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Experimental and theoretical optical properties of methylammonium lead halide perovskites

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Aurélien M. A. Leguy ; Pooya Azarhoosh ; M. Isabel Alonso ; Mariano Campoy-Quiles ; Oliver J. Weber ; Jizhong Yao ; Daniel Bryant ; Mark T. Weller ; Jenny Nelson ; Aron Walsh ; Mark van Schilfgaarde ; Piers R. F. Barnes

Original languageEnglish
Pages (from-to)6317-6327
Number of pages11
JournalNanoscale
Volume8
Issue number12
Early online date5 Oct 2015
DOIs
StatePublished - 28 Mar 2016

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Abstract

The optical constants of methylammonium lead halide single crystals CH3NH3PbX3 (X = I, Br, Cl) are interpreted with high level ab initio calculations using the relativistic quasiparticle self-consistent GW approximation (QSGW). Good agreement between the optical constants derived from QSGW and those obtained from spectroscopic ellipsometry enables the assignment of the spectral features to their respective inter-band transitions. We show that the transition from the highest valence band (VB) to the lowest conduction band (CB) is responsible for almost all the optical response of MAPbI3 between 1.2 and 5.5 eV (with minor contributions from the second highest VB and the second lowest CB). The calculations indicate that the orientation of [CH3NH3]+ cations has a significant influence on the position of the bandgap suggesting that collective orientation of the organic moieties could result in significant local variations of the optical properties. The optical constants and energy band diagram of CH3NH3PbI3 are then used to simulate the contributions from different optical transitions to a typical transient absorption spectrum (TAS).

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