Premium
Quantum Well Energetics of an n = 2 Ruddlesden–Popper Phase Perovskite
Author(s) -
Silver Scott,
Dai Qingqing,
Li Hong,
Brédas JeanLuc,
Kahn Antoine
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201901005
Subject(s) - perovskite (structure) , materials science , binding energy , surface photovoltage , density functional theory , heterojunction , phase diagram , kelvin probe force microscope , exciton , iodide , ionization energy , condensed matter physics , atomic physics , phase (matter) , crystallography , nanotechnology , ionization , computational chemistry , spectroscopy , chemistry , physics , ion , inorganic chemistry , optoelectronics , organic chemistry , quantum mechanics , atomic force microscopy
A comprehensive investigation of the electronic energy levels of an n = 2 Ruddlesden–Popper phase perovskite is presented. Ultraviolet and inverse photoemission spectroscopies are used to probe the density of states in the valence and conduction bands, respectively, of the quasi‐2D perovskite, butylammonium cesium lead iodide (BA 2 CsPb 2 I 7 ). By comparing experimental spectra with calculated projected density of states, the contributions from Cs, Pb, and I to the quantum well states are identified, and distinguished from those of the organic ligand barrier layer. The ionization energy, electron affinity, and exciton binding energy of this material are derived. The energetics of the quantum well structure are discussed in terms of the number of Pb‐halide layers. The resulting energy diagram suggests that a type‐I heterojunction would be formed with the n = 1 BA 2 PbI 4 . Finally, surface photovoltage performed via Kelvin probe force microscopy is used to evaluate band bending at the surface of the BA 2 CsPb 2 I 7 thin films.