In Situ Synthesis of PbS Nanocrystals in Polymer Thin Films from Lead(II) Xanthate and Dithiocarbamate Complexes: Evidence for Size and Morphology Control

Abstract

Lead sulfide has been grown from single molecular precursors within a polymer matrix to form networks of PbS nanocrystals. These materials are model systems for the processing of polymer-nanoparticle layers for flexible hybrid photovoltaic devices. Processing is achieved by spin coating a solution containing the precursor and polymer on to a substrate, followed by heating of the film to decompose the precursor. The effect of precursor chemistry has been explored using: lead(II) dithiocarbamates, their 1,10-phen adducts, and lead(II) xanthates with different alkyl chain lengths (butyl, hexyl, and octyl). The xanthates were found to be more promising precursors giving control over nanocrystal size and shape on variation of the alkyl chain length. The lead(II) octyl xanthate complex causes anisotropic growth, forming PbS nanowires within the polymer matrix.

Nickel sulfide thin films and nanocrystals synthesized from nickel xanthate precursors

“…The observed changes in film morphology may be derived from several factors such as the different primary crystallite sizes (28 nm for NiXa-C6, 22 nm for NiXa-C7), differences in crystallization behavior of the precursors during deposition of the precursor films or different precursor reactivities, which have important implications on nucleation and growth kinetics. Regarding this latter issue, MacLachlan et al [53] and Lewis et al [60] have already demonstrated that the morphology of metal sulfide nanocomposites can be efficiently tuned by the chemical structure of xanthate or dithiocarbamate complexes. Similar as in the work of Lewis et al, the observed differences in film morphology in this study might also originate from changes in precursor reactivity.…”

“…The attractive properties of metal xanthates, like their usually good stability (also in solution), relatively low decomposition temperature (below 200°C) and simplicity to tailor solubility and decomposition behavior by variation of their organic side chains, have ensured that they are widely employed in the preparation of various metal sulfide nanomaterials [35][36][37][38][39][51][52][53][54][55][56][57][58][59][60].…”

“…A variety of binary (Bi 2 S 3 [52,61], CdS [53], CuS [36], HgS [36], MnS [36], ZnS [36], PbS [60], PdS [35], SnS [59], NiS [35][36][37][38][39]), ternary (copper indium sulfide [51], copper antimony sulfide [54]) and quaternary (copper zinc tin sulfide [55]) metal sulfide nanomaterials have already been synthesized via a thermally induced decomposition of the metal xanthates, proceeding via the Chugaev elimination mechanism [36,51]. Far less explored is the conversion of metal xanthates to metal sulfides at room temperature by photochemically induced decomposition using UV irradiation [56,57] or direct chemical reaction with primary amines.…”

A facile method for the production of SnS thin films from melt reactions

“…The use of the xanthate ligand in SSPs has permitted the formation of many metal sulfides, including, but not limited to, MoS 2 [20], CdS [21], NiS, PdS [22], and CZTS [23], at lower temperatures than those needed by their respective (N,N-dialklydithiocarbamato-) analogs. Recently, we have reported the preparations of PbS/polymer composites from both lead(II)xanthate and lead(II)dithiocarbamate complexes by a melt process [18,24], finding that the decomposition of Pb(S 2 CO n Bu) 2 in a polymer matrix produced pure cubic PbS nanocrystals at 150°C; significantly lower temperatures than 275°C are needed to decompose Pb(S 2 CN n Bu 2 ) 2 . As a result, the xanthate-containing SSP can be used in a wider temperature window, giving greater control over nanocrystal size, shape variation, and orientation preference of the PbS crystals.…”

The synthesis and characterization of Cu2ZnSnS4 thin films from melt reactions using xanthate precursors

“…Recently xanthates have been used as SSPs to metal sulfide nanocrystals [44][45][46][47][48][49]. They have the general chemical formula [M(S 2 COR) n ], where R is an alkyl group.…”