Seed-Mediated Synthesis of Photoluminescent Cu–Zn–In–S Nanoplatelets

Abstract

Ternary and quaternary colloidal nanocrystals (NCs) based on I–III–VI group semiconductors are promising low-toxic luminescent materials attracting huge interest as alternatives to cadmium- and lead-chalcogenide-based NCs. Despite significant progress in the synthesis of three-dimensionally confined quantum dots based on I–III–VI semiconductors with intensive photoluminescence (PL) in a broad spectral range, all attempts to prepare one-dimensionally confined nanoplatelets (NPLs) or nanosheets have resulted in rather nonemitting two-dimensional (2D) NCs. Since 2D NCs of the II–VI group exhibit unique anisotropic optical properties, exploring synthetic strategies to obtain 2D I–III–VI-based NPLs might also reveal interesting optical and electronic features. In this work, we demonstrate the synthesis of luminescent In-rich Cu–Zn–In–S (CZIS) NPLs using a one-pot approach. The synthesis includes the formation of Cu–In–S NPLs from In2S3 seeds, followed by the incorporation of zinc to form quaternary NPLs with improved stability and optical properties. The synthetic strategy implemented results in the formation of ∼1 nm thick NPLs with lateral sizes of ∼30 × 10 nm2 and a tetragonal crystal structure. As-synthesized NPLs are stable at ambient conditions and demonstrate PL in the range of 700–800 nm with a large Stokes shift. An additional shell of ZnS grown on CZIS NPLs resulted in the enhancement of their PL quantum yield reaching 29%.

Mn2+-Doped ZnSe/ZnS Core/Shell Nanoplatelets as Low-Toxic UV-to-Vis Light-Converters with Enhanced Optical Properties

“…To exclude the contribution of ligands to the shell thickness, TEM measurements on stacked NPLs were performed. From TEM images (Figure S7), very narrow stripes with dark contrast can be observed, which is regarded as stacking of NPLs. , The length of the stripes is found to be close to the average length of the NPLs, suggesting that the stripes are indeed NPLs standing vertically on the TEM grid. The average thickness of the core/shell NPLs is 2.95 ± 0.10 nm, thicker than that of the core NPLs (1.28 ± 0.07 nm).…”

Composition-Dependent Optical Properties of Cu–Zn–In–Se Colloidal Nanocrystals Synthesized via Cation Exchange

“…This suggests that, despite a narrow size distribution, the reason for broad PL can still be attributed to the ensemble heterogeneity in terms of its composition variation from particle to particle. Such variations in composition are most likely responsible for broad PL spectra, recently found also in thin CZIS nanoplatelets with uniform thickness and quite strong quantum confinement within the thickness dimension . This sample heterogeneity results in a large number of Cu-related emission centers, which are positioned randomly.…”

“…Such variations in composition are most likely responsible for broad PL spectra, recently found also in thin CZIS nanoplatelets with uniform thickness and quite strong quantum confinement within the thickness dimension. 52 This sample heterogeneity results in a large number of Cu-related emission centers, which are positioned randomly. Such random positioning results in varying energy contributions from the electron−hole coupling to the total PL energy, exhibiting a broad PL spectrum.…”

Cation exchange synthesis of AgBiS2 quantum dots for highly efficient solar cells

“…[35][36][37] The outcome of a CE reaction is dictated by subtle thermodynamic and kinetic factors enabling the control over the structure and composition of the desired product. 33 The choice of size, shape, and structure of the parent nanocrystals as well as the choice of solvent, additional ligands, and temperature of the reaction allows not only to tune the morphology and composition of the final products, 38,39 but also to prepare various heterostructures such as Cu-In-Se/ZnS core-shell nanoparticles or CdS/Cu 2 S binary nanorods. 40,41 Despite the widespread use of CE for synthesizing ternary nanoparticles, the synthesis of AgBiS 2 QDs using this approach has not yet been reported.…”