title: Quasi-epitaxial Metal-Halide Perovskite Ligand Shells on PbS Nanocrystals.
abstract: Epitaxial growth techniques enable nearly defect free heterostructures with coherent interfaces, which are of utmost importance for high performance electronic devices. While high-vacuum technology-based growth techniques are state-of-the art, here we pursue a purely solution processed approach to obtain nanocrystals with eptaxially coherent and quasi-lattice matched inorganic ligand shells. Octahedral metal-halide clusters, respectively 0-dimensional perovskites, were employed as ligands to match the coordination geometry of the PbS cubic rock-salt lattice. Different clusters (CH3NH3+)(6-x)[M(x+)Hal6](6-x)-(Mx+= Pb(II), Bi(III), Mn(II), In(III), Hal = Cl, I) were attached to the nanocrystal surfaces via a scalable phase transfer procedure. The ligand attachment and coherence of the formed PbS/ligand core/shell interface was confirmed by combining the results from transmission electron microscopy, small-angle X-ray scattering, nuclear magnetic resonance spectroscopy and powder X-ray diffraction. The lattice mismatch between ligand shell and nanocrystal core plays a key role in performance. In photoconducting devices the best performance (detectivity of 2 × 1011cm Hz1/2/W with > 110 kHz bandwidth) was obtained with (CH3NH3)3BiI6ligands, providing the smallest relative lattice mismatch of ca. -1%. PbS nanocrystals with such ligands exhibited in millimeter sized bulk samples in the form of pressed pellets a relatively high carrier mobility for nanocrystal solids of ∼1.3 cm2/(V s), a carrier lifetime of ∼70 μs, and a low residual carrier concentration of 2.6 × 1013cm-3. Thus, by selection of ligands with appropriate geometry and bond lengths optimized quasi-epitaxial ligand shells were formed on nanocrystals, which are beneficial for applications in optoelectronics.
authors.affiliation: Materials Science Department (Materials for Electronics and Energy Technology), Friedrich-Alexander Universität Erlangen-Nürnberg , Energy Campus Nürnberg, Nürnberg 90429, Germany.
authors.forename: Mykhailo
authors.initials: M
authors.lastname: Sytnyk
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , Linz 4040, Austria.
authors.forename: Sergii
authors.identifier: 0000-0002-6409-0565
authors.initials: S
authors.lastname: Yakunin
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz , Linz 4040, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schöfberger
authors.affiliation: Institute of Physics, Montanuniversitaet Leoben , Leoben 8700, Austria.
authors.forename: Rainer T
authors.initials: RT
authors.lastname: Lechner
authors.affiliation: Institute of Physics, Montanuniversitaet Leoben , Leoben 8700, Austria.
authors.forename: Max
authors.initials: M
authors.lastname: Burian
authors.affiliation: Institute of Physics, Montanuniversitaet Leoben , Leoben 8700, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Ludescher
authors.affiliation: Materials Science Department (Materials for Electronics and Energy Technology), Friedrich-Alexander Universität Erlangen-Nürnberg , Energy Campus Nürnberg, Nürnberg 90429, Germany.
authors.forename: Niall A
authors.initials: NA
authors.lastname: Killilea
authors.affiliation: Materials Science Department (Materials for Electronics and Energy Technology), Friedrich-Alexander Universität Erlangen-Nürnberg , Energy Campus Nürnberg, Nürnberg 90429, Germany.
authors.forename: AmirAbbas
authors.initials: A
authors.lastname: YousefiAmin
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , Linz 4040, Austria.|Department of Condensed Matter Physics, Charles University Prague , Prague 12116, Czech Republic.
authors.forename: Dominik
authors.identifier: 0000-0001-6961-6581
authors.initials: D
authors.lastname: Kriegner
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , Linz 4040, Austria.
authors.forename: Julian
authors.initials: J
authors.lastname: Stangl
authors.affiliation: Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz , Linz 4040, Austria.|Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT) , Karlsruhe 76128, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Groiss
authors.affiliation: Materials Science Department (Materials for Electronics and Energy Technology), Friedrich-Alexander Universität Erlangen-Nürnberg , Energy Campus Nürnberg, Nürnberg 90429, Germany.
authors.forename: Wolfgang
authors.identifier: 0000-0003-0430-9550
authors.initials: W
authors.lastname: Heiss
keywords: conductive ligands; epitaxy; nanocrystals; optoelectronics; perovskite; photodetectors; semiconductors