandgaps are measured from individual nanosheets, avoiding the effect of the size distribution which is present in standard optical spectroscopy techniques. We find an increase of the bandgap starting at thicknesses below 10 nm, confirming the less marked effect of 1D confinement in nanosheets compared to the 3D confinement observed in quantum dots, as predicted by density functional theory calculations and optical spectroscopy data from ensemble measurements.

Graphical abstract: Bandgap determination from individual orthorhombic thin cesium lead bromide nanosheets by electron energy-loss spectroscopy

Supplementary files

Article information

Article type
Communication
Submitted
04 Aug 2020
Accepted
20 Oct 2020
First published
20 Oct 2020
This article is Open Access
Creative Commons BY license

Nanoscale Horiz., 2020,5, 1610-1617

Bandgap determination from individual orthorhombic thin cesium lead bromide nanosheets by electron energy-loss spectroscopy

R. Brescia, S. Toso, Q. Ramasse, L. Manna, J. Shamsi, C. Downing, A. Calzolari and G. Bertoni, Nanoscale Horiz., 2020, 5, 1610 DOI: 10.1039/D0NH00477D

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