title: Enhanced Organo-Metal Halide Perovskite Photoluminescence from Nanosized Defect-Free Crystallites and Emitting Sites.
abstract: Photoluminescence (PL) of organo-metal halide perovskite semiconductors can be enhanced by several orders of magnitude by exposure to visible light. We applied PL microscopy and super-resolution optical imaging to investigate this phenomenon with spatial resolution better than 10 nm using films of CH3NH3PbI3 prepared by the equimolar solution-deposition method, resulting in crystals of different sizes. We found that PL of ∼100 nm crystals enhances much faster than that of larger, micrometer-sized ones. This crystal-size dependence of the photochemical light passivation of charge traps responsible for PL quenching allowed us to conclude that traps are present in the entire crystal volume rather than at the surface only. Because of this effect, "dark" micrometer-sized perovskite crystals can be converted into highly luminescent smaller ones just by mechanical grinding. Super-resolution optical imaging shows spatial inhomogeneity of the PL intensity within perovskite crystals and the existence of <100 nm-sized localized emitting sites. The possible origin of these sites is discussed.
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Aboma
authors.initials: A
authors.lastname: Merdasa
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Unger
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Abdellah
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Kaibo
authors.initials: K
authors.lastname: Zheng
authors.affiliation: Division of Synchrotron Radiation Research, Lund University , Box 118, 221 00 Lund, Sweden.
authors.forename: Sarah
authors.initials: S
authors.lastname: McKibbin
authors.affiliation: Division of Synchrotron Radiation Research, Lund University , Box 118, 221 00 Lund, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Mikkelsen
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Pullerits
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Arkady
authors.initials: A
authors.lastname: Yartsev
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström
authors.affiliation: Chemical Physics, Lund University , Box 124, SE-22100 Lund, Sweden.
authors.forename: Ivan G
authors.initials: IG
authors.lastname: Scheblykin