Open AccessValence and Conduction Band Densities of States of Metal Halide Perovskites: A Combined Experimental–Theoretical Study
Author(s) -
James Endres,
David A. Egger,
Michael Kulbak,
Ross A. Kerner,
Lianfeng Zhao,
Scott Silver,
Gary Hodes,
Barry P. Rand,
David Cahen,
Leeor Kronik,
Antoine Kahn
Publication year - 2016
Publication title -
the journal of physical chemistry letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.563
H-Index - 203
ISSN - 1948-7185
DOI - 10.1021/acs.jpclett.6b00946
Subject(s) - density functional theory , valence (chemistry) , halide , chemistry , semimetal , density of states , quasi fermi level , electronic band structure , ionization energy , band gap , electron , electronic structure , condensed matter physics , molecular physics , ionization , inorganic chemistry , computational chemistry , physics , ion , organic chemistry , quantum mechanics
We report valence and conduction band densities of states measured via ultraviolet and inverse photoemission spectroscopies on three metal halide perovskites, specifically methylammonium lead iodide and bromide and cesium lead bromide (MAPbI3, MAPbBr3, CsPbBr3), grown at two different institutions on different substrates. These are compared with theoretical densities of states (DOS) calculated via density functional theory. The qualitative agreement achieved between experiment and theory leads to the identification of valence and conduction band spectral features, and allows a precise determination of the position of the band edges, ionization energy and electron affinity of the materials. The comparison reveals an unusually low DOS at the valence band maximum (VBM) of these compounds, which confirms and generalizes previous predictions of strong band dispersion and low DOS at the MAPbI3 VBM. This low DOS calls for special attention when using electron spectroscopy to determine the frontier electronic states of lead halide perovskites.