title: Electronic Structure and Optical Properties of α-CH3NH3PbBr3 Perovskite Single Crystal.
abstract: The electronic structure and related optical properties of an emerging thin-film photovoltaic material CH3NH3PbBr3 are studied. A block-shaped α-phase CH3NH3PbBr3 single crystal with the natural ⟨100⟩ surface is synthesized solvothermally. The room-temperature dielectric function ε = ε1 + iε2 spectrum of CH3NH3PbBr3 is determined by spectroscopic ellipsometry from 0.73 to 6.45 eV. Data are modeled with a series of Tauc-Lorentz oscillators, which show the absorption edge with a strong excitonic transition at ∼2.3 eV and several above-bandgap optical structures associated with the electronic interband transitions. The energy band structure and ε data of CH3NH3PbBr3 for the CH3NH3(+) molecules oriented in the ⟨111⟩ and ⟨100⟩ directions are obtained from first-principles calculations. The overall shape of ε data shows a qualitatively good agreement with experimental results. Electronic origins of major optical structures are discussed.
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Ji-Sang
authors.initials: JS
authors.lastname: Park
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Sukgeun
authors.initials: S
authors.lastname: Choi
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yan
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Ye
authors.initials: Y
authors.lastname: Yang
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Luther
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Philip
authors.initials: P
authors.lastname: Parilla
authors.affiliation: National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhu
keywords: density functional theory calculations; electronic structure; optical property; perovskite solar cell; spectroscopic ellipsometry