Ultrathin Orthorhombic PbS Nanosheets

Abstract

Colloidal lead sulfide nanosheets have attracted broad interest for a wide variety of device applications, including field-effect transistors, solar cells, and spintronic devices. Whereas confinement effects in PbS quantum dots are well studied, they are still unclear in 2-dimensional ultrathin PbS nanosheets, especially in the 1 nm thickness range. In this work, we report a synthesis of monodisperse, rectangular-shaped PbS nanosheets with a thickness of 1.2 nm, using Pb­(thiocyanate)2 as a single source precursor. These nanosheets have an orthorhombic crystal structure, a direct bandgap, and weak optical absorption properties. This is evident from the lack of both excitonic absorption features and photoluminescence, and was corroborated by density functional theory calculations. Although these properties make the PbS nanosheets unsuitable for emission based applications, the nanosheets are highly photoconductive in films, with a responsivity up to 0.1 A W–1 and a detectivity of 1.3 × 109 Jones. We detected higher photoconductivity of these films under bending stress compared to that of films of PbS quantum dots.

Nanocrystals of Lead Chalcohalides: A Series of Kinetically Trapped Metastable Nanostructures

“…In the FTIR spectrum of the as-prepared NCs ( Figure S35, top spectrum) one can observe main bands located at 2953/2924/2853 cm -1 together with features at 1466/1412 cm -1 which corresponds respectively to the CH3 and CH2 stretching and CH2 bending of the alkyl chains from oleic acid and/or oleylamine. 26,64 Moreover, the appearance of a band at 1520 cm -1 corresponding to the C=O stretching confirms the presence of Pb-bound oleate at the NC surface. 64 A broad band at 2040 cm -1 (S=C=N stretching) and features at 1312/1266 cm -1 (C-N stretching), which can be attributed to SCNand to oleylamine attached at the NC surface respectively, were present as well.…”

“…All the syntheses of Pb 4 S 3 Br 2 NCs were performed in air, without predrying chemicals or solvents, via a heat-up synthetic approach similar to the one developed by us for the synthesis of ultrathin PbS nanosheets. 26 Briefly, 0.2 mmol of PbBr 2 and 0.2 mmol of Pb(SCN) 2 were dissolved in a mixture of 10 mL of ODE and 250 μL of OLAM and OA at 120 °C in a 25 mL three-necked flask. Then, the solution was quickly heated (∼20 °C/min) and started turning from light yellow to blood red above 150 °C, while the NCs nucleated and grew.…”

2D Materials Based on Main Group Element Compounds: Phases, Synthesis, Characterization, and Applications

“…This may result in the preparation of 2D metal chalcogenides using other metal thiocyanate precursors. [216] With respect to 2D PbSe, only the rock-salt phase was reported. [217] Similar to PbS, a solution-based method was used to prepare 2D PbSe with a controllable thickness from 2 to 6 nm.…”

Controlling the Lateral Size and Excitonic Properties of Colloidal PbS Nanosheets

“…Colloidal PbS nanosheets are a new type of infrared nanostructure that can be synthesized using a wet‐chemistry method . Since the first synthesis of colloidal PbS nanosheets by Weller's group, the systematic thickness tuning has been achieved by Sun's group through changing the reaction temperature .…”