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 (CHNH)[MHal] (M = 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 × 10 cm Hz /W with> 110 kHz bandwidth) was obtained with (CHNH)BiI 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 cm/(V s), a carrier lifetime of ∼70 μs, and a low residual carrier concentration of 2.6 × 10 cm. 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.

Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells

“…[23] Similarly, by reducing the perovskite matrix to a thickness of monolayer on the PbS CQD, an approximate model of BiI 6 3− epitaxial ligand shell on PbS CQD was demonstrated by Sytnyk et al [26] Based on the support from these reports, we constructed a coherent interfacial model between PbS and CsPbI 3 -P as shown in Figure 2f that may explain the growth of CsPbI 3 -P on the PbS CQD. [23] Similarly, by reducing the perovskite matrix to a thickness of monolayer on the PbS CQD, an approximate model of BiI 6 3− epitaxial ligand shell on PbS CQD was demonstrated by Sytnyk et al [26] Based on the support from these reports, we constructed a coherent interfacial model between PbS and CsPbI 3 -P as shown in Figure 2f that may explain the growth of CsPbI 3 -P on the PbS CQD.…”

“…[23] Similarly, by reducing the perovskite matrix to a thickness of monolayer on the PbS CQD, an approximate model of BiI 6 3− epitaxial ligand shell on PbS CQD was demonstrated by Sytnyk et al [26] Based on the support from these reports, we constructed a coherent interfacial model between PbS and CsPbI 3 -P as shown in Figure 2f that may explain the growth of CsPbI 3 -P on the PbS CQD. As demonstrated by Sytnyk et al, [26] to form the perovskite ligand shell on PbS CQD surface, the perovskite octahedral ligand have to coalesce on the CQD surface so that the adhering neighboring octahedral share edge and corner ions ( Figure 2f). As demonstrated by Sytnyk et al, [26] to form the perovskite ligand shell on PbS CQD surface, the perovskite octahedral ligand have to coalesce on the CQD surface so that the adhering neighboring octahedral share edge and corner ions ( Figure 2f).…”

“…[22][23][24][25][26][27][28] Solution-processed growth perovskite on the PbS CQD that may be triggered by epitaxial conditions could enable nearly defect free heterostructures with coherent interfaces, which is critical for the development of high performance photovoltaics and other optoelectronic devices. [22][23][24][25][26][27][28] Solution-processed growth perovskite on the PbS CQD that may be triggered by epitaxial conditions could enable nearly defect free heterostructures with coherent interfaces, which is critical for the development of high performance photovoltaics and other optoelectronic devices.…”

Recent Advances in Halide Perovskite Photodetectors Based on Different Dimensional Materials

“…Nearly defect‐free heterostructures with coherent interfaces are of the utmost importance for high‐performance electronic devices. Different octahedral metal‐halide clusters ((CH 3 NH 3 + ) (6− x ) [M ( x +) Hal 6 ] (6− x )− , M x + = Pb(II), Bi(III), Mn(II), In(III), Hal = Cl, I) and 0D perovskites were also employed as ligands to match the lattice of PbS QDs via a solution‐processing approach by Sytnyk et al The photoconducting devices with MA 3 BiI 6 ligands showed a high detectivity of 2 × 10 11 cm Hz 1/2 W −1 with an over 110 kHz bandwidth due to the small relative lattice mismatch of ≈−1%. The results showed that quasiepitaxial ligand shells were formed on NCs by the selection of ligands with appropriate geometry and optimized bond lengths, which are beneficial for applications in optoelectronics.…”

“…In addition to the highly successful application of perovskite materials in solar cells with photo‐to‐electric conversion efficiency increasing from 3.8% to 22.1% within past few years, advancements in halide perovskite photodetectors (HPPDs) incorporated with different dimensional materials have also been achieved, such as 0D (quantum dots (QDs): PbS, ZnS, PbSe, etc. ), 1D (nanowires or nanowire arrays: ZnO, TiO 2 , carbon nanotubes (CNTs), etc.…”