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Photoinduced quasi-2D to 3D phase transformation in hybrid halide perovskite nanoplatelets
Journal
Physical Chemistry Chemical Physics
ISSN
14639076
Date Issued
2021-12-28
Author(s)
Roy, Mrinmoy
Vikram,
Bhawna,
Alam, Aftab
Aslam, M.
Abstract
We present a photo-induced quasi-2D to 3D phase transition of MAPbBr3(MA = CH3NH3) perovskite nanoplatelets (NPLs). To begin with, we synthesized quasi-2D MAPbBr3NPLs (two octahedral layers thick,n= 2). A systematic increase in the thickness of the perovskite platelets is observed as a result of continuous photon irradiation leading to a 78 nm red shift in the emission spectra through different stages. Moreover, the bandgap of the compound decreases from 2.72 eV to 2.2 eV as we move from a quasi-2D to 3D phase. The excitonic Bohr radius of the MAPbBr3NPLs is found to be 1.8 nm, whereas the thickness of a single layer of PbBr64−octahedra is 5.9 Å. As the layer thickness increases (>4-6 layers), MAPbBr3NPLs move out of the quantum confinement regime, governed by the red shift in the emission spectra. To complement the experimental results, density functional theory calculations were performed on MAPbBr3of various layer thicknesses. The van der Waals interaction and a more accurate Heyd-Scuseria-Ernzerhof functional were used to calculate the optical bandgap for MAPbBr3platelets of different layer thicknesses, which matches exceptionally well with the experimental results. Our findings disclose an interesting and meaningful phenomenon in the emerging hybrid perovskite NPLs and are beneficial for any future development of perovskite-based devices.
Volume
23