TY - JOUR

T1 - Quasi-epitaxial Metal-Halide Perovskite Ligand Shells on PbS Nanocrystals

AU - Sytnykt, Mykhailo

AU - Yakunin, Sergii

AU - Schoefberger, Wolfgang

AU - Lechner, Rainer

AU - Burian, Max

AU - Ludescher, Lukas

AU - Killilea, Niall A.

AU - YousefiAmin, AmirAbbas

AU - Kriegner, Dominik

AU - Stangl, Julian

AU - Groiss, Heiko

AU - Heiss, Wolfgang

PY - 2017/2

Y1 - 2017/2

N2 - 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 × 1011 cm Hz 1/2/W with > 110 kHz bandwidth) was obtained with (CH3NH3)3BiI6 ligands, 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 × 1013 cm–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.

AB - 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 × 1011 cm Hz 1/2/W with > 110 kHz bandwidth) was obtained with (CH3NH3)3BiI6 ligands, 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 × 1013 cm–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.

KW - nanocrystals

KW - perovskite

KW - conductive ligands

KW - epitaxy

KW - photodetectors

KW - optoelectronics

KW - semiconductors

U2 - 10.1021/acsnano.6b04721

DO - 10.1021/acsnano.6b04721

M3 - Article

VL - 11.2017

SP - 1246

EP - 1256

JO - ACS nano

JF - ACS nano

SN - 1936-0851

IS - 2

ER -